atypical Nor-98, CH1641, Scrapie, TSE Prion, Update 2026
atypical Nor-98 Scrapie Update 2025 Scrapie typical and atypical USA
FY 2023, 16,646 from sheep and 8,726 from goats.
* There have been 491 NVSL confirmed positive animals (474 classical cases – 471 sheep and 3 goats) and
19 Nor98- like cases since the beginning of RSSS. Figure 3 depicts RSSS collection sites in FY 2023.
https://www.aphis.usda.gov/sites/default/files/scrapie-annual-report.pdf
In 2023, APHIS collected samples from more than 26,000 sheep and goats for scrapie testing. Out of the total number of animals tested in 2023, no animals tested positive for classical scrapie and
one sheep tested positive for non-classical scrapie (Nor98-like)...
https://www.usda.gov/sites/default/files/documents/22-APHIS-2025-ExNotes.pdf
In 2022, APHIS collected samples from more than 23,000 sheep and goats for scrapie testing. Out of the total number of animals tested in 2022, no animals tested positive for classical scrapie and
one sheep tested positive for non-classical scrapie (Nor98-like).
https://www.usda.gov/sites/default/files/documents/23-2024-APHIS.pdf
In FY 2021, APHIS collected samples from more than 30,000 sheep and goats for scrapie testing. Out of the total number of samples processed and reported in FY 2021,
one sheep tested positive for classical scrapie and one sheep tested positive for non-classical scrapie (Nor98-like).
https://www.usda.gov/sites/default/files/documents/23-2023-APHIS.pdf
In FY 2020, APHIS collected samples from 33,839 sheep and goats for scrapie testing. This number represents sample results reported by October 15, 2020 and is expected to slightly increase as the remaining results are processed and reported. No animals tested positive for classical scrapie.
Two sheep tested positive at slaughter for non-classical scrapie (Nor98-like).
https://www.usda.gov/sites/default/files/documents/22APHIS2022Notes.pdf
In FY 2019, APHIS collected samples from 34,730 sheep and goats for scrapie testing, detecting 7 classical scrapie positive animals. Of these animals, five sheep and one goat were from a source flock in Pennsylvania that was found in August 2018, depopulated in October 2018, and tested for scrapie in November 2018. A second goat, which was from an Indiana herd, was sampled at slaughter in June 2019. The source flock completed a cleanup plan and was placed on a 5-year monitoring plan. The source herd of the positive Indiana goat no longer contained any exposed animals and was also placed on a 5-year monitoring plan. A trace-back investigation narrowed the goat’s birth herd to two possible herds. Animals in both herds tested negative for scrapie and were placed on 5-year monitoring plans. There were no classical scrapie cases detected in slaughter sheep in FY 2019.
Also in FY 2019, two sheep tested positive at slaughter for non-classical scrapie (Nor98-like) and were traced back to Colorado flocks.
https://www.usda.gov/sites/default/files/documents/20aphis2021notes.pdf
In FY 2018, APHIS collected samples from 43,625 sheep and goats for scrapie testing, detecting three positive (0.0068%) cases. These figures are based on sample submissions and testing completed by September 30, 2018. FY 2018 values are expected to change when testing is completed for all animals sampled in FY 2018.
In October 2017, a non-classical scrapie case was detected in a sheep from Virginia sampled at slaughter. As a result, the non- classical scrapie affected flock was placed on a 5-year monitoring plan.
https://www.usda.gov/sites/default/files/documents/20aphis2020notes.pdf
In FY 2016, the program identified one flock infected with classical scrapie and one infected with Nor98-like scrapie through slaughter surveillance, and two flocks infected with classical scrapie through on-farm surveillance.
An additional 10 sheep were confirmed with classical scrapie through testing of sheep depopulated from these infected flocks as part of flock clean-up activities conducted in FY 2016.
The Nor98-like scrapie affected flock will be placed on a 5-year monitoring plan.
https://www.usda.gov/sites/default/files/documents/20aphisexnotes2018.pdf
Atypical Nor-98 Scrapie TSE Prion USA State by State Update January 2021
Atypical Nor-98 Scrapie TSE Prion USA State by State Update January 2021
Nor98 cases Diagnosed in the US. To Date
Nor98 cases Diagnosed in the US.
Flock of Origin State FY
Wyoming 2007
Indiana 2007
Pennsylvania 2008
Oregon 2010
Ohio 2010
Pennsylvania 2010
Untraceable 2010
California 2011
Montana 2016
Utah 2017
Montana 2017
Virginia 2018
Colorado 2019
Colorado 2019
Wyoming 2020
Montana 2020
Pennsylvania 2021
Personal Communication from USDA et al Mon, Jan 4, 2021 11:37 am...terry
TUESDAY, SEPTEMBER 22, 2020
APHIS USDA MORE SCRAPIE ATYPICAL Nor-98 Confirmed USA September 15 2020
17 cases of the Nor98 in the USA to date, location, unknown...tss
17 Nor98-like cases since the beginning of RSSS.
https://www.aphis.usda.gov/animal_health/animal_diseases/scrapie/downloads/monthly_scrapie_report.pdf
17 Nor98-like cases since the beginning of RSSS. No animals have tested positive for classical scrapie in FY 2021.
https://www.aphis.usda.gov/animal_health/animal_diseases/scrapie/downloads/monthly_scrapie_report.pdf
TUESDAY, SEPTEMBER 22, 2020
APHIS USDA MORE SCRAPIE ATYPICAL Nor-98 Confirmed USA September 15 2020
https://scrapie-usa.blogspot.com/2020/09/aphis-usda-more-scrapie-atypical-nor-98.html
MONDAY, JULY 27, 2020
APHIS USDA Nor98-like scrapie was confirmed in a sheep sampled at slaughter in May 2020
https://nor-98.blogspot.com/2020/07/aphis-usda-nor98-like-scrapie-was.html
MONDAY, JULY 13, 2020
Efficient transmission of classical scrapie agent x124 by intralingual route to genetically susceptible sheep with a low dose inoculum
https://scrapie-usa.blogspot.com/2020/07/efficient-transmission-of-classical.html
*** Singeltary reply ; Molecular, Biochemical and Genetic Characteristics of BSE in Canada Singeltary reply ;
https://journals.plos.org/plosone/article/comment?id=10.1371/annotation/4f9be886-69fe-4c7c-922b-85b0ecbe6d53
WEDNESDAY, MAY 29, 2019
***> Incomplete inactivation of atypical scrapie following recommended autoclave decontamination procedures
https://nor-98.blogspot.com/2019/05/incomplete-inactivation-of-atypical.html
THURSDAY, DECEMBER 31, 2020
Autoclave treatment of the classical scrapie agent US No. 13-7 and experimental inoculation to susceptible VRQ/ARQ sheep via the oral route results in decreased transmission efficiency
https://scrapie-usa.blogspot.com/2020/12/autoclave-treatment-of-classical.html
Snip…see full text;
https://nor-98.blogspot.com/2021/01/atypical-nor-98-scrapie-tse-prion-usa.html
2025-2026
ARS Research Project: Elucidating the Pathobiology and Transmission of Transmissible Spongiform Encephalopathies 2025
“ARS researchers in Ames, Iowa, showed that white-tailed deer sick with scrapie from sheep can infect other deer under conditions mimicking natural exposure. Furthermore, this work shows that CWD is difficult to differentiate from WTD infected with scrapie. WTD scrapie prions accumulate in the lymphoreticular system in a manner similar to CWD, meaning that environmental contamination may occur through feces, saliva, and other body fluids of scrapie affected WTD as has been shown for CWD. The presence of WTD infected with scrapie could confound mitigation efforts for chronic wasting disease. This information informs regulatory officials, the farmed cervid industry, and officials tasked with protecting animal health such as state Departments of Agriculture, Natural Resources, or Parks and Wildlife with regard to a disease similar to CWD but arising from sheep scrapie that could be present in WTD that have contact with scrapie affected sheep and/or goats.”
Research Project: Elucidating the Pathobiology and Transmission of Transmissible Spongiform Encephalopathies
Location: Virus and Prion Research
2025 Annual Report
Objectives
Objective 1: Develop highly sensitive detection tools to determine the distribution of CWD and scrapie prions in natural hosts (sheep, goats, cervids) and their environment.
Objective 2: Investigate the pathobiology of CWD, scrapie prion strains, and atypical TSEs in natural hosts including potential cross species transmission events.
Objective 3: Investigate the genetics of CWD susceptibility and resistance in white-tailed deer.
Objective 4: Evaluate the presence of and determine the appropriate methodology for CWD strain determination.
Approach
Eradication or control of a family of diseases is unlikely or impossible when an understanding of the basic mechanisms and influences on transmission are unknown and for which methods to evaluate disease status are lacking. Scrapie and BSE represent the most thoroughly studied TSEs; however, significant knowledge gaps persist with regard to the atypical variants of these diseases. Further, much of the research emphasis to date on genetics of prion disease has focused on the recipient genotype rather than the source. Since both atypical BSE and atypical scrapie have been suggested to occur spontaneously, eradication of these diseases may not be possible unless we expand our understanding of the disease at both the source and recipient level. A better understanding of the tissue distribution and potential transmission of these atypical isolates is critical to understanding what risk these disease variants may pose to ongoing control and eradication efforts. The European epizootic of BSE is waning and efforts to eradicate scrapie in the U.S. and abroad have progressed but are not complete. In the U.S., chronic wasting disease (CWD) presents the most serious challenge to regulatory efforts. CWD appears to be spreading unchecked in both free-ranging and farmed cervids. Methods for antemortem detection of TSEs in general and CWD in particular are needed to fulfill the goal of eradicating scrapie and controlling CWD. Performing these studies will allow us to address critical knowledge gaps that are relevant to developing measures to restrict further disease expansion beyond current, affected populations. Understanding prion disease persistence in animal populations is challenging due to lack of tools for study and a less than complete understanding of transmission among animals within a flock or herd or in naturally occurring reservoirs. In addition to transmission between hosts of like species, free-ranging cervids may come in contact with numerous other species including cattle, sheep, and other susceptible hosts. Transmission of CWD to other species has been studied but limited with regard to the source genotype used. The four primary objectives are inherently linked. Our focus is on developing tools needed for control and research, and using those tools to advance our understanding the complex disease process with the overall goal of eradication and control of disease in livestock, wildlife of economic importance, and potential wildlife reservoirs.
Progress Report
The goals of the project plan for fiscal year (FY) 2025 consisted of 12 milestones, 11 of which were either fully or substantially met. The only milestone in this plan that was not met was due to insufficient animal availability and space constraints. Previous studies utilizing this space are not complete due to longer than anticipated incubation periods and cannot be initiated until those studies are complete. In work toward addressing
Objective 1, “Develop highly sensitive detection tools to determine the distribution of chronic wasting disease (CWD) and scrapie prions in natural hosts (sheep, goats, cervids) and their environment”, we have worked closely with ARS researchers in Pullman, Washington, Animal and Plant Health Inspection Service (APHIS), and university partners. The tools under development are directly utilized by state diagnostic labs and have been shared with the appropriate end users for evaluation. We have also assessed alternative dyes that have do not induce amyloid formation in the amplification based diagnostic assay known as RT-QuIC. While no increase in sensitivity was observed, differences between strains were found offering an additional means to differentiate strains for some TSEs.
Objective 2, “Investigate the pathobiology of CWD, scrapie prion strains, and atypical TSEs in natural hosts including potential cross species transmission events”, the studies in question have been initiated with the goal of furthering the understanding of these TSEs in agriculturally relevant species including the natural host species and other that may be exposed to these TSEs in an agricultural environment. The studies are ongoing and anticipated to last upwards of 5 year and observation of the animals is ongoing. No anticipated signs of disease or relevant reportable information have been seen nor are they expected until near the onset of clinical signs, but if they are observed they will be reported.
Objective 3, “Investigate the genetics of CWD susceptibility and resistance in white-tailed deer”, consists of two subobjectives:
A) Investigate the susceptibility of white-tailed deer to CWD modeling direct contact exposure with infected deer, and
B) Investigate the susceptibility of white-tailed deer to CWD after direct inoculation.
The first of these has been initiated on schedule while the second has been delayed considerably (greater than 3 years at this point) due to insufficient animal space.Upon completion these two studies will aid in understanding the disease and disease progression.
Objective 4, “Evaluate the presence of and determine the appropriate methodology for CWD strain determination”, is dependent upon obtaining a diverse set of CWD isolates. We are continuing the acquisition of these samples. . Strains are one of the least understood aspects of TSEs as a whole and of importance in understanding the risks of CWD. We have initiated studies that will address the biochemical nature of prion strains and how these strains are maintained in a host which will aid in addressing features and differentiation of strains as additional samples become available.
Accomplishments
1. 01 Determined that white-tailed deer (WTD) infected with scrapie from sheep can transmit the disease to other deer under conditions mimicking natural exposure. It has long been suggested that prion disease in deer (chronic wasting disease (CWD)) was caused by the prion agent from sheep. The prion disease that affects sheep, scrapie, has been recognized for hundreds of years. However, chronic wasting disease, a similar disease found in WTD, has only been recognized since the 1960s. ARS researchers in Ames, Iowa, showed that white-tailed deer sick with scrapie from sheep can infect other deer under conditions mimicking natural exposure. Furthermore, this work shows that CWD is difficult to differentiate from WTD infected with scrapie. WTD scrapie prions accumulate in the lymphoreticular system in a manner similar to CWD, meaning that environmental contamination may occur through feces, saliva, and other body fluids of scrapie affected WTD as has been shown for CWD. The presence of WTD infected with scrapie could confound mitigation efforts for chronic wasting disease. This information informs regulatory officials, the farmed cervid industry, and officials tasked with protecting animal health such as state Departments of Agriculture, Natural Resources, or Parks and Wildlife with regard to a disease similar to CWD but arising from sheep scrapie that could be present in WTD that have contact with scrapie affected sheep and/or goats.
2. 02 Showed that gene-targeted mice are capable of reproducing strain specific effects typically limited to natural host species of chronic wasting disease (CWD). CWD is a highly contagious disease of deer, elk, moose, and reindeer found in North America, South Korea, and Scandinavian countries that is caused by misfolded proteins called prions. CWD prions transmit through direct contact between infected animals, or through contaminated soil, grass, or water. All prion diseases exhibit progressive neurodegeneration and ultimately death. Scientists typically study CWD by injecting prions into susceptible animals' brains in lab experiments. Intracranial prion injections are favored because they typically produce shorter incubation periods and higher disease attack rates compared to natural infection. ARS researchers in Ames, Iowa, along with university collaborators showed that this inoculation method can cause the prion strains to change in a way that does not accurately reflect how the disease spreads naturally. They found that using a combination of peripheral inoculation (injection outside the brain) in natural hosts and using novel gene-targeted mice generated in a manner that provides a more natural expression of the inserted prion gene that gives a more accurate picture of how CWD behaves in the real world. The novel mouse model provides an important strategy to precisely assess the zoonotic potential (likelihood of transmission from animals to humans) of CWD and other animal prion diseases using natural routes of transmission. This will impact the tools used and direction of future studies of CWD and other prion diseases allowing more rapid and comprehensive responses to emerging questions aiding both the researchers at the producers they support…end
https://www.ars.usda.gov/research/project/?accnNo=440677&fy=202
Chronic Wasting Disease CWD vs Scrapie TSE Prion
Volume 30, Number 8—August 2024
Research
Scrapie Versus Chronic Wasting Disease in White-Tailed Deer
Zoe J. Lambert1, Jifeng Bian, Eric D. Cassmann, M. Heather West Greenlee, and Justin J. Greenlee
Author affiliations: Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee, USA (Z.J. Lambert); US Department of Agriculture, Ames, Iowa, USA (Z.J. Lambert, J. Bian, E.D. Cassmann, J.J. Greenlee); Iowa State University, Ames (Z.J. Lambert, M.H. West Greenlee) Suggested citation for this article
Abstract
White-tailed deer are susceptible to scrapie (WTD scrapie) after oronasal inoculation with the classical scrapie agent from sheep. Deer affected by WTD scrapie are difficult to differentiate from deer infected with chronic wasting disease (CWD). To assess the transmissibility of the WTD scrapie agent and tissue phenotypes when further passaged in white-tailed deer, we oronasally inoculated wild-type white-tailed deer with WTD scrapie agent. We found that WTD scrapie and CWD agents were generally similar, although some differences were noted. The greatest differences were seen in bioassays of cervidized mice that exhibited significantly longer survival periods when inoculated with WTD scrapie agent than those inoculated with CWD agent. Our findings establish that white-tailed deer are susceptible to WTD scrapie and that the presence of WTD scrapie agent in the lymphoreticular system suggests the handling of suspected cases should be consistent with current CWD guidelines because environmental shedding may occur.
snip…
The potential for zoonoses of cervid-derived PrPSc is still not well understood (6,18,45–47); however, interspecies transmission can increase host range and zoonotic potential (48–50). Therefore, to protect herds and the food supply, suspected cases of WTD scrapie should be handled the same as cases of CWD.
https://wwwnc.cdc.gov/eid/article/30/8/24-0007_article
Research Project: Elucidating the Pathobiology and Transmission of Transmissible Spongiform Encephalopathies
Location: Virus and Prion Research
Title: Differentiation of scrapie from chronic wasting disease in white-tailed deer
Author item LAMBERT, ZOE - Oak Ridge Institute For Science And Education (ORISE) item Bian, Jifeng item Cassmann, Eric item WEST GREENLEE, HEATHER - Iowa State University item Greenlee, Justin
Submitted to: Emerging Infectious Diseases Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/13/2024 Publication Date: N/A Citation: N/A
Interpretive Summary: Prion diseases are a neurodegenerative disease that can spread between animals. They are caused when the normal cellular prion protein misfolds and accumulates in the host’s central nervous system. This change is irreversible and invariably causes neurological disease and death of the host. The prion disease that affects sheep, scrapie, has been recognized for hundreds of years. However, chronic wasting disease, a similar disease found in white-tailed deer (WTD), has only been recognized since the 1960s. It has long been suggested that prion disease in deer (chronic wasting disease) was caused by the prion agent from sheep (scrapie). Recently, our lab confirmed that WTD will become infected by scrapie from sheep under conditions that mimic natural exposure. The disease produced in these animals was termed WTD scrapie. This manuscript addresses the next step in disease spread: whether sick WTD can pass WTD scrapie on to other deer. We found that white-tailed deer sick with scrapie can infect other deer under conditions mimicking natural exposure. The work reported in this manuscript demonstrates that CWD is difficult to differentiate from WTD scrapie. Regardless, WTD scrapie prions accumulate in the lymphoreticular system, meaning that environmental contamination is likely through feces, saliva, and other body fluids. Controlling WTD scrapie would require precautions similar to those taken with chronic wasting disease. The presence of WTD scrapie could confound mitigation efforts for chronic wasting disease. This information will be of interest to regulatory officials, the farmed cervid industry, and officials tasked with protecting animal health such as state Departments of Agriculture, Natural Resources, or Parks and Wildlife.
Technical Abstract: White-tailed deer (WTD) are susceptible to the scrapie agent from sheep after oronasal inoculation, termed WTD scrapie. However, results from western blotting these brainstems and lymph nodes are difficult to differentiate from WTD infected with chronic wasting disease (CWD). In order to assess the transmissibility of WTD scrapie and tissue phenotypes upon its further passage in WTD, three wildtype WTD (QQ95/GG96) were oronasally inoculated with WTD scrapie. These WTD presented with clinical signs and were euthanized between 21 and 26 months post-inoculation. Enzyme immunoassay (IDEXX) confirmed the presence of misfolded prion protein in the central nervous and lymphoreticular systems of all WTD in the study. Immunohistochemical staining, western blotting, and conformational stabilities were generally similar between the misfolded prion protein of WTD scrapie and CWD, though some differences were noted. Specifically, intraneuronal accumulation of misfolded prion protein was present in retinal ganglion cells of a WTD with WTD scrapie, not CWD. Additionally, epitope mapping revealed that the misfolded prion protein of CWD is slightly longer than that of WTD scrapie. Strong differences were seen in bioassays of cervidized mice, which exhibit significantly longer survival periods when inoculated with WTD scrapie as compared to those inoculated with CWD. Overall, this article establishes that WTD are highly susceptible to the WTD scrapie agent. Though subtle molecular differences exist between the misfolded prion protein of WTD scrapie and CWD, the presence of WTD scrapie in the lymphoreticular system determines that suspected cases be handled consistent with current guidelines for CWD.
https://www.ars.usda.gov/research/publications/publication/?seqNo115=410511
Title: Characterization of classical sheep scrapie in white-tailed deer after experimental oronasal exposure
Author item Greenlee, Justin item MOORE, SARAH - Orise Fellow item Cassmann, Eric item LAMBERT, ZOE - Orise Fellow item Kokemuller, Robyn item Smith, Jodi item Kunkle, Robert item KONG, QINGZHONG - Case Western Reserve University (CWRU) item WEST GREENLEE, HEATHER - Iowa State University
Submitted to: Journal of Infectious Diseases Publication Type: Peer Reviewed Journal Publication Acceptance Date: 11/4/2022 Publication Date: 11/8/2022
Citation: Greenlee, J.J., Moore, S.J., Cassmann, E.D., Lambert, Z.J., Kokemuller, R., Smith, J.D., Kunkle, R.A., Kong, Q., West Greenlee, H.M. 2022. Characterization of classical sheep scrapie in white-tailed deer after experimental oronasal exposure. Journal of Infectious Diseases. 227(12):1386-1395. Article jiac443. https://doi.org/10.1093/infdis/jiac443.
DOI: https://doi.org/10.1093/infdis/jiac443
Interpretive Summary: Chronic Wasting Disease (CWD), a fatal neurodegenerative disease that occurs in farmed and wild cervids (deer and elk) of North America, is a transmissible spongiform encephalopathy (TSE). TSEs are caused by infectious proteins called prions that are resistant to decontamination and environmental degradation. The origin of chronic wasting disease is not known, but it has many similarities to the TSE of sheep called scrapie. It has long been hypothesized that CWD could have arisen through transmission of sheep scrapie to deer. The purpose of this study was to determine if scrapie derived from sheep could be transmitted to white-tailed deer. This study reports that the deer inoculated with sheep scrapie developed clinical signs of TSE and that the abnormal prion protein could be detected in a wide range of neural and lymphoid tissues. These results indicate that deer may be susceptible to sheep scrapie if exposed to the disease in natural or agricultural settings . In addition, several strong similarities between CWD in white-tailed deer and the experimental cases of scrapie in white-tailed deer in this report suggest that it would be difficult to identify scrapie in deer were a case to occur. This information should be considered when developing plans to reduce or eliminate TSEs or advising farmers that wish to keep their deer herds free from prion diseases.
Technical Abstract: Scrapie is a prion disease of sheep and goats that is associated with widespread accumulation of abnormal prion protein (PrPSc) in the central nervous and lymphoid tissues. Chronic wasting disease (CWD) is the natural prion disease of cervid species and is similar to scrapie in sheep. The purpose of this study was to determine susceptibility of white-tailed deer (WTD) to the scrapie agent. We inoculated WTD (n=5) by a concurrent oral and intranasal exposure with the scrapie agent from sheep and (n=6) with the scrapie agent from goats. All deer exposed to the agent of scrapie from sheep had evidence of PrPSc accumulation. PrPSc was detected in lymphoid tissues at preclinical time points, and deer necropsied after 28 months post-inoculation had clinical signs, spongiform lesions, and widespread distribution of PrPSc in neural and lymphoid tissues. Western blots done on samples from the brainstem, cerebellum, and lymph nodes of scrapie-infected WTD have a molecular profile similar to CWD and distinct from western blots of samples from the cerebral cortex, retina, or the original sheep scrapie inoculum. WTD are susceptible to the agent of scrapie from sheep and differentiation from CWD may be difficult.
https://www.ars.usda.gov/research/publications/publication/?seqNo115=336834
please see;
SCRAPIE TSE Prion USA RAPID RESPONSE URGENT UPDATES DECEMBER 25, 2025
https://scrapie-usa.blogspot.com/2025/12/scrapie-tse-prion-usa-rapid-response.html
https://prpsc.proboards.com/thread/186/scrapie-prion-response-urgent-updates
2026 USDA EXPLANATORY NOTES, APHIS, CWD, BSE, Scrapie, TSE, Prion
https://transmissiblespongiformencephalopathy.blogspot.com/2025/12/2026-usda-explanatory-notes-aphis-cwd.html
https://transmissiblespongiformencephalopathy.blogspot.com/2025/12/2026-usda-explanatory-notes-aphis-cwd.html
ARS Research Elucidating the Pathobiology and Transmission of Transmissible Spongiform Encephalopathies 2025 Annual Report
CWD, transmission to, Cattle, Sheep, Pigs, Cervid, oh my!
Price of TSE Prion Poker Goes Up Again…terry
https://transmissiblespongiformencephalopathy.blogspot.com/2025/12/ars-research-elucidating-pathobiology.html
APHIS USDA Captive CWD Herds Update by State December 2025 Update
CHRONIC WASTING DISEASE CASES
https://www.aphis.usda.gov/sites/default/files/status-of-captive-herds.pdf
APHIS USDA Captive CWD Herds Update by State December 2025 Update
https://chronic-wasting-disease.blogspot.com/2025/12/aphis-usda-captive-cwd-herds-update-by.html
https://prpsc.proboards.com/thread/187/aphis-captive-herds-update-december
O.05: Transmission of prions to primates after extended silent incubation periods: Implications for BSE and scrapie risk assessment in human populations
*** We recently observed the direct transmission of a natural classical scrapie isolate to macaque after a 10-year silent incubation period,
***with features similar to some reported for human cases of sporadic CJD, albeit requiring fourfold long incubation than BSE. Scrapie, as recently evoked in humanized mice (Cassard, 2014),
***is the third potentially zoonotic PD (with BSE and L-type BSE),
***thus questioning the origin of human sporadic cases.
==============
PRION 2015 CONFERENCE
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5019500/
PRION 2016 TOKYO
Saturday, April 23, 2016
SCRAPIE WS-01: Prion diseases in animals and zoonotic potential 2016
Prion. 10:S15-S21. 2016 ISSN: 1933-68961933-690X
WS-01: Prion diseases in animals and zoonotic potential
“Transmission of the different scrapie isolates in these mice leads to the emergence of prion strain phenotypes that showed similar characteristics to those displayed by MM1 or VV2 sCJD prion.”
These results demonstrate that scrapie prions have a zoonotic potential and raise new questions about the possible link between animal and human prions.
http://www.tandfonline.com/doi/abs/10.1080/19336896.2016.1163048?journalCode=kprn20
Increased Atypical Scrapie Detections
Press reports indicate that increased surveillance is catching what otherwise would have been unreported findings of atypical scrapie in sheep. In 2009, five new cases have been reported in Quebec, Ontario, Alberta, and Saskatchewan. With the exception of Quebec, all cases have been diagnosed as being the atypical form found in older animals. Canada encourages producers to join its voluntary surveillance program in order to gain scrapie-free status. The World Animal Health will not classify Canada as scrapie-free until no new cases are reported for seven years. The Canadian Sheep Federation is calling on the government to fund a wider surveillance program in order to establish the level of prevalence prior to setting an eradication date. Besides long-term testing, industry is calling for a compensation program for farmers who report unusual deaths in their flocks.
http://gain.fas.usda.gov/Recent%20GAIN%20Publications/This%20Week%20in%20Canadian%20Agriculture%20%20%20%20%20Issue%2028_Ottawa_Canada_11-6-2009.pdf
Published: 04 October 2023
Detection of classical BSE prions in asymptomatic cows after inoculation with atypical/Nor98 scrapie
Marina Betancor, Belén MarÃn, Alicia Otero, Carlos Hedman, Antonio Romero, Tomás Barrio, Eloisa Sevilla, Jean-Yves Douet, Alvina Huor, Juan José Badiola, Olivier Andréoletti & Rosa Bolea Veterinary Research volume 54, Article number: 89 (2023) Cite this article
Abstract
The emergence of bovine spongiform encephalopathy (BSE) prions from atypical scrapie has been recently observed upon experimental transmission to rodent and swine models. This study aimed to assess whether the inoculation of atypical scrapie could induce BSE-like disease in cattle. Four calves were intracerebrally challenged with atypical scrapie. Animals were euthanized without clinical signs of prion disease and tested negative for PrPSc accumulation by immunohistochemistry and western blotting. However, an emergence of BSE-like prion seeding activity was detected during in vitro propagation of brain samples from the inoculated animals. These findings suggest that atypical scrapie may represent a potential source of BSE infection in cattle.
Snip…
Discussion
Previous studies have demonstrated that C-BSE prions can be present as a minor variant in ovine atypical scrapie isolates and that C-BSE can emerge during the passage of these isolates to pigs and bovine PrP mice [7, 8]. These results pointed to atypical scrapie as a possible origin of C-BSE. Therefore, this study was meant to assess the link between atypical scrapie and C-BSE in the natural host of C-BSE, cattle. Although the intracerebral challenge has some limitations and does not reflect the natural transmission process of prions, bioassays using experimental prion inoculation have allowed to identify and describe the transmission mechanisms of these pathogens. Therefore, we decided to challenge cattle with an atypical scrapie isolate.
It is important to note that none of the animals in this study showed any clinical signs of TSE after inoculation with atypical scrapie, according to the results previously obtained in pigs [8]. In addition, the absence of spongiform changes in brain sections, as well as the absence of PrPSc accumulation by conventional techniques in brain areas from the atypical scrapie-inoculated cows, further highlights the need for highly sensitive techniques such as PMCA to detect low levels of prions. After the in vitro propagation of brain samples from the cows included in this study, seeding activity was detected in reactions seeded with brain material from three out of the four cows, in the areas of frontal cortex, thalamus, and/or cerebellum. Interestingly, none of the samples from the obex, which is one of the most affected areas in prion diseases [14], showed seeding activity. Importantly, the observed glycosylation pattern of the positive PMCA reactions was indistinguishable from that of C-BSE prions and PMCA products from reactions seeded with C-BSE prions. To check whether C-BSE-like prions were present in the original atypical scrapie isolate or if they emerged in the brain of the cows after the inoculation, we performed PMCA of the original inoculum in TgBov substrate, following the same conditions described above. The in vitro amplification of the atypical scrapie inoculum resulted in the propagation of BSE-like seeding activity, biochemically indistinguishable from C-BSE or positive PMCA reactions seeded with brain samples from the inoculated cows, suggesting that, as described before, certain atypical scrapie isolates contain low levels of C-BSE prions [9].
Moreover, in order to rule out a spontaneous in vitro misfolding of bovine PrP during PMCA, we included, as a control for the technique, brain samples from non-inoculated age-matching cows that were also subjected to serial in vitro propagation in TgBov substrate. No positivity was observed in PMCA reactions seeded with samples from these animals, suggesting a true C-BSE-like prion seeding activity and not a spontaneous in vitro misfolding of PrP.
All these results suggest the amplification of C-BSE-like prions during the transmission of ovine atypical scrapie to cows. It is true that, in order to confirm the presence of infectious BSE prions in the challenged cows, strain typing experiments of the PMCA products should be carried out in established mouse lines. Therefore, studies involving a bioassay in bovine and ovine PrP-expressing mice have been started.
Interestingly, the time after inoculation and the BSE-like prion seeding activity were not correlated. As previously stated, the emergence of C-BSE from atypical scrapie has been associated with the presence of low levels of C-BSE prions in the atypical scrapie isolates and our results after the in vitro amplification of the PS152 inoculum support this theory. Therefore, the number of C-BSE conformers contained in the used atypical scrapie isolates may be reduced and not homogeneously distributed, making cows receiving different amounts of C-BSE-like prions. It is true that the emergence of C-BSE-like PMCA seeding activity from the brains of cows could be related to the persistence of prions from the original atypical scrapie inoculum. Previous studies, in which prion seeding activity was detected in the brain of intracerebrally inoculated PrP0/0 mice have highlighted the capacity of prions to persist in non-replicative environments [15]. Nevertheless, cows were intracerebrally challenged in the frontal cortex, and seeding activity was detected in caudal regions of their brains but not in more rostral areas such as the frontal cortex. If these positive PMCA reactions were not a bona fide propagation of C-BSE-like prions but associated to inoculum persistence, it would be expected to detect such amplification in the most rostral areas of the brain. Although all these results support a bona fide propagation of C-BSE-like prions, the possibility of PMCA detecting remaining prions of the inoculum, would be definitely ruled out after in vivo bioassays in mouse lines, which are currently being carried out.
The lack of clinical signs of prion disease in cows after inoculation with atypical scrapie contrasts with results from a previous study in which bovine PrP mice (TgBov) were challenged with atypical scrapie isolates and displayed signs of clinical prion disease, developing neuropathological characteristics of C-BSE [7]. In addition, in the mentioned study, after the first passage, signs of clinical prion disease were only observed in a low proportion of the inoculated mice, and several of the inoculated isolates did not lead to PrPSc accumulation. Three serial passages of atypical scrapie were needed to observe complete attack rates in TgBov mice. Moreover, mice from the first passage that developed clinical signs showed long incubation periods considering the lifespan of a mouse. The cows in this study were also euthanized after a long post-inoculation period (between ~7 and ~11 years). However, the number of C-BSE-like prions present in the original atypical scrapie inoculum was probably too low to produce disease in the cows upon first passage. We also need to consider that TgBov mice overexpress ~8 times bovine PrPC, making them more susceptible to develop disease after the inoculation of C-BSE prions.
Further in vivo experiments challenging different mouse lines have been started in order to confirm the infectivity of the PMCA products obtained in this study. However, in conclusion, our findings show that the propagation of atypical scrapie in cattle leads to the emergence of BSE-like seeding activity. This is a concerning issue with far-reaching implications for public health and food safety. The possibility of interspecies transmission of prion diseases and the emergence of new prion strains highlight the critical need for continued surveillance and monitoring of these diseases in both animal and human populations. Early detection of prion diseases is crucial, and highly sensitive detection techniques such as PMCA can play an important role in this regard.
https://veterinaryresearch.biomedcentral.com/articles/10.1186/s13567-023-01225-2
Subject: SCRAPIE 'USA' ANNUAL REPORT (105 __newly__ infected flocks 2002) & CWD IN USA Date: Tue, 10 Dec 2002 08:17:17 -0600 From: "Terry S. Singeltary Sr." To: flounder@wt.net Date: Mon, 9 Dec 2002 21:21:10 -0600 Reply-To: Bovine Spongiform Encephalopathy Sender: Bovine Spongiform Encephalopathy From: "Terry S. Singeltary Sr." Subject: SCRAPIE 'USA' ANNUAL REPORT (105 newly infected flocks 2002) & CWD IN USA
As of September 30, 2002, there were 45 scrapie infected and source flocks (figure 3).
There were 105 newly infected flocks, reported in FY2002 (figure 4).
In addition, 379 scrapie cases were confirmed and reported by the National Veterinary Services Laboratories (NVSL) in FY 2002 (figure 5) and (figure 6).
Five cases of scrapie in goats were reported in FY 2002 (figure 7), the last of which was confirmed in August 2002.
New infected and source flocks numbers and the number of these flocks released in FY 2002 are depicted in chart 4.
One hundred (100) flocks which is 67 percent of the scrapie infected and source flocks present in FY 2002 were released or put on clean-up plans in FY2002. Slaughter Surveillance Slaughter Surveillance is currently in Phase II which is intended to determine the prevalence of scrapie in the US culled sheep population.
Through September 2002 samples from 3,269 sheep were submitted to NVSL for testing. Samples from a total of 6,795 sheep have been submitted since the beginning of Phase II on April 1, 2002. Surveillance regions are depicted in (figure 8).
Scrapie Testing During FY 2002 11,751 animals have been tested for scrapie which includes: 2,711 regular necropsy cases, 1,343 third eyelid biopsies for the test validation project, 546 third eyelid biopsies for the regulatory program, and approximately 7,151 animals for Phase I & II of SOSS (chart 5).
Laboratory testing has been taking 10 - 11 days on average with a range of 3 - 34 days. Ear Tag Orders During FY 2002 9.9 million plastic and 6.0 million metal tags were distributed by APHIS (chart 6).
http://www.aphis.usda.gov/vs/nahps/scrapie/annual_report/annual-report.html
Classical BSE emergence from Nor98/atypical scrapie: Unraveling the shift vs. selection dichotomy in the prion field
Sara Canoyra, Alba MarÃn-Moreno, Juan Carlos Espinosa , and Juan MarÃa Torres
Authors Info & Affiliations Edited by Byron Caughey, National Institute of Allergy and Infectious Diseases (National Institutes of Health), Hamilton, MT; received January 17, 2025; accepted June 7, 2025 by Editorial Board Member Lila M. Gierasch
July 15, 2025
122 (29) e2501104122 https://doi.org/10.1073/pnas.2501104122
Significance
Classical bovine spongiform encephalopathy (c-BSE) is a fatal cattle prion disease transmissible to humans as variant Creutzfeldt–Jakob Disease (vCJD). Understanding how c-BSE emerges is crucial for preventing future outbreaks and protecting public health. Two main hypotheses explain prion adaptation during cross-species transmission: “conformational shift or deformed templating,” where the species barrier forces a change to a different pathological prion protein, and “conformational selection,” where the species barrier filters preexisting conformers. Our results demonstrate that the conformational shift mechanism explains the emergence of c-BSE when Nor98/atypical scrapie (AS) is transmitted to cattle. This is significant because AS, found in sheep and goats worldwide, can convert to c-BSE. Preventing AS from entering the food chain is crucial to reduce c-BSE/vCJD risks.
Abstract
Prion diseases can manifest with distinct phenotypes in a single species, a phenomenon known as prion strains. Upon cross-species transmission, alterations in the disease phenotype can occur, interpreted as the emergence of a new strain. Two main and non–mutually exclusive evolutionary hypotheses have been proposed to explain this phenomenon: the “conformational shift” or “deformed templating” and the “conformational selection.” The conformational shift hypothesis proposes that the introduction of a new host prion protein (PrPC) forces a change in the conformation of the pathological prion protein (PrPSc), causing the new prion strain emergence. On the contrary, the conformational selection model postulates that prion isolates are a conglomerate of PrPSc conformations with relative distribution frequencies, wherein the species barrier acts as a filter selecting the one fittest for the new species environment. Previous studies reported the emergence of the classical bovine spongiform encephalopathy agent (c-BSE) upon transmission of Nor98/atypical scrapie (AS) onto a bovine PrP. This study investigates the evolutionary dichotomy of this c-BSE emergence by using prion strain thermostability combined with protein misfolding cyclic amplification to distinguish between both strains. Our results suggest that the conformational shift could be the principal mechanism responsible for the c-BSE emergence. Furthermore, the selection model was dismissed as the key mechanism based on the analysis of an artificial c-BSE and AS mixture. The ability of the AS conformers to shift conformation to a c-BSE one supports the hypothesis that the epidemic c-BSE prion may have originated from the transmission of AS in cattle.
https://www.pnas.org/doi/abs/10.1073/pnas.2501104122?download=true
Published: 04 October 2023
Detection of classical BSE prions in asymptomatic cows after inoculation with atypical/Nor98 scrapie
Marina Betancor, Belén MarÃn, Alicia Otero, Carlos Hedman, Antonio Romero, Tomás Barrio, Eloisa Sevilla, Jean-Yves Douet, Alvina Huor, Juan José Badiola, Olivier Andréoletti & Rosa Bolea Veterinary Research volume 54, Article number: 89 (2023) Cite this article
Abstract
The emergence of bovine spongiform encephalopathy (BSE) prions from atypical scrapie has been recently observed upon experimental transmission to rodent and swine models. This study aimed to assess whether the inoculation of atypical scrapie could induce BSE-like disease in cattle. Four calves were intracerebrally challenged with atypical scrapie. Animals were euthanized without clinical signs of prion disease and tested negative for PrPSc accumulation by immunohistochemistry and western blotting. However, an emergence of BSE-like prion seeding activity was detected during in vitro propagation of brain samples from the inoculated animals. These findings suggest that atypical scrapie may represent a potential source of BSE infection in cattle.
Snip…
Discussion
Previous studies have demonstrated that C-BSE prions can be present as a minor variant in ovine atypical scrapie isolates and that C-BSE can emerge during the passage of these isolates to pigs and bovine PrP mice [7, 8]. These results pointed to atypical scrapie as a possible origin of C-BSE. Therefore, this study was meant to assess the link between atypical scrapie and C-BSE in the natural host of C-BSE, cattle. Although the intracerebral challenge has some limitations and does not reflect the natural transmission process of prions, bioassays using experimental prion inoculation have allowed to identify and describe the transmission mechanisms of these pathogens. Therefore, we decided to challenge cattle with an atypical scrapie isolate.
It is important to note that none of the animals in this study showed any clinical signs of TSE after inoculation with atypical scrapie, according to the results previously obtained in pigs [8]. In addition, the absence of spongiform changes in brain sections, as well as the absence of PrPSc accumulation by conventional techniques in brain areas from the atypical scrapie-inoculated cows, further highlights the need for highly sensitive techniques such as PMCA to detect low levels of prions. After the in vitro propagation of brain samples from the cows included in this study, seeding activity was detected in reactions seeded with brain material from three out of the four cows, in the areas of frontal cortex, thalamus, and/or cerebellum. Interestingly, none of the samples from the obex, which is one of the most affected areas in prion diseases [14], showed seeding activity. Importantly, the observed glycosylation pattern of the positive PMCA reactions was indistinguishable from that of C-BSE prions and PMCA products from reactions seeded with C-BSE prions. To check whether C-BSE-like prions were present in the original atypical scrapie isolate or if they emerged in the brain of the cows after the inoculation, we performed PMCA of the original inoculum in TgBov substrate, following the same conditions described above. The in vitro amplification of the atypical scrapie inoculum resulted in the propagation of BSE-like seeding activity, biochemically indistinguishable from C-BSE or positive PMCA reactions seeded with brain samples from the inoculated cows, suggesting that, as described before, certain atypical scrapie isolates contain low levels of C-BSE prions [9].
Moreover, in order to rule out a spontaneous in vitro misfolding of bovine PrP during PMCA, we included, as a control for the technique, brain samples from non-inoculated age-matching cows that were also subjected to serial in vitro propagation in TgBov substrate. No positivity was observed in PMCA reactions seeded with samples from these animals, suggesting a true C-BSE-like prion seeding activity and not a spontaneous in vitro misfolding of PrP.
All these results suggest the amplification of C-BSE-like prions during the transmission of ovine atypical scrapie to cows. It is true that, in order to confirm the presence of infectious BSE prions in the challenged cows, strain typing experiments of the PMCA products should be carried out in established mouse lines. Therefore, studies involving a bioassay in bovine and ovine PrP-expressing mice have been started.
Interestingly, the time after inoculation and the BSE-like prion seeding activity were not correlated. As previously stated, the emergence of C-BSE from atypical scrapie has been associated with the presence of low levels of C-BSE prions in the atypical scrapie isolates and our results after the in vitro amplification of the PS152 inoculum support this theory. Therefore, the number of C-BSE conformers contained in the used atypical scrapie isolates may be reduced and not homogeneously distributed, making cows receiving different amounts of C-BSE-like prions. It is true that the emergence of C-BSE-like PMCA seeding activity from the brains of cows could be related to the persistence of prions from the original atypical scrapie inoculum. Previous studies, in which prion seeding activity was detected in the brain of intracerebrally inoculated PrP0/0 mice have highlighted the capacity of prions to persist in non-replicative environments [15]. Nevertheless, cows were intracerebrally challenged in the frontal cortex, and seeding activity was detected in caudal regions of their brains but not in more rostral areas such as the frontal cortex. If these positive PMCA reactions were not a bona fide propagation of C-BSE-like prions but associated to inoculum persistence, it would be expected to detect such amplification in the most rostral areas of the brain. Although all these results support a bona fide propagation of C-BSE-like prions, the possibility of PMCA detecting remaining prions of the inoculum, would be definitely ruled out after in vivo bioassays in mouse lines, which are currently being carried out.
The lack of clinical signs of prion disease in cows after inoculation with atypical scrapie contrasts with results from a previous study in which bovine PrP mice (TgBov) were challenged with atypical scrapie isolates and displayed signs of clinical prion disease, developing neuropathological characteristics of C-BSE [7]. In addition, in the mentioned study, after the first passage, signs of clinical prion disease were only observed in a low proportion of the inoculated mice, and several of the inoculated isolates did not lead to PrPSc accumulation. Three serial passages of atypical scrapie were needed to observe complete attack rates in TgBov mice. Moreover, mice from the first passage that developed clinical signs showed long incubation periods considering the lifespan of a mouse. The cows in this study were also euthanized after a long post-inoculation period (between ~7 and ~11 years). However, the number of C-BSE-like prions present in the original atypical scrapie inoculum was probably too low to produce disease in the cows upon first passage. We also need to consider that TgBov mice overexpress ~8 times bovine PrPC, making them more susceptible to develop disease after the inoculation of C-BSE prions.
Further in vivo experiments challenging different mouse lines have been started in order to confirm the infectivity of the PMCA products obtained in this study. However, in conclusion, our findings show that the propagation of atypical scrapie in cattle leads to the emergence of BSE-like seeding activity. This is a concerning issue with far-reaching implications for public health and food safety. The possibility of interspecies transmission of prion diseases and the emergence of new prion strains highlight the critical need for continued surveillance and monitoring of these diseases in both animal and human populations. Early detection of prion diseases is crucial, and highly sensitive detection techniques such as PMCA can play an important role in this regard.
https://veterinaryresearch.biomedcentral.com/articles/10.1186/s13567-023-01225-2
Classical BSE prions emerge from asymptomatic pigs challenged with atypical/Nor98 scrapie
Belén MarÃn, Alicia Otero, Séverine Lugan, Juan Carlos Espinosa, Alba MarÃn-Moreno, Enric Vidal, Carlos Hedman, Antonio Romero, Martà Pumarola, Juan J. Badiola, Juan MarÃa Torres, Olivier Andréoletti & Rosa Bolea
Scientific Reports volume 11, Article number: 17428 (2021) Cite this article
Abstract
Pigs are susceptible to infection with the classical bovine spongiform encephalopathy (C-BSE) agent following experimental inoculation, and PrPSc accumulation was detected in porcine tissues after the inoculation of certain scrapie and chronic wasting disease isolates. However, a robust transmission barrier has been described in this species and, although they were exposed to C-BSE agent in many European countries, no cases of natural transmissible spongiform encephalopathies (TSE) infections have been reported in pigs. Transmission of atypical scrapie to bovinized mice resulted in the emergence of C-BSE prions. Here, we conducted a study to determine if pigs are susceptible to atypical scrapie. To this end, 12, 8–9-month-old minipigs were intracerebrally inoculated with two atypical scrapie sources. Animals were euthanized between 22- and 72-months post inoculation without clinical signs of TSE. All pigs tested negative for PrPSc accumulation by enzyme immunoassay, immunohistochemistry, western blotting and bioassay in porcine PrP mice. Surprisingly, in vitro protein misfolding cyclic amplification demonstrated the presence of C-BSE prions in different brain areas from seven pigs inoculated with both atypical scrapie isolates. Our results suggest that pigs exposed to atypical scrapie prions could become a reservoir for C-BSE and corroborate that C-BSE prions emerge during interspecies passage of atypical scrapie.
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Discussion The outbreak of C-BSE was followed by the appearance of TSE in species that had never been diagnosed with prion diseases and the emergence in humans of vCJD16,17,18. However, no natural prion disease has been described in pigs, even though they were exposed to C-BSE contaminated feed12. Posterior experimental challenges in pigs and mice expressing porcine PrP have demonstrated that, although they are not completely resistant, pigs present a robust transmission barrier for C-BSE prions4,14,19.
However, the possible transmission of a TSE to swine is a public health concern due to the wide use of pork as a source of human food, and the increasing use of pigs as tissue donors, being reported a case of vCJD in a human patient receiving a swine dura mater graft20. Although pigs are apparently non-susceptible to C-BSE after oral challenge4,5,21, infectivity has been detected in tissues from pigs orally inoculated with classical scrapie or CWD10,11. In addition, these positive orally inoculated pigs are often subclinical, what could represent a public health concern, considering that these animals could reach the slaughterhouse without showing signs suggestive of prion disease.
In the present study, we evaluated the transmissibility of atypical scrapie to pigs. Pigs were euthanized between 22- and 72-months post inoculation (mpi), and their tissues tested for PrPSc accumulation and infectivity. We did not find evidence of transmission of atypical scrapie to any of the animals by EIA (Table 2), western blotting, or mouse bioassay (Table 3). PrPSc accumulation can be detected in BSE-challenged pigs at 34 mpi4, and at 22 mpi when inoculated with SBSE7. Although scrapie or CWD-inoculated pigs do not show clinical signs, PrPSc presence can be found in scrapie-challenged animals at 51 mpi11 and as early as 6 mpi in the case of CWD10.
Our main goal was to test the ability of atypical scrapie/Nor98 strain to propagate in swine, given that mice expressing porcine PrP (PoPrP-Tg001/tgPo mice) showed to be susceptible to atypical scrapie inoculation. One atypical scrapie isolate adapted to this transgenic line, reaching a 100% attack rate and rapid incubation periods in serial passages13, a similar adaptation to that observed with the C-BSE agent19. However, when this atypical scrapie isolate was tested for propagation in tgPo mice again, together with other atypical scrapie isolates, no positive results were obtained, in vitro nor in vivo14. These results, together with the negative transmissions showed in the present study, reinforce the conclusion that porcine species is highly resistant to atypical scrapie. However, we only performed one passage in tgPo mice, and further passages in this line and/or PMCA analysis of tgPo brains to detect any possible prion replication would be of interest.
However, it was demonstrated that C-BSE prions can be present as a minor variant in ovine atypical scrapie isolates and that C-BSE can emerge during the passage of these isolates to bovine PrP mice15. Considering that the aforementioned atypical scrapie isolate also acquired BSE-like properties when transmitted to tgPo mice13, and that C-BSE is the only prion that efficiently propagates in swine PrP4,7,14, we decided to investigate whether C-BSE prions could emerge from atypical scrapie during the ovine-porcine interspecies transmission.
Interestingly, PMCA reactions seeded with brain material from 7 pigs propagated in tgBov substrate showing PrPres with identical biochemical characteristics to those of C-BSE (Fig. 1). Positive C-BSE amplification was detected in the brain of pigs inoculated with either the PS152 or TOA3 atypical scrapie isolates, at minimum incubation periods of 28- and 35-months post inoculation, respectively. From each animal, positive reactions were not obtained from all brain areas tested (Supplementary table 1). Although PrPres amplified from the pigs showed C-BSE biochemical characteristics, further bioassays in tgBov mice are required to know whether these prions replicate the neuropathological features of C-BSE.
Altogether, our results and data obtained from transmission studies of prions to pigs, tgPo mice and in vitro studies using porcine substrate have shown that pig PrP has a very limited ability to sustain prion replication. No significant polymorphisms have been described for pig PRNP22, and it has been suggested that the conformational flexibility of pig PrP sequence is very low, limiting the number of PrPSc conformations able to produce misfolding14. No differences have been found between pig and minipig PrP sequences either23, suggesting that the conclusions obtained here could be extrapolated to domestic, non-experimental pigs. However, using tgBov substrate, we have demonstrated in vitro the presence of C-BSE seeding activity in some pig brain areas, suggesting that C-BSE prions emerged during the transmission of ovine atypical scrapie prions to pigs. Interestingly, C-BSE prions did not emerge from brain material of all the pigs, and, of those from which it did emerge, it was not detected in all brarsain areas tested. No correlation between time after inoculation and BSE emergence was found either. When the emergence of C-BSE from atypical scrapie in PMCA was described, it was associated to low levels of C-BSE prions that were present in the original atypical scrapie isolates15. It is possible that this result is related to the great resistance that pigs present to prion diseases, making the penetrance of the BSE prions that could be present in the original inoculum incomplete. In addition, considering that the amount of C-BSE conformers in the atypical scrapie inocula is probably very reduced and perhaps not homogeneously distributed throughout the isolate, it is also possible that not all the pigs received a sufficient amount of C-BSE conformers capable of being detected by PMCA. Finally, we should consider that PMCA amplification of prions is sometimes a stochastic phenomenon, which could explain why no C-BSE propagation was obtained from some of the pigs. It could be also discussed that C-BSE emergence from the pig brains could be related to persistence of the original atypical scrapie inoculum. However, C-BSE amplification was not obtained from all of the pigs and, in some of them (i.e. P-1217 and P-1231) C-BSE propagation was detected in caudal regions of the brain (cerebellum or occipital cortex) but not in more rostral areas (such as parietal cortex). If C-BSE amplification from pig brain samples were associated to inoculum persistence and not bona fide propagation of C-BSE prions it would be expected that such amplification would be detected mainly in the most rostral areas of the brain. Finally, even though the titer generated was not enough to produce disease in the pigs, these results evidence again the issue that pigs could act as subclinical reservoirs for prion diseases as observed with scrapie and CWD, and that the presence of prions can be detected in pigs short after exposure to prions7,10,11.
In conclusion, our findings suggest that, although pigs present a strong transmission barrier against the propagation of atypical scrapie, they can propagate low levels of C-BSE prions. The prevalence of atypical scrapie and the presence of infectivity in tissues from atypical scrapie infected sheep are underestimated24,25. Given that pigs have demonstrated being susceptible to other prion diseases, and to propagate prions without showing signs of disease, the measures implemented to ban the inclusion of ruminant proteins in livestock feed must not be interrupted.
https://www.nature.com/articles/s41598-021-96818-2
The prevalence of atypical scrapie and the presence of infectivity in tissues from atypical scrapie infected sheep are underestimated24,25. Given that pigs have demonstrated being susceptible to other prion diseases, and to propagate prions without showing signs of disease, the measures implemented to ban the inclusion of ruminant proteins in livestock feed must not be interrupted.
https://nor-98.blogspot.com/2021/10/classical-bse-prions-emerge-from.html
EFSA atypical Scrapie
***> AS is considered more likely (subjective probability range 50–66%) that AS is a non-contagious, rather than a contagious, disease.
SNIP...SEE;
THURSDAY, JULY 8, 2021
EFSA Scientific report on the analysis of the 2‐year compulsory intensified monitoring of atypical scrapie
***> AS is considered more likely (subjective probability range 50–66%) that AS is a non-contagious, rather than a contagious, disease.
https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2021.6686
https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2021.6686
https://efsa.onlinelibrary.wiley.com/doi/epdf/10.2903/j.efsa.2021.6686
https://efsaopinionbseanimalprotein.blogspot.com/2021/07/efsa-scientific-report-on-analysis-of.html
***> Incomplete inactivation of atypical scrapie following recommended autoclave decontamination procedures <***
John Spiropoulos Richard Lockey Katy E. Beck Chris Vickery Thomas M. Holder Leigh Thorne Mark Arnold Olivier Andreoletti Marion M Simmons Linda A. Terry First published: 21 May 2019 https://doi.org/10.1111/tbed.13247 This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/tbed.13247
Summary Prions are highly resistant to the decontamination procedures normally used to inactivate conventional pathogens. This is a challenging problem not only in the medical and veterinary fields for minimising the risk of transmission from potentially infective sources, but also for ensuring the safe disposal or subsequent use of animal by‐products. Specific pressure autoclaving protocols were developed for this purpose, but different strains of prions have been reported to have differing resistance patterns to established prion decontamination procedures, and as additional TSE strains are identified it is necessary to determine the effectiveness of such procedures. In this study we assessed the efficacy of sterilisation using the EU recommended autoclave procedure for prions (133o C, 3 Bar for 20 min) on the atypical or Nor98 (AS/Nor98) scrapie strain of sheep and goats. Using a highly sensitive murine mouse model (tg338) that overexpresses ovine PrPC, we determined that this method of decontamination reduced the infectivity titre by 1010. Infectivity was nonetheless still detected after applying the recommended autoclaving protocol. This shows that AS/Nor98 can survive the designated legislative decontamination conditions, albeit with a significant decrease in titre. The infectivity of a classical scrapie isolate subjected to the same decontamination conditions was reduced by 106 suggesting that the AS/Nor98 isolate is less sensitive to decontamination than the classical scrapie source. This article is protected by copyright. All rights reserved.
https://onlinelibrary.wiley.com/doi/abs/10.1111/tbed.13247
Saturday, May 2, 2009
APHIS AND WHO PLAN TO EXEMPT THE ATYPICAL SCRAPIE NOR-98 FROM REGULATIONS AT MEETING THIS MONTH
http://nor-98.blogspot.com/2009/05/aphis-and-who-plan-to-exempt-atypical.html
Monday, November 30, 2009
USDA AND OIE COLLABORATE TO EXCLUDE ATYPICAL SCRAPIE NOR-98 ANIMAL HEALTH CODE
http://nor-98.blogspot.com/2009/11/usda-and-oie-collaborate-to-exclude.html
Thursday, December 20, 2012
OIE GROUP RECOMMENDS THAT SCRAPE PRION DISEASE BE DELISTED AND SAME OLD BSe WITH BOVINE MAD COW DISEASE
http://transmissiblespongiformencephalopathy.blogspot.com/2012/12/oie-group-recommends-that-scrape-prion.html
Experimental transmission of ovine atypical scrapie to cattle
Timm Konold, John Spiropoulos, Janet Hills, Hasina Abdul, Saira Cawthraw, Laura Phelan, Amy McKenna, Lauren Read, Sara Canoyra, Alba MarÃn-Moreno & Juan MarÃa Torres
Veterinary Research volume 54, Article number: 98 (2023)
Abstract
Classical bovine spongiform encephalopathy (BSE) in cattle was caused by the recycling and feeding of meat and bone meal contaminated with a transmissible spongiform encephalopathy (TSE) agent but its origin remains unknown. This study aimed to determine whether atypical scrapie could cause disease in cattle and to compare it with other known TSEs in cattle. Two groups of calves (five and two) were intracerebrally inoculated with atypical scrapie brain homogenate from two sheep with atypical scrapie. Controls were five calves intracerebrally inoculated with saline solution and one non-inoculated animal. Cattle were clinically monitored until clinical end-stage or at least 96 months post-inoculation (mpi). After euthanasia, tissues were collected for TSE diagnosis and potential transgenic mouse bioassay. One animal was culled with BSE-like clinical signs at 48 mpi. The other cattle either developed intercurrent diseases leading to cull or remained clinical unremarkable at study endpoint, including control cattle. None of the animals tested positive for TSEs by Western immunoblot and immunohistochemistry. Bioassay of brain samples from the clinical suspect in Ov-Tg338 and Bov-Tg110 mice was also negative. By contrast, protein misfolding cyclic amplification detected prions in the examined brains from atypical scrapie-challenged cattle, which had a classical BSE-like phenotype. This study demonstrates for the first time that a TSE agent with BSE-like properties can be amplified in cattle inoculated with atypical scrapie brain homogenate.
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This is the first study in cattle inoculated with naturally occurring scrapie isolates that found the presence of prions resembling classical BSE in bovine brain although this was limited to detection by the ultrasensitive PMCA. The results from thermostability assay confirmed that the isolates were as thermoresistant as the BSE agent as proven in other studies [36, 48]. Previous PMCA studies with various British atypical scrapie isolates did not find any evidence of amplification [49, 50]. This may be explained by the use of ovine brain as substrate rather than brain from Bov-Tg110 mice, which may facilitate conversion to classical BSE prions.
Two hypotheses for prion strain propagation in cross-species transmission experiments have been proposed: conformational selection favours a particular strain conformation out of a mixture of conformations in a scrapie isolate whilst mutation results in the conformational shift of one conformation into another [51]. Following on from the study in mice [17], it has been subsequently suggested that classical BSE properties that arise in atypical scrapie isolates transmitted to cattle may be due to conformational mutation in a new host [52]. It does not confirm that the atypical scrapie agent is the origin of the classical BSE epidemic and further transmission studies would be required to see whether classical BSE can be generated.
Would PMCA applied to brains from cattle exposed to TSE agents other than classical BSE and atypical scrapie also produce a classical BSE-like molecular phenotype? The PMCA product obtained in the thermostability test using a thermosensitive classical scrapie control showed a profile unlike classical BSE. Atypical BSE has been linked to the origin of classical BSE because of its conversion into classical BSE following serial passages in wild-type mice (L-type BSE [11]) and bovine transgenic mice (H-type BSE [53]). Although we have not tested PMCA products of atypical BSE isolates as part of this study, there is no evidence that PMCA products from atypical BSE convert into classical BSE, at least for H-type BSE using bovine brain as substrate [54]. In fact, we were unable to propagate H-type BSE using the same methodology (S Canoyra, A MarÃn-Moreno, JM Torres, unpublished observation).
The study results support the decision to maintain the current ban on animal meal in feedstuffs for ruminants, particularly as atypical scrapie occurs world-wide, and eradication is unlikely for a sporadic disease.
In summary, experimental inoculation of cattle with the atypical scrapie agent may produce clinical disease indistinguishable from classical BSE, which cannot be diagnosed by conventional diagnostic tests, but prions can be amplified by ultrasensitive tests in both clinically affected and clinically unremarkable cattle, which reveal classical BSE-like characteristics. Further studies are required to assess whether a BSE-like disease can be confirmed by conventional tests, which may initially include a second passage in cattle.
https://veterinaryresearch.biomedcentral.com/articles/10.1186/s13567-023-01224-3
Volume 17, Number 5—May 2011
Research
Experimental Oral Transmission of Atypical Scrapie to Sheep
Marion M. SimmonsComments to Author , S. Jo Moore1, Timm Konold, Lisa Thurston, Linda A. Terry, Leigh Thorne, Richard Lockey, Chris Vickery, Stephen A.C. Hawkins, Melanie J. Chaplin, and John Spiropoulos
Author affiliations: Author affiliation: Veterinary Laboratories Agency–Weybridge, Addlestone, UK Cite This Article
Abstract
To investigate the possibility of oral transmission of atypical scrapie in sheep and determine the distribution of infectivity in the animals’ peripheral tissues, we challenged neonatal lambs orally with atypical scrapie; they were then killed at 12 or 24 months. Screening test results were negative for disease-specific prion protein in all but 2 recipients; they had positive results for examination of brain, but negative for peripheral tissues. Infectivity of brain, distal ileum, and spleen from all animals was assessed in mouse bioassays; positive results were obtained from tissues that had negative results on screening. These findings demonstrate that atypical scrapie can be transmitted orally and indicate that it has the potential for natural transmission and iatrogenic spread through animal feed. Detection of infectivity in tissues negative by current surveillance methods indicates that diagnostic sensitivity is suboptimal for atypical scrapie, and potentially infectious material may be able to pass into the human food chain.
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Discussion This study is still ongoing and will not be completed until 2012. However, the current interim report documents the successful oral transmission of atypical scrapie, confirms that the disease phenotype is retained following transmission by this route in AHQ/AHQ sheep, and indicates that infectivity can be demonstrated in the gut in the absence of detectable PrPSc at least as early as 12 months after exposure.
One sheep (animal 12) culled at 24 months post inoculation displayed abnormalities in behavior and movement suggestive of atypical scrapie. Signs like ataxia with head tremor and circling have been described in experimental (19) and natural (3,30) disease, which was attributed to lesions in the cerebellum and forebrain, respectively, corresponding with PrPSc accumulation in these areas (20,24).
By contrast, animal 11, which had confirmed atypical scrapie based on postmortem tests, was considered clinically normal. The less severe and limited PrPSc accumulation in the brain of this sheep than in animal 12 may explain the absence of clinical abnormalities, which is supported by our findings in goats with scrapie in which more extensive PrPSc accumulation in the brain was usually associated with a more severe clinical disease (25).
Although all TSEs are transmissible after intracerebral challenge to a susceptible host, only some are infectious under natural conditions. Therefore, it was important from a pathogenesis and disease control perspective to establish whether or not oral transmission can be successful. However, the challenge model in this study exposed animals as neonates, when the esophageal groove is operational and the lambs are physiologically monogastric. Exposure of 3-month-old ruminating animals to similar amounts of positive brain by the oral route have so far not resulted in any clinical disease, with all animals still alive >1,500 days post challenge (M.M. Simmons, unpub. data), but most natural cases have been recorded in animals older than this, so these animals may still progress to disease in the next few years. Since this challenge study in older animals has no time-kill component, and no losses caused by unrelated disease have occurred, whether any of these sheep are in a preclinical phase of disease is unknown. Unfortunately, the absence of detectable PrPSc in lymphoreticular tissues of sheep with atypical scrapie precludes the use of biopsies to ascertain early infection in these animals.
Transmission may be more efficient in newborn animals; the incubation periods of sheep orally infected with classical scrapie were significantly shorter in sheep challenged at 14 days of age than those challenged at 6 months of age (31). If, however, oral transmission is only effective in such young animals, then field exposure would most likely have to be through milk, which is known to be a highly effective route of transmission for classical scrapie (32). No data are currently available on the potential infectivity of milk from animals with atypical scrapie.
Successful oral transmission also raises questions regarding the pathogenesis of this form of disease. There must be passage of the infectious agent from the alimentary canal to the brain through one of several possible routes, most likely those that have been suggested and discussed in detail for other TSEs, for example, retrograde neuronal transportation either directly (33–35) or through lymphoid structures or hematogenously (36). Infectivity in the absence of readily demonstrable PrPSc has been reported (37–39), and although the mouse bioassay may detect evidence of disease in other tissues, these data may not be available for at least another 2 years. More protease-sensitive forms of PrPSc may be broken down more efficiently within cells and thus do not accumulate in peripheral tissues (19), enabling atypical PrPSc to transit the digestive tract and disseminate through other systems in small amounts before accumulating detectably in the central nervous system.
Although we do not have epidemiologic evidence that supports the efficient spread of disease in the field, these data imply that disease is potentially transmissible under field situations and that spread through animal feed may be possible if the current feed restrictions were to be relaxed. Additionally, almost no data are available on the potential for atypical scrapie to transmit to other food animal species, certainly by the oral route. However, work with transgenic mice has demonstrated the potential susceptibility of pigs, with the disturbing finding that the biochemical properties of the resulting PrPSc have changed on transmission (40). The implications of this observation for subsequent transmission and host target range are currently unknown.
How reassuring is this absence of detectable PrPSc from a public health perspective? The bioassays performed in this study are not titrations, so the infectious load of the positive gut tissues cannot be quantified, although infectivity has been shown unequivocally. No experimental data are currently available on the zoonotic potential of atypical scrapie, either through experimental challenge of humanized mice or any meaningful epidemiologic correlation with human forms of TSE. However, the detection of infectivity in the distal ileum of animals as young as 12 months, in which all the tissues tested were negative for PrPSc by the currently available screening and confirmatory diagnostic tests, indicates that the diagnostic sensitivity of current surveillance methods is suboptimal for detecting atypical scrapie and that potentially infectious material may be able to pass into the human food chain undetected.
https://wwwnc.cdc.gov/eid/article/17/5/10-1654_article
See updated studies on AS
Meeting-book-final-version prion 2023 Prion 2023 Congress Organizing Committee and the NeuroPrion Association, we invite you to join us for the International Conference Prion2023 from 16-20 October 2023 in Faro, Portugal.
https://prion2023.org/wp-content/uploads/2023/10/Meeting-book-final-version2.pdf
https://web.archive.org/web/20250828201533/https://prion2023.org/wp-content/uploads/2023/10/Meeting-book-final-version2.pdf
https://www.researchgate.net/profile/Syed-Zahid-Shah/publication/378314391_Meeting-book-final-version_prion_2023/links/65d44dad28b7720cecdca95f/Meeting-book-final-version-prion-2023.pdf
AS
https://intcwdsympo.wordpress.com/wp-content/uploads/2023/06/final-agenda-with-abstracts.pdf
Abstract for Prion 2023
Title: Transmission of atypical BSE: a possible origin of Classical BSE in cattle
Authors: Sandor Dudas1, Samuel James Sharpe1, Kristina Santiago-Mateo1, Stefanie Czub1, Waqas Tahir1,2, *
Affiliation: 1National and WOAH reference Laboratory for Bovine Spongiform Encephalopathy, Canadian Food inspection Agency, Lethbridge Laboratory, Lethbridge, Canada. 2Department of Biological Sciences, University of Lethbridge, Lethbridge, Alberta, Canada.
*Corresponding and Presenting Author: waqas.tahir@inspection.gc.ca
Background: Bovine spongiform encephalopathy (BSE) is a fatal neurodegenerative disease of cattle and is categorized into classical and atypical forms. Classical BSE (CBSE) is linked to the consumption of BSE contaminated feed whereas atypical BSE is considered to be spontaneous in origin. The potential for oral transmission of atypical BSE is yet to be clearly defined.
Aims: To assess the oral transmissibility of atypical BSE (H and L type) in cattle. Should transmission be successful, determine the biochemical characteristics and distribution of PrPSc in the challenge cattle.
Material and Methods: For oral transmission, calves were fed with 100 g of either H (n=3) or L BSE (n=3) positive brain material. Two years post challenge, 1 calf from each of the H and L BSE challenge groups exhibited behavioural signs and were euthanized. Various brain regions of both animals were tested by traditional and novel prion detection methods with inconclusive results. To detect infectivity, brain homogenates from these oral challenge animals (P1) were injected intra-cranially (IC) into steer calves. Upon clinical signs of BSE, 3/4 of IC challenged steer calves were euthanized and tested for PrPSc with ELISA, immunohistochemistry and immunoblot.
Results: After 6 years of incubation, 3/4 animals (2/2 steers IC challenged with brain from P1 L-BSE oral challenge and 1/2 steer IC challenged with brain from P1 H-BSE oral challenge) developed clinical disease. Analysis of these animals revealed high levels of PrPSc in their brains, having biochemical properties similar to that of PrPSc in C-BSE.
Conclusion: These results demonstrate the oral transmission potential of atypical BSE in cattle. Surprisingly, regardless of which atypical type of BSE was used for P1 oral challenge, PrPSc in the P2 animals acquired biochemical characteristics similar to that of PrPSc in C-BSE, suggesting atypical BSE as a possible origin of C-BSE in UK.
Presentation Type: Oral Presentation
Funded by: CFIA, Health Canada, Alberta Livestock and Meat Agency, Alberta Prion
Research Institute
Grant Number: ALMA/APRI: 201400006, HC 414250
Abstract for Prion 2023
Acknowledgement: TSE unit NCAD, Lethbridge (Jianmin Yang, Sarah Bogart, Rachana Muley, Yuanmu Fang, Keri Colwell, Renee Anderson, John Gray, Rakhi Katoch) (CFIA, Canada), Dr. Catherine Graham (NSDA, Canada), Dr. Michel Levy (UCVM, Canada), Dr. Martin Groschup (FLI, Germany), Dr. Christine Fast (FLI, Germany), Dr. Bob Hills (Health Canada, Canada)
Meeting-book-final-version prion 2023 Prion 2023 Congress Organizing Committee and the NeuroPrion Association, we invite you to join us for the International Conference Prion2023 from 16-20 October 2023 in Faro, Portugal.
https://prion2023.org/wp-content/uploads/2023/10/Meeting-book-final-version2.pdf
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https://www.researchgate.net/profile/Syed-Zahid-Shah/publication/378314391_Meeting-book-final-version_prion_2023/links/65d44dad28b7720cecdca95f/Meeting-book-final-version-prion-2023.pdf
Final rule on the Importation of Sheep, Goats, and Certain Other Ruminants (APHIS-2009-0095) Scrapie, BSE, CWD, TSE Prion Singeltary Submission
https://scrapie-usa.blogspot.com/2021/12/final-rule-on-importation-of-sheep.html
CH1641 TSE Prion Update Proceedings of the Prion 2025 - Advancing the understanding and treatment of prion diseases
ISBN: 978-65-80968-48-0
https://proceedings.science/prion-2025/papers/ihc-profiling-of-brains-from-mice-inoculated-with-different-cattle-passaged-scra?lang=en
IHC profiling of brains from mice inoculated with different cattle-passaged scrapie sources
McCrory, Katrina 1Chomon-Elosua, Inigo 1Hills, Janet 1Elmer, Nicole 1Garcia-Pelayo, M. Carmen 2Konold, Timm 1Spiropoulos, John 1
Vol 1, 2025 - 329475
Abstract Prion 2025
Abstract
Introduction-To determine whether the classical BSE (C-BSE) outbreak in the UK could be related to classical scrapie (CS), cattle were inoculated with two brain pools. One brain pool was prepared from CS cases identified prior to 1975 (BP<1975) and the second consisted of CS cases detected after 1990 (BP>1990).
Objectives-To characterise the prion strain(s) that propagated in cattle challenged with the CH1641 source and study strain evolution.
Methods-Brain homogenates from cattle which were inoculated with either BP<1975 or BP>1990 were
used to inoculate transgenic mice overexpressing ovine VRQ (tg338), ovine ARQ (tgShpXI) or bovine (tg110) alleles. Attack rates (AR), incubation period (IP), lesion profiles (LP), distribution of PrPSc types in the brain (IHC pattern) and Western blot (WB) were assessed to characterise the strains that emerged.
Results & Discussion-Cattle inoculated with BP<1975 propagated very efficiently in all three mouse lines, and produced IP, LP and an IHC pattern which were indistinguishable from those produced by the CS source CH1641. Cattle inoculated with BP>1990 produced more variable results. In tg338 mice the propagation was very inefficient, (AR 0-12.5%). In tgShpXI mice AR varied from 12.5-100% with variable IP (213-625 days post inoculation). In tg110, AR was 100%. LP, IHC patterns and WB profiles are in progress.
Conclusion- After passage in cattle, BP<1975 produced a CH1641-compatible signature in all 3 mouse lines tested. The strain signatures that have emerged from cattle inoculated with BP>1990 are currently under investigation and second passages may be required to fully elucidate their signature.
https://proceedings.science/prion-2025/papers/ihc-profiling-of-brains-from-mice-inoculated-with-different-cattle-passaged-scra?lang=en
***> “Conclusion- After passage in cattle, BP<1975 produced a CH1641-compatible signature in all 3 mouse lines tested.” <***
Transmission of CH1641 in cattle
Jemma K. Thorne, Janet Hills, M. Carmen Garcia-Pelayo, Timm Konold, and John Spiropoulos Pathology and Animal Sciences Department, Animal and Plant Health Agency, Addlestone, UK
Aims: Classical BSE (C-BSE) was first identified in UK in the 1980s and is the only TSE that has proven zoonotic potential. The emergence of C-BSE was associated with a change in rendering practices implying that prions were able to escape inactivation. However, the exact origin of C-BSE remains unknown to this date although several theories have been proposed. CH1641 is a type of scrapie that biochemically is most akin to BSE. In addition CH1641 is the only scrapie type that can transmit as efficiently as C-BSE to bovinised mice (tg110) suggesting that the agent can propagate with ease on a bovine PrP background in contrast to other scrapie strains. This study was designed to investigate the transmissibility of CH1641 into cattle and characterise the resulting phenotype.
Material and Methods: To examine the ability of CH1641 to transmit to cattle, 5 animals were inoculated intracerebrally with an ovine CH1641 source. The clinical status of the animals was monitored and when they developed neurological signs they were euthanised on welfare grounds. Another 5 cattle were inoculated intracerebrally with saline solution to serve as negative, age-matched controls. Disease status was confirmed postmortem by statutory testing (Immunohistochemistry and Western blot).
Results: All CH1641 inoculated animals succumbed to clinical TSE with incubation periods 609–654 days post inoculation (dpi). One negative control died at 37 dpi and was excluded from the analysis as an intercurrent death. The remaining negative controls were killed at predetermined points to age match the CH1641 challenged cattle; they all were TSE negative. Western blot analysis revealed that in some animals the agent retained a CH1641 signature whilst in others the molecular profile acquired properties resembling C-BSE. Immunohistochemical analysis showed a similar phenotypic spectrum.
Conclusions: These preliminary data suggest that transmission of CH1641 in cattle is efficient and it results in a variable disease phenotype. Further studies are currently ongoing and include inoculation of bovinised and ovinised mice to identify if the CH1641 agent changed biological properties upon transmission to cattle. Secondary passages in cattle to investigate if intraspecies transmission can alter further the properties of the agent forcing it to converge towards C-BSE are also under consideration.
Funded by: Defra Grant number: SE1962 Acknowledgement: Pathology and Animal Science Department staff members for technical excellence PRION 2022 ABSTRACTS, AND A BIG THANK YOU TO;
On behalf of the Prion2020/2022 Congress Organizing Committee and the NeuroPrion Association, we heartily invite you to join us for the International Conference Prion2020/2022 from 13.-16. September 2022 in Göttingen.
Prion 2022 Conference abstracts: pushing the boundaries
https://www.tandfonline.com/doi/full/10.1080/19336896.2022.2091286
***> “Our transmission study demonstrates that CH 1641-like scrapie is likely to be more virulent than classical scrapie in cattle.” <***
***> “In the US, scrapie is reported primarily in sheep homozygous for 136A/171Q (AAQQ) and the disease phenotype is similar to that seen with experimental strain CH1641.” <***
http://www.ars.usda.gov/research/publications/publications.htm?seq_no_115=182469
***> Our transmission study demonstrates that CH 1641-like scrapie is likely to be more virulent than classical scrapie in cattle.
P-088 Transmission of experimental CH1641-like scrapie to bovine PrP overexpression mice
Kohtaro Miyazawa1, Kentaro Masujin1, Hiroyuki Okada1, Yuichi Matsuura1, Takashi Yokoyama2
1Influenza and Prion Disease Research Center, National Institute of Animal Health, NARO, Japan; 2Department of Planning and General Administration, National Institute of Animal Health, NARO
Introduction: Scrapie is a prion disease in sheep and goats. CH1641-lke scrapie is characterized by a lower molecular mass of the unglycosylated form of abnormal prion protein (PrpSc) compared to that of classical scrapie. It is worthy of attention because of the biochemical similarities of the Prpsc from CH1641-like and BSE affected sheep. We have reported that experimental CH1641-like scrapie is transmissible to bovine PrP overexpression (TgBoPrP) mice (Yokoyama et al. 2010). We report here the further details of this transmission study and compare the biological and biochemical properties to those of classical scrapie affected TgBoPrP mice.
Methods: The details of sheep brain homogenates used in this study are described in our previous report (Yokoyama et al. 2010). TgBoPrP mice were intracerebrally inoculated with a 10% brain homogenate of each scrapie strain. The brains of mice were subjected to histopathological and biochemical analyses.
Results: Prpsc banding pattern of CH1641-like scrapie affected TgBoPrP mice was similar to that of classical scrapie affected mice. Mean survival period of CH1641-like scrapie affected TgBoPrP mice was 170 days at the 3rd passage and it was significantly shorter than that of classical scrapie affected mice (439 days). Lesion profiles and Prpsc distributions in the brains also differed between CH1641-like and classical scrapie affected mice.
Conclusion: We succeeded in stable transmission of CH1641-like scrapie to TgBoPrP mice. Our transmission study demonstrates that CH 1641-like scrapie is likely to be more virulent than classical scrapie in cattle.
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In the US, scrapie is reported primarily in sheep homozygous for 136A/171Q (AAQQ) and the disease phenotype is similar to that seen with experimental strain CH1641.
http://www.ars.usda.gov/research/publications/publications.htm?seq_no_115=182469
OPII-1
Disease incidence and incubation period of BSE and CH1641 in sheep is associated with PrP gene polymorphisms.
Goldman W., Hunter N., Benson G., Foster J. and Hope J. | F 4 5 AFRC&MRC Neuropathogenesis Unit, Institute for Animal Health, - CO West Mains Rd. Edinburgh EH9 3JF, U.K.
The relative survival periods of mice with different Sinc genotype have long been used for scrapie strain typing. The PrP protein, a key molecule in the pathogenesis of scrapie and related diseases, is a product of the Sinc locus and homologous proteins are also linked to disease-incidence loci in sheep and man. In sheep alleles of this locus (Sip) encode several PrP protein variants, of which one has been associated with short incubation periods of Cheviot sheep infected with SSBP/1 scrapie. Other isolates, i.e. BSE or CH1641, cause a different pattern of incubation periods and a lower disease incidence in the same flock of Cheviot sheep. Using transmission to sheep of known PrP genotype as our criterion for agent strain typing, we have found a link between BSE and CH1641, a C-group strain of scrapie. Disease susceptibility of sheep to these isolates is associated with different PrP genotypes compared to SSBP/1 scrapie.
OPII-2
Transmission of Bovine Spongiform Encephalopathy in sheep, goats and mice.
Foster J., Hope J., McConnell I. and Fraser H.
Institute for Animal Health, AFRC and MRC Neuropathogenesis Unit, Kings Buildings, West - Mains Road, Edinburgh EH9 3JF
Bovine Spongiform Encephalopathy (BSE) has been transmitted in two lines of genetically selected sheep {differing in their susceptibilities to the SSBP/1 source of scrapie}, and to goats by intracerebral injection and by oral dosing. Incubation periods in sheep for both routes of challenge ranged from 440-994 days. In goats this range was 506-1508days. Both routes of infection in sheep and goats were almost equally efficient. In mice, primary transmission of BSE identified a sinc-independant genetic control of incubation period. Also, intermediate passage of BSE in sheep or goats did not alter these primary transmission properties. Hamsters were susceptible to BSE only after intervening passage through mice.
http://web.archive.org/web/20090506001316/http://www.bseinquiry.gov.uk/files/mb/m09/tab11.pdf
Atypical Nor98 Scrapie, Atypical BSE, CWD, Can Emerge As Different TSE PrP In Cross Species Transmission, A Volatile Situation For Human and Animal Health
Research Project: Pathobiology, Genetics, and Detection of Transmissible Spongiform Encephalopathies Location: Virus and Prion Research
Title: Passage of the CWD agent through meadow voles results in increased attack rates and decreased incubation periods in raccoons
Author item MOORE, SARA JO - Orise Fellow item CARLSON, CHRISTINA - Us Geological Survey (USGS) item SCHNEIDER, JAY - Us Geological Survey (USGS) item JOHNSON, CHRISTOPHER - Us Geological Survey (USGS) item Greenlee, Justin Submitted to: Emerging Infectious Diseases Publication Type: Peer Reviewed Journal Publication Acceptance Date: 12/13/2021 Publication Date: N/A Citation: N/A Interpretive
Summary: Transmissible spongiform encephalopathies (TSEs) are a group of fatal diseases caused by the accumulation of misfolded prion protein in the brain. Several livestock species including cattle, sheep, deer, and elk are afflicted by prion diseases. In sheep the disease is called scrapie. In deer and elk, the disease is called chronic wasting disease (CWD). Due to the human consumption of cervid meat products and intermingling of various livestock species with wild cervid populations, there is significant interest in characterizing the possible host range of CWD. This study reports the successful transmission of the CWD agent to raccoons, a ubiquitous omnivore present throughout North America. In addition, passage of the CWD agent from deer through meadow voles, a scavenger present in much of the range where CWD occurs, results in changes in the biological behavior of the CWD agent when that material is used to inoculate raccoons. This research is of interest to regulatory officials or anyone interested in controlling CWD in wildlife or captive cervid herds.
Technical Abstract: Chronic wasting disease (CWD) is a naturally-occurring neurodegenerative disease of cervids. Raccoons (Procyon lotor) and meadow voles (Microtus pennsylvanicus) have previously been shown to be susceptible to CWD and their scavenging habits could expose them to environmental CWD infectivity. To investigate the potential for transmission of the agent of CWD from white-tailed deer to voles and subsequently to raccoons, we intracranially inoculated raccoons with brain homogenate from a CWD-affected white-tailed deer (CWDWtd), or derivatives of this isolate after it had been passaged through voles one or five times. We found that passage of the CWDWtd isolate through voles led to a change in the biological behavior of the CWD agent, including increased attack rates and decreased incubation periods in raccoons. A better understanding of the dynamics of cross-species transmission of CWD prions will help us to better manage and control the spread of CWD in free-ranging and farmed cervid populations.
https://www.ars.usda.gov/research/publications/publication/?seqNo115=380582
''We found that passage of the CWDWtd isolate through voles led to a change in the biological behavior of the CWD agent, including increased attack rates and decreased incubation periods in raccoons.''
Disturbing...terry
Volume 26, Number 6—June 2020
Research
Radical Change in Zoonotic Abilities of Atypical BSE Prion Strains as Evidenced by Crossing of Sheep Species Barrier in Transgenic Mice
Alba MarÃn-Moreno1, Alvina Huor1, Juan Carlos Espinosa, Jean Yves Douet, Patricia Aguilar-Calvo2, Naima Aron, Juan PÃquer, Sévérine Lugan, Patricia Lorenzo, Cecile Tillier, Hervé Cassard, Olivier Andreoletti, and Juan MarÃa TorresComments to Author Author affiliations: Centro de Investigación en Sanidad Animal, Madrid, Spain (A. MarÃn-Moreno, J.C. Espinosa, P. Aguilar-Calvo, J. PÃquer, P. Lorenzo, J.M. Torres); Interactions Hôte Agent Pathogène–École Nationale Vétérinaire de Toulouse, Toulouse, France (A. Huor, J.Y. Douet, N. Aron, S. Lugan, C. Tiller, H. Cassard, O. Andreoletti)
Abstract
Classical bovine spongiform encephalopathy (BSE) is the only zoonotic prion disease described to date. Although the zoonotic potential of atypical BSE prions have been partially studied, an extensive analysis is still needed. We conducted a systematic study by inoculating atypical BSE isolates from different countries in Europe into transgenic mice overexpressing human prion protein (PrP): TgMet129, TgMet/Val129, and TgVal129. L-type BSE showed a higher zoonotic potential in TgMet129 mice than classical BSE, whereas Val129-PrP variant was a strong molecular protector against L-type BSE prions, even in heterozygosis. H-type BSE could not be transmitted to any of the mice. We also adapted 1 H- and 1 L-type BSE isolate to sheep-PrP transgenic mice and inoculated them into human-PrP transgenic mice. Atypical BSE prions showed a modification in their zoonotic ability after adaptation to sheep-PrP producing agents able to infect TgMet129 and TgVal129, bearing features that make them indistinguishable of sporadic Creutzfeldt-Jakob disease prions.
SNIP...
Our results and those provided by other studies indicate that L-BSE adapted to a VRQ sheep sequence resemble C-BSE in its molecular features (14). Moreover, L-BSE adapted to ARQ sheep sequence and H-BSE adapted to VRQ sheep sequence generate prions similar to classical scrapie, at least in terms of PrPres glycoprofile. Therefore, in the supposed case of atypical BSE transmission to sheep, early differentiation of both atypical BSE agents from other sheep prions like classical scrapie would be difficult. Nevertheless, the combination of the low incidence of atypical BSE (because of its supposed sporadic nature) and the continued prohibition of meat and bone meal recycling ameliorates the risk for transmission to sheep.
The transmission of atypical BSEs into sheep resulted in the emergence of prions similar to types 1 and 2 sCJD in terms of mean survival times, attack rates, PrPres profile, and PrPres deposition pattern in the brain of human-PrP transgenic mice. The similarities between the sheep-adapted atypical BSE prions propagated into our human-PrP transgenic mouse lines and sCJD prions could suggest a link between them. The well-established dogma that sCJD is a spontaneous disorder unrelated to animal prion disease has been questioned in a previous study given the resemblance of scrapie prions transmitted into human transgenic mouse models to sCJD strains (26); however, the data from that study do not unequivocally establish a causative link between exposure to sheep scrapie and the subsequent appearance of sCJD in humans, and the same could apply to our findings. An alternative explanation that cannot be ruled out is that, although being different strains, only a limited number of phenotypes could be generated for the human-PrP, indicating phenotypic convergence. Updates to old epidemiologic research is needed to reconsider all these results involving a possible infectious origin of sCJD. In any case, continuing the characterization of this newly emerged prion strain would be useful to finally discarding or refuting a link with sCJD prions.
Extrapolation of results from prion transmission studies based on transgenic mice should be done with caution, especially when human susceptibility to prions is analyzed. However, our results clearly indicate that atypical BSE adaptation to an ovine-PrP sequence could modify the prion agent to potentially infect humans, showing strain features indistinguishable from those of classic sCJD prions, even though they might or might not be different agents. The supposed sporadic nature of atypical BSE makes its transmission to sheep and later to humans unlikely. However, the expanding range of TSE agents displaying the capacity to transmit in human-PrP–expressing hosts warrants the continuation of the ban on meat and bone meal recycling and underscores the ongoing need for active surveillance.
https://wwwnc.cdc.gov/eid/article/26/6/18-1790_article
Published: 28 November 2018
Interspecies transmission to bovinized transgenic mice uncovers new features of a CH1641-like scrapie isolate
Kohtaro Miyazawa, Kentaro Masujin, Yuichi Matsuura, Yoshifumi Iwamaru, Takashi Yokoyama & Hiroyuki Okada Veterinary Research volume 49, Article number: 116 (2018) Cite this article
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Abstract In animal prion diseases, including bovine spongiform encephalopathy (BSE) in cattle, chronic wasting disease in cervids, and scrapie in sheep and goats, a disease-associated isoform of prion protein (PrPd) accumulates in the brains of affected animals. Although the CH1641 scrapie isolate was experimentally established in the UK, a few natural CH1641-like scrapie cases have been reported in France and the UK. The molecular mass of the unglycosylated protease-resistant core of PrPd (PrPres) is known to be similar between CH1641-like scrapie and experimental BSE in sheep. We previously established an experimental CH1641-like scrapie isolate (Sh294) from a natural classical scrapie case. Here, we demonstrated that the Sh294 isolate was independent of both classical and atypical BSEs by cross-species transmission to bovine PrP overexpressing (TgBoPrP) mice and wild-type mice. Interestingly, we found that the Sh294 isolate altered its host range by the transmission to TgBoPrP mice, and we succeeded in the first stable reproduction of CH1641-like scrapie specific PrPres banding patterns with the ~12-kDa small C-terminal fragment in wild-type mice. This study provides new insight into the relationship between CH1641-like scrapie isolates and BSEs. In addition, interspecies transmission models such as we have demonstrated here could be a great help to investigate the origin and host range of animal prions.
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Thus, all our data demonstrate that the Sh294 isolate is independent of all three BSE strains, suggesting that CH1641-like scrapie isolates could not be candidates for the origin of BSEs. Indeed, several studies have suggested that spontaneously occurring atypical BSEs in cattle may have been the origin of C-BSE [28,29,30,31,32].
https://veterinaryresearch.biomedcentral.com/articles/10.1186/s13567-018-0611-1
***> In the US, scrapie is reported primarily in sheep homozygous for 136A/171Q (AAQQ) AND the disease phenotype is similar to that seen with experimental strain CH1641. ...see below in another study...TSS
***> Atypical BSE prions showed a modification in their zoonotic ability after adaptation to sheep-PrP producing agents able to infect TgMet129 and TgVal129, bearing features that make them indistinguishable of sporadic Creutzfeldt-Jakob disease prions.
Circulation of Nor98 Atypical Scrapie in Portuguese Sheep Confirmed by Transmission of Isolates into Transgenic Ovine ARQ-PrP Mice
Mafalda Casanova 1,2, Carla Machado 3 , Paula Tavares 4 , João Silva 3 , Christine Fast 5 , Anne Balkema-Buschmann 5 , Martin H. Groschup 5 and Leonor Orge 3,6,*
1 Histopathology Facility, Instituto Gulbenkian de Ciência (IGC), 2780-156 Oeiras, Portugal; mccasanova@igc.gulbenkian.pt 2 Veterinary Medicine Department, University of Évora, 7004-516Évora, Portugal 3 Pathology Laboratory, UEISPSA, National Institute for Agricultural and Veterinary Research (INIAV), I.P., 2780-157 Oeiras, Portugal; carlitaneves@gmail.com (C.M.); joao.silva@iniav.pt(J.S.) 4 Pathology Laboratory, UEISPSA, National Institute for Agricultural and Veterinary Research (INIAV), I.P., 4485-655 Vairão-Vila do Conde, Portugal; paula.tavares@iniav.pt 5 Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Insel Riems, 17493 Greifswald, Germany; Christine.Fast@fli.de (C.F.); Anne.Balkema-Buschmann@fli.de (A.B.-B.); martin.groschup@fli.de (M.H.G.) 6 Animal and Veterinary Research Centre (CECAV), Associate Laboratory for Animal and Veterinary Science—AL4AnimalS, University of Trás-os-Montes and Alto Douro (UTAD), 5000-801 Vila Real, Portugal * Correspondence: leonor.orge@iniav.pt
Abstract: Portugal was among the first European countries to report cases of Atypical Scrapie (ASc), the dominant form of Transmissible Spongiform Encephalopathy (TSE) in Portuguese small ruminants. Although the diagnostic phenotypes observed in Portuguese ASc cases seem identical to those described for Nor98, unequivocal identification requires TSE strain-typing using murine bioassays. In this regard, we initiated characterization of ASc isolates from sheep either homozygous for the ARQ genotype or the classical scrapie-resistant ARR genotype. Isolates from such genotypes were transmitted to TgshpXI mice expressing ovine PrPARQ. Mean incubation periods were 414 ± 58 and 483 ± 107 days in mice inoculated with AL141RQ/AF141RQ and AL141RR/AL141RR sheep isolates, respectively. Both isolates produced lesion profiles similar to French ASc Nor98 ‘discordant cases’, where vacuolation was observed in the hippocampus (G6), cerebral cortex at the thalamus (G8) level, cerebellar white matter (W1) and cerebral peduncles (W3). Immunohistochemical PrPSc deposition was observed in the hippocampus, cerebellar cortex, cerebellar white matter and cerebral peduncles in the form of aggregates and fine granules. These findings were consistent with previously reported cases of ASc Nor98 transmitted to transgenic TgshpXI mice, confirming that the ASc strain present in Portuguese sheep corresponds to ASc Nor98.
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Recent work revealed the possibility of the development of a classical-BSE (BSE-C) prion after inoculation of bovine PrP transgenic mice with ASc isolates [3]. That study found that BSE-C may be present in natural ASc isolates as a minor variant, and transmission of such isolates to transgenic bovine mice resulted in emergence of BSE-C as a dominant variant. The same phenomenon was not observed after inoculation of CSc isolates. Hence, there is concern regarding the possibility of ASc having a role in the emergence of BSE-C in cattle, and a possible role in the origin of the 1980s BSE crisis, resulting from inclusion of rendered small ruminants in cattle feed [3]. Furthermore, archival ASc isolates reveal ASc was present in the United Kingdom years before BSE [11]. Another study found oral transmission of ASc into sheep has resulted in a phenotype shift to CH1641, a classical scrapie strain showing an immunoblot profile similar to bovine BSE. Although CH1641 has not been diagnosed in Portuguese sheep as of yet, it is prudent to maintain vigilant systematic analysis of lesion profiles, PrPSc immunolabelling types and patterns, as well as PrPSc electrophoretic profiles in natural hosts for evidence of any phenotypic shift and strain conversion. Such surveillance is particularly relevant in a country such as Portugal, where, in contrast to other EU countries, ASc was first diagnosed in the absence of previous CSc cases.
https://www.mdpi.com/1422-0067/22/19/10441/pdf
The emergence of classical BSE from atypical/Nor98 scrapie
Alvina Huor, View ORCID ProfileJuan Carlos Espinosa, View ORCID ProfileEnric Vidal, Hervé Cassard, View ORCID ProfileJean-Yves Douet, Séverine Lugan, Naima Aron, View ORCID ProfileAlba MarÃn-Moreno, Patricia Lorenzo, Patricia Aguilar-Calvo, Juan Badiola, Rosa Bolea, Martà Pumarola, Sylvie L. Benestad, Leonore Orge, Alana M. Thackray, Raymond Bujdoso, View ORCID ProfileJuan-Maria Torres, and View ORCID ProfileOlivier Andreoletti
aUMR Institut National de la Recherche Agronomique (INRA)/École Nationale Vétérinaire de Toulouse (ENVT) 1225, Interactions Hôtes Agents Pathogènes, 31076 Toulouse, France;
bCentro de Investigación en Sanidad Animal–Instituto Nacional de Investigación y TecnologÃa Agraria y Alimentaria, 28130 Madrid, Spain;
cCentre de Recerca en Sanitat Animal, Universitat Autònoma de Barcelona (UAB)–Institut de Recerca i Tecnologia Agroalimentà ries, Barcelona, Spain;
dCentro de EncefalopatÃas y Enfermedades Transmisibles Emergentes, Universidad de Zaragoza, 50013 Zaragoza, Spain;
eUnit of Murine and Comparative Pathology, UAB, 08193 Barcelona, Spain;
fNorwegian Veterinary Institute, N-0106 Oslo, Norway;
gLaboratory of Pathology, National Institute for Agrarian and Veterinary Research, 2780-157 Oeiras, Portugal;
hDepartment of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, United Kingdom
PNAS December 26, 2019 116 (52) 26853-26862; first published December 16, 2019; https://doi.org/10.1073/pnas.1915737116
Edited by Michael B. A. Oldstone, Scripps Research Institute, La Jolla, CA, and approved November 15, 2019 (received for review September 11, 2019)
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Significance
The origin of transmissible BSE in cattle remains unestablished. Sheep scrapie is a potential source of this known zoonotic. Here we investigated the capacity of sheep scrapie to propagate in bovine PrP transgenic mice. Unexpectedly, transmission of atypical but not classical scrapie in bovine PrP mice resulted in propagation of classical BSE prions. Detection of prion seeding activity by in vitro protein misfolding cyclic amplification demonstrated BSE prions in the original atypical scrapie isolates. BSE prion seeding activity was also detected in ovine PrP mice inoculated with limiting dilutions of atypical scrapie. Our data demonstrate that classical BSE prions can emerge during intra- and interspecies passage of atypical scrapie and provide an unprecedented insight into the evolution of mammalian prions.
Abstract
Atypical/Nor98 scrapie (AS) is a prion disease of small ruminants. Currently there are no efficient measures to control this form of prion disease, and, importantly, the zoonotic potential and the risk that AS might represent for other farmed animal species remains largely unknown. In this study, we investigated the capacity of AS to propagate in bovine PrP transgenic mice. Unexpectedly, the transmission of AS isolates originating from 5 different European countries to bovine PrP mice resulted in the propagation of the classical BSE (c-BSE) agent. Detection of prion seeding activity in vitro by protein misfolding cyclic amplification (PMCA) demonstrated that low levels of the c-BSE agent were present in the original AS isolates. C-BSE prion seeding activity was also detected in brain tissue of ovine PrP mice inoculated with limiting dilutions (endpoint titration) of ovine AS isolates. These results are consistent with the emergence and replication of c-BSE prions during the in vivo propagation of AS isolates in the natural host. These data also indicate that c-BSE prions, a known zonotic agent in humans, can emerge as a dominant prion strain during passage of AS between different species. These findings provide an unprecedented insight into the evolution of mammalian prion strain properties triggered by intra- and interspecies passage. From a public health perspective, the presence of c-BSE in AS isolates suggest that cattle exposure to small ruminant tissues and products could lead to new occurrences of c-BSE.
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With the decline of the c-BSE epizootic in cattle and the combined increase in pressure from industry, EU authorities have begun to consider discontinuing certain TSE control measures. The abrogation of the SRM measures for small ruminants and the partial reauthorization of the use of processed animal protein, formerly known as MBM, in animal feed are part of the EU authorities’ agenda. Our observation of the presence of the c-BSE agent in AS-infected small ruminants suggests that modification of the TSE control measures could result in an increased risk of exposure to c-BSE prions for both animals and humans. Whether or not this exposure will result in further c-BSE transmission in cattle and/or humans remains an open and important question.
https://www.pnas.org/content/116/52/26853
Classical BSE prions emerge from asymptomatic pigs challenged with atypical/Nor98 scrapie
Belén MarÃn1,7, Alicia Otero1,7*, Séverine Lugan2 , Juan Carlos Espinosa3 , Alba MarÃn‑Moreno3 , EnricVidal4 , Carlos Hedman1 , Antonio Romero5 , Martà Pumarola6 , Juan J. Badiola1 , Juan MarÃaTorres3 , OlivierAndréoletti2 & Rosa Bolea1
Pigs are susceptible to infection with the classical bovine spongiform encephalopathy (C-BSE) agent following experimental inoculation, and PrPSc accumulation was detected in porcine tissues after the inoculation of certain scrapie and chronic wasting disease isolates. However, a robust transmission barrier has been described in this species and, although they were exposed to C-BSE agent in many European countries, no cases of natural transmissible spongiform encephalopathies (TSE) infections have been reported in pigs. Transmission of atypical scrapie to bovinized mice resulted in the emergence of C-BSE prions. Here, we conducted a study to determine if pigs are susceptible to atypical scrapie. To this end, 12, 8–9-month-old minipigs were intracerebrally inoculated with two atypical scrapie sources. Animals were euthanized between 22- and 72-months post inoculation without clinical signs of TSE. All pigs tested negative for PrPSc accumulation by enzyme immunoassay, immunohistochemistry, western blotting and bioassay in porcine PrP mice. Surprisingly, in vitro protein misfolding cyclic amplification demonstrated the presence of C-BSE prions in different brain areas from seven pigs inoculated with both atypical scrapie isolates. Our results suggest that pigs exposed to atypical scrapie prions could become a reservoir for C-BSE and corroborate that C-BSE prions emerge during interspecies passage of atypical scrapie.
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Discussion
The outbreak of C-BSE was followed by the appearance of TSE in species that had never been diagnosed with prion diseases and the emergence in humans of vCJD16–18. However, no natural prion disease has been described in pigs, even though they were exposed to C-BSE contaminated feed12. Posterior experimental challenges in pigs and mice expressing porcine PrP have demonstrated that, although they are not completely resistant, pigs present a robust transmission barrier for C-BSE prions4,14,19.
However, the possible transmission of a TSE to swine is a public health concern due to the wide use of pork as a source of human food, and the increasing use of pigs as tissue donors, being reported a case of vCJD in a human patient receiving a swine dura mater graf20. Although pigs are apparently non-susceptible to C-BSE after oral challenge4,5,21, infectivity has been detected in tissues from pigs orally inoculated with classical scrapie or CWD10,11. In addition, these positive orally inoculated pigs are often subclinical, what could represent a public health concern, considering that these animals could reach the slaughterhouse without showing signs suggestive of prion disease.
In the present study, we evaluated the transmissibility of atypical scrapie to pigs. Pigs were euthanized between 22- and 72-months post inoculation (mpi), and their tissues tested for PrPSc accumulation and infectivity. We did not find evidence of transmission of atypical scrapie to any of the animals by EIA (Table 2), western blotting, or mouse bioassay (Table 3). PrPSc accumulation can be detected in BSE-challenged pigs at 34 mpi4 , and at 22 mpi when inoculated with SBSE7 . Although scrapie or CWD-inoculated pigs do not show clinical signs, PrPSc presence can be found in scrapie-challenged animals at 51 mpi11 and as early as 6 mpi in the case of CWD10.
Our main goal was to test the ability of atypical scrapie/Nor98 strain to propagate in swine, given that mice expressing porcine PrP (PoPrP-Tg001/tgPo mice) showed to be susceptible to atypical scrapie inoculation. One atypical scrapie isolate adapted to this transgenic line, reaching a 100% attack rate and rapid incubation periods in serial passages13, a similar adaptation to that observed with the C-BSE agent19. However, when this atypical scrapie isolate was tested for propagation in tgPo mice again, together with other atypical scrapie isolates, no positive results were obtained, in vitro nor in vivo14. These results, together with the negative transmissions showed in the present study, reinforce the conclusion that porcine species is highly resistant to atypical scrapie. However, we only performed one passage in tgPo mice, and further passages in this line and/or PMCA analysis of tgPo brains to detect any possible prion replication would be of interest.
However, it was demonstrated that C-BSE prions can be present as a minor variant in ovine atypical scrapie isolates and that C-BSE can emerge during the passage of these isolates to bovine PrP mice15. Considering that the aforementioned atypical scrapie isolate also acquired BSE-like properties when transmitted to tgPo mice13, and that C-BSE is the only prion that efficiently propagates in swine PrP4,7,14, we decided to investigate whether C-BSE prions could emerge from atypical scrapie during the ovine-porcine interspecies transmission.
Interestingly, PMCA reactions seeded with brain material from 7 pigs propagated in tgBov substrate showing PrPres with identical biochemical characteristics to those of C-BSE (Fig. 1). Positive C-BSE amplification was detected in the brain of pigs inoculated with either the PS152 or TOA3 atypical scrapie isolates, at minimum incubation periods of 28- and 35-months post inoculation, respectively. From each animal, positive reactions were not obtained from all brain areas tested (Supplementary table 1). Although PrPres amplified from the pigs showed C-BSE biochemical characteristics, further bioassays in tgBov mice are required to know whether these prions replicate the neuropathological features of C-BSE.
Altogether, our results and data obtained from transmission studies of prions to pigs, tgPo mice and in vitro studies using porcine substrate have shown that pig PrP has a very limited ability to sustain prion replication. No significant polymorphisms have been described for pig PRNP22, and it has been suggested that the conformational flexibility of pig PrP sequence is very low, limiting the number of PrPSc conformations able to produce misfolding14. No differences have been found between pig and minipig PrP sequences either23, suggesting that the conclusions obtained here could be extrapolated to domestic, non-experimental pigs. However, using tgBov substrate, we have demonstrated in vitro the presence of C-BSE seeding activity in some pig brain areas, suggesting that C-BSE prions emerged during the transmission of ovine atypical scrapie prions to pigs. Interestingly, C-BSE prions did not emerge from brain material of all the pigs, and, of those from which it did emerge, it was not detected in all brain areas tested. No correlation between time after inoculation and BSE emergence was found either. When the emergence of C-BSE from atypical scrapie in PMCA was described, it was associated to low levels of C-BSE prions that were present in the original atypical scrapie isolates15. It is possible that this result is related to the great resistance that pigs present to prion diseases, making the penetrance of the BSE prions that could be present in the original inoculum incomplete. In addition, considering that the amount of C-BSE conformers in the atypical scrapie inocula is probably very reduced and perhaps not homogeneously distributed throughout the isolate, it is also possible that not all the pigs received a sufficient amount of C-BSE conformers capable of being detected by PMCA. Finally, we should consider that PMCA amplification of prions is sometimes a stochastic phenomenon, which could explain why no C-BSE propagation was obtained from some of the pigs. It could be also discussed that C-BSE emergence from the pig brains could be related to persistence of the original atypical scrapie inoculum. However, C-BSE amplification was not obtained from all of the pigs and, in some of them (i.e. P-1217 and P-1231) C-BSE propagation was detected in caudal regions of the brain (cerebellum or occipital cortex) but not in more rostral areas (such as parietal cortex). If C-BSE amplification from pig brain samples were associated to inoculum persistence and not bona fide propagation of C-BSE prions it would be expected that such amplification would be detected mainly in the most rostral areas of the brain. Finally, even though the titer generated was not enough to produce disease in the pigs, these results evidence again the issue that pigs could act as subclinical reservoirs for prion diseases as observed with scrapie and CWD, and that the presence of prions can be detected in pigs short after exposure to prions7,10,11.
In conclusion, our findings suggest that, although pigs present a strong transmission barrier against the propagation of atypical scrapie, they can propagate low levels of C-BSE prions. The prevalence of atypical scrapie and the presence of infectivity in tissues from atypical scrapie infected sheep are underestimated24,25. Given that pigs have demonstrated being susceptible to other prion diseases, and to propagate prions without showing signs of disease, the measures implemented to ban the inclusion of ruminant proteins in livestock feed must not be interrupted.
https://hal.inrae.fr/hal-03352651/document
https://www.nature.com/articles/s41598-021-96818-2.pdf
Research Project: Pathobiology, Genetics, and Detection of Transmissible Spongiform Encephalopathies Location: Virus and Prion Research
Title: Experimental transmission of the chronic wasting disease agent to swine after oral or intracranial inoculation
Author item MOORE, SARAH - Orise Fellow item WEST GREENLEE, M - Iowa State University item KONDRU, NAVEEN - Iowa State University item MANNE, SIREESHA - Iowa State University item Smith, Jodi item Kunkle, Robert item KANTHASAMY, ANUMANTHA - Iowa State University item Greenlee, Justin Submitted to: Journal of Virology Publication Type: Peer Reviewed Journal Publication Acceptance Date: 7/6/2017 Publication Date: 9/12/2017
Citation: Moore, S.J., West Greenlee, M.H., Kondru, N., Manne, S., Smith, J.D., Kunkle, R.A., Kanthasamy, A., Greenlee, J.J. 2017. Experimental transmission of the chronic wasting disease agent to swine after oral or intracranial inoculation. Journal of Virology. 91(19):e00926-17. https://doi.org/10.1128/JVI.00926-17.
Interpretive Summary: Chronic wasting disease (CWD) is a fatal disease of wild and captive deer and elk that causes damaging changes in the brain. The infectious agent is an abnormal protein called a prion that has misfolded from its normal state. Whether CWD can transmit to swine is unknown. This study evaluated the potential of pigs to develop CWD after either intracranial or oral inoculation. Our data indicates that swine do accumulate the abnormal prion protein associated with CWD after intracranial or oral inoculation. Further, there was evidence of abnormal prion protein accumulation in lymph nodes. Currently, swine rations in the U.S. could contain animal derived components including materials from deer or elk. In addition, feral swine could be exposed to infected carcasses in areas where CWD is present in wildlife populations. This information is useful to wildlife managers and individuals in the swine and captive cervid industries. These findings could impact future regulations for the disposal of offal from deer and elk slaughtered in commercial operations. U.S. regulators should carefully consider the new information from this study before relaxing feed ban standards designed to control potentially feed borne prion diseases.
Technical Abstract: Chronic wasting disease (CWD) is a naturally occurring, fatal neurodegenerative disease of cervids. The potential for swine to serve as a host for the agent of chronic wasting disease is unknown. The purpose of this study was to investigate the susceptibility of swine to the CWD agent following oral or intracranial experimental inoculation. Crossbred piglets were assigned to one of three groups: intracranially inoculated (n=20), orally inoculated (n=19), or non-inoculated (n=9). At approximately the age at which commercial pigs reach market weight, half of the pigs in each group were culled ('market weight' groups). The remaining pigs ('aged' groups) were allowed to incubate for up to 73 months post inoculation (MPI). Tissues collected at necropsy were examined for disease-associated prion protein (PrPSc) by western blotting (WB), antigen-capture immunoassay (EIA), immunohistochemistry (IHC) and in vitro real-time quaking induced conversion (RT-QuIC). Brain samples from selected pigs were also bioassayed in mice expressing porcine prion protein. Four intracranially inoculated aged pigs and one orally inoculated aged pig were positive by EIA, IHC and/or WB. Using RT-QuIC, PrPSc was detected in lymphoid and/or brain tissue from pigs in all inoculated groups. Bioassay was positive in 4 out of 5 pigs assayed. This study demonstrates that pigs can serve as hosts for CWD, though with scant PrPSc accumulation requiring sensitive detection methods. Detection of infectivity in orally inoculated pigs using mouse bioassay raises the possibility that naturally exposed pigs could act as a reservoir of CWD infectivity.
https://www.ars.usda.gov/research/publications/publication/?seqNo115=339093
12 September 2017
Experimental Transmission of the Chronic Wasting Disease Agent to Swine after Oral or Intracranial Inoculation
Authors: S. Jo Moore, M. Heather West Greenlee, Naveen Kondru, Sireesha Manne, Jodi D. Smith, Robert A. Kunkle, Anumantha Kanthasamy, and Justin J. Greenlee
https://orcid.org/0000-0003-2202-3054
AUTHORS INFO & AFFILIATIONS
DOI: https://doi.org/10.1128/JVI.00926-17
Volume 91, Number 19
1 October 2017
ABSTRACT
ABSTRACT
Chronic wasting disease (CWD) is a naturally occurring, fatal neurodegenerative disease of cervids. The potential for swine to serve as hosts for the agent of CWD is unknown. The purpose of this study was to investigate the susceptibility of swine to the CWD agent following experimental oral or intracranial inoculation. Crossbred piglets were assigned to three groups, intracranially inoculated (n = 20), orally inoculated (n = 19), and noninoculated (n = 9). At approximately the age at which commercial pigs reach market weight, half of the pigs in each group were culled (“market weight” groups). The remaining pigs (“aged” groups) were allowed to incubate for up to 73 months postinoculation (mpi). Tissues collected at necropsy were examined for disease-associated prion protein (PrPSc) by Western blotting (WB), antigen capture enzyme immunoassay (EIA), immunohistochemistry (IHC), and in vitro real-time quaking-induced conversion (RT-QuIC). Brain samples from selected pigs were also bioassayed in mice expressing porcine prion protein. Four intracranially inoculated aged pigs and one orally inoculated aged pig were positive by EIA, IHC, and/or WB. By RT-QuIC, PrPSc was detected in lymphoid and/or brain tissue from one or more pigs in each inoculated group. The bioassay was positive in four out of five pigs assayed. This study demonstrates that pigs can support low-level amplification of CWD prions, although the species barrier to CWD infection is relatively high. However, detection of infectivity in orally inoculated pigs with a mouse bioassay raises the possibility that naturally exposed pigs could act as a reservoir of CWD infectivity. IMPORTANCE We challenged domestic swine with the chronic wasting disease agent by inoculation directly into the brain (intracranially) or by oral gavage (orally). Disease-associated prion protein (PrPSc) was detected in brain and lymphoid tissues from intracranially and orally inoculated pigs as early as 8 months of age (6 months postinoculation). Only one pig developed clinical neurologic signs suggestive of prion disease. The amount of PrPSc in the brains and lymphoid tissues of positive pigs was small, especially in orally inoculated pigs. Regardless, positive results obtained with orally inoculated pigs suggest that it may be possible for swine to serve as a reservoir for prion disease under natural conditions.
https://journals.asm.org/doi/10.1128/JVI.00926-17
Research Project: TRANSMISSION, DIFFERENTIATION, AND PATHOBIOLOGY OF TRANSMISSIBLE SPONGIFORM ENCEPHALOPATHIES Location: Virus and Prion Research
Title: Disease-associated prion protein detected in lymphoid tissues from pigs challenged with the agent of chronic wasting disease
Conclusions: This study demonstrates that PrPSc accumulates in lymphoid tissues from pigs challenged intracranially or orally with the CWD agent, and can be detected as early as 4 months after challenge. CWD-infected pigs rarely develop clinical disease and if they do, they do so after a long incubation period. This raises the possibility that CWD-infected pigs could shed prions into their environment long before they develop clinical disease. Furthermore, lymphoid tissues from CWD-infected pigs could present a potential source of CWD infectivity in the animal and human food chains.
https://www.ars.usda.gov/research/publications/publication/?seqNo115=337105
https://www.ars.usda.gov/research/publications/publication/?seqNo115=326166
Research Project: Pathobiology, Genetics, and Detection of Transmissible Spongiform Encephalopathies Location: Virus and Prion Research
Title: The agent of chronic wasting disease from pigs is infectious in transgenic mice expressing human PRNP
Author item MOORE, S - Orise Fellow item Kokemuller, Robyn item WEST-GREENLEE, M - Iowa State University item BALKEMA-BUSCHMANN, ANNE - Friedrich-Loeffler-institut item GROSCHUP, MARTIN - Friedrich-Loeffler-institut item Greenlee, Justin Submitted to: Prion Publication Type: Abstract Only Publication Acceptance Date: 5/10/2018 Publication Date: 5/22/2018 Citation: Moore, S.J., Kokemuller, R.D., West-Greenlee, M.H., Balkema-Buschmann, A., Groschup, M.H., Greenlee, J.J. 2018. The agent of chronic wasting disease from pigs is infectious in transgenic mice expressing human PRNP. Prion 2018, Santiago de Compostela, Spain, May 22-25, 2018. Paper No. WA15, page 44.
Interpretive Summary:
The successful transmission of pig-passaged CWD to Tg40 mice reported here suggests that passage of the CWD agent through pigs results in a change of the transmission characteristics which reduces the transmission barrier of Tg40 mice to the CWD agent. If this biological behavior is recapitulated in the original host species, passage of the CWD agent through pigs could potentially lead to increased pathogenicity of the CWD agent in humans.
https://www.ars.usda.gov/research/publications/publication/?seqNo115=353091
cwd scrapie pigs oral routes
***> However, at 51 months of incubation or greater, 5 animals were positive by one or more diagnostic methods. Furthermore, positive bioassay results were obtained from all inoculated groups (oral and intracranial; market weight and end of study) suggesting that swine are potential hosts for the agent of scrapie. <***
*** Although the current U.S. feed ban is based on keeping tissues from TSE infected cattle from contaminating animal feed, swine rations in the U.S. could contain animal derived components including materials from scrapie infected sheep and goats. These results indicating the susceptibility of pigs to sheep scrapie, coupled with the limitations of the current feed ban, indicates that a revision of the feed ban may be necessary to protect swine production and potentially human health. <***
***> Results: PrPSc was not detected by EIA and IHC in any RPLNs. All tonsils and MLNs were negative by IHC, though the MLN from one pig in the oral <6 month group was positive by EIA. PrPSc was detected by QuIC in at least one of the lymphoid tissues examined in 5/6 pigs in the intracranial <6 months group, 6/7 intracranial >6 months group, 5/6 pigs in the oral <6 months group, and 4/6 oral >6 months group. Overall, the MLN was positive in 14/19 (74%) of samples examined, the RPLN in 8/18 (44%), and the tonsil in 10/25 (40%).
***> Conclusions: This study demonstrates that PrPSc accumulates in lymphoid tissues from pigs challenged intracranially or orally with the CWD agent, and can be detected as early as 4 months after challenge. CWD-infected pigs rarely develop clinical disease and if they do, they do so after a long incubation period. This raises the possibility that CWD-infected pigs could shed prions into their environment long before they develop clinical disease. Furthermore, lymphoid tissues from CWD-infected pigs could present a potential source of CWD infectivity in the animal and human food chains.
https://www.ars.usda.gov/research/publications/publication/?seqNo115=353091
https://www.ars.usda.gov/research/project/?accnNo=432011&fy=2017
https://www.ars.usda.gov/research/publications/publication/?seqNo115=337105
CONFIDENTIAL
EXPERIMENTAL PORCINE SPONGIFORM ENCEPHALOPATHY
LINE TO TAKE
3. If questions on pharmaceuticals are raised at the Press conference, the suggested line to take is as follows:-
"There are no medicinal products licensed for use on the market which make use of UK-derived porcine tissues with which any hypothetical “high risk" ‘might be associated. The results of the recent experimental work at the CSM will be carefully examined by the CSM‘s Working Group on spongiform encephalopathy at its next meeting.
DO Hagger RM 1533 MT Ext 3201
http://web.archive.org/web/20030822054419/www.bseinquiry.gov.uk/files/yb/1990/09/21009001.pdf
While this clearly is a cause for concern we should not jump to the conclusion that this means that pigs will necessarily be infected by bone and meat meal fed by the oral route as is the case with cattle. ...
http://web.archive.org/web/20031026000118/www.bseinquiry.gov.uk/files/yb/1990/08/23004001.pdf
we cannot rule out the possibility that unrecognised subclinical spongiform encephalopathy could be present in British pigs though there is no evidence for this: only with parenteral/implantable pharmaceuticals/devices is the theoretical risk to humans of sufficient concern to consider any action.
http://web.archive.org/web/20030822031154/www.bseinquiry.gov.uk/files/yb/1990/09/10007001.pdf
May I, at the outset, reiterate that we should avoid dissemination of papers relating to this experimental finding to prevent premature release of the information. ...
http://web.archive.org/web/20030822052332/www.bseinquiry.gov.uk/files/yb/1990/09/11005001.pdf
3. It is particularly important that this information is not passed outside the Department, until Ministers have decided how they wish it to be handled. ...
http://web.archive.org/web/20030822052438/www.bseinquiry.gov.uk/files/yb/1990/09/12002001.pdf
But it would be easier for us if pharmaceuticals/devices are not directly mentioned at all. ...
http://web.archive.org/web/20030518170213/www.bseinquiry.gov.uk/files/yb/1990/09/13004001.pdf
Our records show that while some use is made of porcine materials in medicinal products, the only products which would appear to be in a hypothetically ''higher risk'' area are the adrenocorticotrophic hormone for which the source material comes from outside the United Kingdom, namely America China Sweden France and Germany. The products are manufactured by Ferring and Armour. A further product, ''Zenoderm Corium implant'' manufactured by Ethicon, makes use of porcine skin - which is not considered to be a ''high risk'' tissue, but one of its uses is described in the data sheet as ''in dural replacement''. This product is sourced from the United Kingdom.....
http://web.archive.org/web/20030822054419/www.bseinquiry.gov.uk/files/yb/1990/09/21009001.pdf
Emerg Infect Dis. 2009 Aug; 15(8): 1214–1221. doi: 10.3201/eid1508.081218 PMCID: PMC2815954 PMID: 19751582
Transgenic Mice Expressing Porcine Prion Protein Resistant to Classical Scrapie but Susceptible to Sheep Bovine Spongiform Encephalopathy and Atypical Scrapie
Juan-Carlos Espinosa, 1 MarÃa-Eugenia Herva, 1 Olivier Andréoletti, Danielle Padilla, Caroline Lacroux, Hervé Cassard, Isabelle Lantier, Joaquin Castilla, and Juan-MarÃa Torres corresponding author
Abstract
How susceptible pigs are to infection with sheep prions is unknown. We show, through transmission experiments in transgenic mice expressing porcine prion protein (PrP), that the susceptibility of this mouse model to bovine spongiform encephalopathy (BSE) can be enhanced after its passage in ARQ sheep, indicating that the pathogenicity of the BSE agent is modified after passage in sheep. Transgenic mice expressing porcine PrP were, nevertheless, completely resistant to infection with a broad panel of classical scrapie isolates from different sheep PrP genotypes and with different biochemical characteristics. The atypical (Nor98 like) isolate (SC-PS152) was the only scrapie isolate capable of transmission in these mice, although with a marked transmission barrier. Unexpectedly, the atypical scrapie agent appeared to undergo a strain phenotype shift upon transmission to porcine-PrP transgenic mice and acquired new strain properties, suggesting that atypical scrapie agent may exhibit different phenotypes depending on the host cellular PrP or other genetic factors.
snip...
Discussion In this study, transgenic mice expressing porcine PrP (8) were used to assess the transmission capacity of a wide range of TSE agents from sheep. Our results indicated that none of the classical scrapie isolates tested was transmitted to our porcine PrP mouse model after intracerebral inoculation (Table), suggesting a highly (if not completely) resistance to the classical scrapie strains tested independently of their origin and biochemical signature. The absence of successful transmission of the SC-PS48 isolates with an unglycosylated bands of 19 kDa-like BSE suggests a BSE-unrelated origin for these BSE-like scrapie strains.
The atypical isolate SC-PS152 was the only scrapie isolate able to infect the Po-PrP mouse model after intracerebral inoculation (Table), albeit with a low efficiency of infection in the first passage (attack rate 16%). These results suggest the potential ability of atypical scrapie prions to infect pigs, although with a strong transmission barrier. Given the increasing number of atypical scrapie cases found in Europe and in North America, the potential ability of atypical scrapie to adapt to the pig becoming more easily transmitted could raise concerns about the potential danger of feeding ruminant meat and bone meal to swine.
In our transmission experiments, an obviously shorter survival period (458 ± 11 dpi) and an increased attack rate (100%) were observed in PoPrP-Tg001 mice inoculated with sheep BSE (Table) compared with those inoculated with the original cattle BSE (>650 dpi, 19%). These last figures correlate well with those reported for other cattle BSE isolates (Table). Differences in survival times were maintained after subsequent passages in this mouse model (Table), suggesting that the increased infectivity of sheep BSE cannot be linked to a higher infectious titer in the initial inoculum but must be the outcome of a modification in the pathogenicity of the agent. We can also rule out that the primary amino acid sequence of the ovine PrPSC leads to more efficient conversion of porcine PrPC because scrapie isolates from sheep with the same ARQ-PrP genotype were not able to infect these mice (Table). Taken together, the increased infectivity of sheep BSE in the porcine PrP mouse model must be considered as increased pathogenicity of the agent attributable to its passage in sheep. These features support previous results indicating that the BSE agent modifies its biological properties after passage in sheep, with the result that its pathogenicity increases in transgenic mice expressing bovine PrP (24). An increased pathogenicity of ovine BSE was also reported in conventional RIII mice when compared with retrospective cattle BSE experiments (36). In other prion strains, passage through an intermediate species has also been noted to alter host susceptibility (37).
The enhanced infectivity of the BSE agent after its passage in ARQ sheep raises concern about its potential danger for other species, including humans. This question, as well as others related to the infectivity of the new porcine prion generated in this study, is currently being addressed in transmission experiments using transgenic mice expressing human PrP.
Upon passages in porcine PrP transgenic mice, the BSE agent retained most of its biochemical properties, except for its PrPres glycoprofile in which some differences were appreciable. Our comparative analysis of cattle BSE and sheep BSE upon transmission in porcine PrP transgenic mice showed that both agents exhibit similar molecular (Figure 2) and neuropathologic properties (Figure 4). These features were preserved after subsequent passages. These results suggest that, despite their modified pathogenicity, the 2 porcine prions generated share the same biochemical and neuropathologic properties, regardless of whether the BSE agent used to inoculate the mice was obtained from ARQ sheep or cows. In agreement with these results, the increased infectivity of sheep BSE previously observed upon transmission in bovine PrP transgenic mice was not reflected in its molecular or neuropathologic properties (24).
The atypical scrapie (SC-PS152) agent appeared to undergo a strain phenotype shift upon transmission to porcine PrP transgenic mice. Surprisingly, this novel strain phenotype was similar to that of sheep BSE propagated in the same mice in terms of several features: 1) survival times observed after stabilization in PoPrP-Tg001 mice (second passages) were similar (Table); 2) PrPres molecular profiles of the 2 agents in porcine PrP mice were indistinguishable (Figure 3); and 3) vacuolation profiles observed in second passages largely overlapped (Figure 4).
These findings could reflect the evolutionary potential of prion agents upon transmission to a foreign host able to promote strain shift and emergence of new properties (38,39). The converging molecular, neuropathologic, and biological properties of atypical scrapie and sheep BSE upon propagation in porcine transgenic mice could be the consequence of a restriction imposed by the porcine PrPC, which might only admit a few options as it changes its conformation to PrPSC.
Our results could also suggest a common origin for sheep BSE and atypical scrapie agents, which may exhibit different phenotypes depending on the host PrPC or other host factors. Although this last explanation seems to be less likely, so far we cannot draw any definitive conclusion on this issue. Whichever the case, the ability of an atypical scrapie to infect other species and its potential capacity to undergo a strain phenotype shift in the new host prompts new concerns about the possible spread of this uncommon TSE in other species as a masked prion undistinguishable from other strains.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2815954/
Transmission of the atypical/Nor98 scrapie agent to Suffolk sheep with VRQ/ARQ, ARQ/ARQ, and ARQ/ARR genotypes
Eric D. Cassmann,Najiba Mammadova,S. Jo Moore,Sylvie Benestad,Justin J. Greenlee Published: February 11, 2021
https://doi.org/10.1371/journal.pone.0246503
Abstract
Scrapie is a transmissible spongiform encephalopathy that occurs in sheep. Atypical/Nor98 scrapie occurs in sheep that tend to be resistant to classical scrapie and it is thought to occur spontaneously. The purpose of this study was to test the transmission of the Atypical/Nor98 scrapie agent in three genotypes of Suffolk sheep and characterize the distribution of misfolded prion protein (PrPSc). Ten sheep were intracranially inoculated with brain homogenate from a sheep with Atypical/Nor98 scrapie. All sheep with the ARQ/ARQ and ARQ/ARR genotypes developed Atypical/Nor98 scrapie confirmed by immunohistochemistry, and one sheep with the VRQ/ARQ genotype had detectable PrPSc consistent with Atypical/Nor98 scrapie at the experimental endpoint of 8 years. Sheep with mild early accumulations of PrPSc in the cerebellum had concomitant retinal PrPSc. Accordingly, large amounts of retinal PrPSc were identified in clinically affected sheep and sheep with dense accumulations of PrPSc in the cerebellum.
SNIP...
Results and discussion All three genotypes of sheep, VRQ/ARQ, ARQ/ARQ, and ARQ/ARR, were susceptible to the AS agent after intracranial inoculation of donor brain homogenate. The diagnosis of AS was confirmed by enzyme immunoassay (EIA) and immunohistochemistry (IHC) with the latter being confirmative. Previous studies have demonstrated experimental transmission of AS to AHQ/AHQ [14, 15] and ARQ/ARQ [16] genotype sheep after intracerebral transmission. Another study showed a phenotypic shift from AS to CH1641-like classical scrapie in a sheep with the AHQ/AHQ genotype [18]. In this study, sheep with the ARQ/ARR genotype had the shortest incubation period ranging from 4.9years to the experimental endpoint of 8 years (Table 1), and the attack rate was 100% (5/5). Clinical signs were observed in all ARQ/ARR sheep except for a single wether that was culled early to help establish experimental endpoints. Three ARQ/ARR genotype sheep were euthanized due to clinical neurologic disease 4.9–6.7 years post-inoculation. Out of the three genotypes examined, only the ARQ/ARR genotype sheep developed clinical neurologic disease within the eight-year incubation period. In clinically neurologic sheep, we observed stiff legged and hypermetric ataxia (dysmetria), abnormal rear stance, generalized tremors, tremors of the lips, weight loss, and generalized malaise. The spectrum of clinical signs was comparable to other reports of experimental AS in sheep [14, 15]. Three ARQ/ARR genotype sheep (804, 927 and 948) with the most severe dysmetria also had the greatest amount of cerebellar PrPSc. Since dysmetria is typical of animals with cerebellar disease [20], the tendency to observe this as the most consistent and severe neurologic sign is likely related to the characteristic cerebellar accumulation of PrPSc in sheep with AS. The ARQ/ARQ genotype had a long incubation period and remained clinically asymptomatic, as also reported by Okada et al. [16].
SNIP...
This experiment demonstrated the transmission of atypical scrapie to three genotypes of sheep after intracranially inoculation, and it is the first study demonstrating experimental transmission to sheep with a VRQ/ARQ PRNP genotype. Additionally, atypical scrapie is further characterized by demonstrating early accumulation of PrPSc in the retina of experimentally inoculated sheep.
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0246503
Experimental Oral Transmission of Atypical Scrapie to Sheep
Marion M. Simmons, S. Jo Moore,1 Timm Konold, Lisa Thurston, Linda A. Terry, Leigh Thorne, Richard Lockey, Chris Vickery, Stephen A.C. Hawkins, Melanie J. Chaplin, and John Spiropoulos
To investigate the possibility of oral transmission of atypical scrapie in sheep and determine the distribution of infectivity in the animals’ peripheral tissues, we challenged neonatal lambs orally with atypical scrapie; they were then killed at 12 or 24 months. Screening test results were negative for disease-specifi c prion protein in all but 2 recipients; they had positive results for examination of brain, but negative for peripheral tissues. Infectivity of brain, distal ileum, and spleen from all animals was assessed in mouse bioassays; positive results were obtained from tissues that had negative results on screening. These fi ndings demonstrate that atypical scrapie can be transmitted orally and indicate that it has the potential for natural transmission and iatrogenic spread through animal feed. Detection of infectivity in tissues negative by current surveillance methods indicates that diagnostic sensitivity is suboptimal for atypical scrapie, and potentially infectious material may be able to pass into the human food chain.
SNIP...
Although all TSEs are transmissible after intracerebral challenge to a susceptible host, only some are infectious under natural conditions. Therefore, it was important from a pathogenesis and disease control perspective to establish whether or not oral transmission can be successful. However, the challenge model in this study exposed animals as neonates, when the esophageal groove is operational and the lambs are physiologically monogastric. Exposure of 3-month-old ruminating animals to similar amounts of positive brain by the oral route have so far not resulted in any clinical disease, with all animals still alive >1,500 days post challenge (M.M. Simmons, unpub. data), but most natural cases have been recorded in animals older than this, so these animals may still progress to disease in the next few years. Since this challenge study in older animals has no time-kill component, and no losses caused by unrelated disease have occurred, whether any of these sheep are in a preclinical phase of disease is unknown. Unfortunately, the absence of detectable PrPSc in lymphoreticular tissues of sheep with atypical scrapie precludes the use of biopsies to ascertain early infection in these animals.
Transmission may be more effi cient in newborn animals; the incubation periods of sheep orally infected with classical scrapie were signifi cantly shorter in sheep challenged at 14 days of age than those challenged at 6 months of age (31). If, however, oral transmission is only effective in such young animals, then fi eld exposure would most likely have to be through milk, which is known to be a highly effective route of transmission for classical scrapie (32). No data are currently available on the potential infectivity of milk from animals with atypical scrapie.
Successful oral transmission also raises questions regarding the pathogenesis of this form of disease. There must be passage of the infectious agent from the alimentary canal to the brain through one of several possible routes, most likely those that have been suggested and discussed in detail for other TSEs, for example, retrograde neuronal transportation either directly (33–35) or through lymphoid structures or hematogenously (36). Infectivity in the absence of readily demonstrable PrPSc has been reported (37–39), and although the mouse bioassay may detect evidence of disease in other tissues, these data may not be available for at least another 2 years. More protease-sensitive forms of PrPSc may be broken down more effi ciently within cells and thus do not accumulate in peripheral tissues (19), enabling atypical PrPSc to transit the digestive tract and disseminate through other systems in small amounts before accumulating detectably in the central nervous system.
Although we do not have epidemiologic evidence that supports the effi cient spread of disease in the fi eld, these data imply that disease is potentially transmissible under fi eld situations and that spread through animal feed may be possible if the current feed restrictions were to be relaxed.
Additionally, almost no data are available on the potential for atypical scrapie to transmit to other food animal species, certainly by the oral route. However, work with transgenic mice has demonstrated the potential susceptibility of pigs, with the disturbing fi nding that the biochemical properties of the resulting PrPSc have changed on transmission (40). The implications of this observation for subsequent transmission and host target range are currently unknown.
How reassuring is this absence of detectable PrPSc from a public health perspective? The bioassays performed in this study are not titrations, so the infectious load of the positive gut tissues cannot be quantified, although infectivity has been shown unequivocally. No experimental data are currently available on the zoonotic potential of atypical scrapie, either through experimental challenge of humanized mice or any meaningful epidemiologic correlation with human forms of TSE. However, the detection of infectivity in the distal ileum of animals as young as 12 months, in which all the tissues tested were negative for PrPSc by the currently available screening and confirmatory diagnostic tests, indicates that the diagnostic sensitivity of current surveillance methods is suboptimal for detecting atypical scrapie and that potentially infectious material may be able to pass into the human food chain undetected.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3321785/pdf/10-1654_finalR.pdf
New evidence on the zoonotic potential of atypical BSE and atypical scrapie prion strains
PLEASE NOTE;
2.3.2. New evidence on the zoonotic potential of atypical BSE and atypical scrapie prion strainsNo
Olivier Andreoletti, INRA Research Director, Institut National de la Recherche Agronomique (INRA) – École Nationale Vétérinaire de Toulouse (ENVT), invited speaker, presented the results of two recently published scientific articles of interest, of which he is co-author: ‘Radical Change in Zoonotic Abilities of Atypical BSE Prion Strains as Evidenced by Crossing of Sheep Species Barrier in Transgenic Mice’ (MarinMoreno et al., 2020) and ‘The emergence of classical BSE from atypical/Nor98 scrapie’ (Huor et al., 2019).
In the first experimental study, H-type and L-type BSE were inoculated into transgenic mice expressing all three genotypes of the human PRNP at codon 129 and into adapted into ARQ and VRQ transgenic sheep mice. The results showed the alterations of the capacities to cross the human barrier species (mouse model) and emergence of sporadic CJD agents in Hu PrP expressing mice: type 2 sCJD in homozygous TgVal129 VRQ-passaged L-BSE, and type 1 sCJD in homozygous TgVal 129 and TgMet129 VRQ-passaged H-BSE.
https://efsa.onlinelibrary.wiley.com/doi/epdf/10.2903/sp.efsa.2020.EN-1946
Previous work has shown that the Stetsonville, WI outbreak of TME could have been precipitated by feeding mink a downer cow with atypical BSE; therefore, it very well may have originated from a cow with L-BSE. The agent of TME appears to remain stable, and it has a high transmission efficiency after a sequence of interspecies transmission events. Although C-BSE is the archetypal foodborne TSE, our findings indicate that L-BSE and bTME have greater transmission efficiencies in bovinized mice. Previous work has demonstrated that L-BSE also is more virulent than C-BSE in mice expressing the human prion protein [46, 55]. Although the documented incidence of L-BSE is low, the propensity of L-BSE and the TME agent to cross species barriers support the continued monitoring for atypical BSE.
https://bmcvetres.biomedcentral.com/articles/10.1186/s12917-020-02611-0
***>This work supports the ideas that L-BSE is a possible source for TME in mink and that the practice of feeding cattle with neurologic disease to mink should be avoided. This information is important to farmers who raise cattle, sheep, or mink.<***
1985
Evidence That Transmissible Mink Encephalopathy Results from Feeding Infected Cattle Over the next 8-10 weeks, approximately 40% of all the adult mink on the farm died from TME.
snip...
The rancher was a ''dead stock'' feeder using mostly (>95%) downer or dead dairy cattle...
https://web.archive.org/web/20090506002258/http://www.bseinquiry.gov.uk/files/mb/m09/tab05.pdf
https://web.archive.org/web/20090506001031/http://www.bseinquiry.gov.uk/files/mb/m09a/tab01.pdf
https://web.archive.org/web/20090506024922/http://www.bseinquiry.gov.uk/files/yb/1987/06/10004001.pdf
57 The experiment which might have determined whether BSE and scrapie were caused by the same agent (ie, the feeding of natural scrapie to cattle) was never undertaken in the UK.
It was, however, performed in the USA in 1979, when it was shown that cattle inoculated with the scrapie agent endemic in the flock of Suffolk sheep at the United States Department of Agriculture in Mission, Texas, developed a TSE quite unlike BSE. 32
The findings of the initial transmission, though not of the clinical or neurohistological examination, were communicated in October 1988 to Dr Watson, Director of the CVL, following a visit by Dr Wrathall, one of the project leaders in the Pathology Department of the CVL, to the United States Department of Agriculture. 33
The results were not published at this point, since the attempted transmission to mice from the experimental cow brain had been inconclusive.
The results of the clinical and histological differences between scrapie-affected sheep and cattle were published in 1995.
Similar studies in which cattle were inoculated intracerebrally with scrapie inocula derived from a number of scrapie-affected sheep of different breeds and from different States, were carried out at the US National Animal Disease Centre. 34
The results, published in 1994, showed that this source of scrapie agent, though pathogenic for cattle, did not produce the same clinical signs of brain lesions characteristic of BSE..
32 Clark, W., Hourrigan, J. and Hadlow, W. (1995) Encephalopathy in Cattle Experimentally Infected with the Scrapie Agent, American Journal of Veterinary Research, 56, 606-12
33 YB88/10.00/1.1
http://web.archive.org/web/20040823105233/www.bseinquiry.gov.uk/files/yb/1988/10/00001001.pdf
Technical Abstract:
Prion strains may vary in their ability to transmit to humans and animals. Few experimental studies have been done to provide evidence of differences between U.S. strains of scrapie, which can be distinguished by incubation times in inbred mice, microscopic lesions, immunoreactivity to various antibodies, or molecular profile (electrophoretic mobility and glycoform ratio). Recent work on two U.S. isolates of sheep scrapie supports that at least two distinct strains exist based on differences in incubation time and genotype of sheep affected. One isolate (No. 13-7) inoculated intracerebrally caused scrapie in sheep AA at codon 136 (AA136) and QQ at codon 171 (QQ171) of the prion protein in an average of 19 months post-inoculation (PI) whereas a second isolate (No. x124) caused disease in less than 12 months after oral inoculation in AV136/QQ171 sheep. Striking differences were evident when further strain analysis was done in R111, VM, C57Bl6, and C57Bl6xVM (F1) mice. No. 13-7 did not induce disease in any mouse strain at any time post-inoculation (PI) nor were brain tissues positive by western blot (WB). Positive WB results were obtained from mice inoculated with isolate No. x124 starting at day 380 PI. Incubation times averaged 508, 559, 601, and 633 days PI for RIII, C57Bl6, VM, and F1 mice, respectively. Further passage will be required to characterize these scrapie strains in mice.
***>This work provides evidence that multiple scrapie strains exist in U.S. sheep.
http://www.ars.usda.gov/research/publications/publications.htm?seq_no_115=227516
One of these isolates (TR316211) behaved like the CH1641 isolate, with PrPres features in mice similar to those in the sheep brain. From two other isolates (O100 and O104), two distinct PrPres phenotypes were identified in mouse brains, with either high (h-type) or low (l-type) apparent molecular masses of unglycosylated PrPres, the latter being similar to that observed with CH1641, TR316211, or BSE. Both phenotypes could be found in variable proportions in the brains of the individual mice. In contrast with BSE, l-type PrPres from "CH1641-like" isolates showed lower levels of diglycosylated PrPres. From one of these cases (O104), a second passage in mice was performed for two mice with distinct PrPres profiles. This showed a partial selection of the l-type phenotype in mice infected with a mouse brain with predominant l-type PrPres, and it was accompanied by a significant increase in the proportions of the diglycosylated band. These results are discussed in relation to the diversity of scrapie and BSE strains.
http://jvi.asm.org/cgi/content/full/81/13/7230?view=long&pmid=17442721
Docket No. APHIS-2007-0127 Scrapie in Sheep and Goats Terry Singeltary Sr. Submission Docket No. APHIS-2007-0127 Scrapie in Sheep and Goats SUMMARY: We are reopening the comment period for our proposed rule that would revise completely the scrapie regulations, which concern the risk groups and categories established for individual animals and for flocks, the use of genetic testing as a means of assigning risk levels to animals, movement restrictions for animals found to be genetically less susceptible or resistant to scrapie, and recordkeeping requirements. This action will allow interested persons additional time to prepare and submit comments.DATES: The comment period for the proposed rule published on September 10, 2015 (80 FR 54660-54692) is reopened. We will consider all comments that we receive on or before December 9, 2015. ...
PLEASE NOTE;
2.3.2. New evidence on the zoonotic potential of atypical BSE and atypical scrapie prion strainsNo
Olivier Andreoletti, INRA Research Director, Institut National de la Recherche Agronomique (INRA) – École Nationale Vétérinaire de Toulouse (ENVT), invited speaker, presented the results of two recently published scientific articles of interest, of which he is co-author: ‘Radical Change in Zoonotic Abilities of Atypical BSE Prion Strains as Evidenced by Crossing of Sheep Species Barrier in Transgenic Mice’ (MarinMoreno et al., 2020) and ‘The emergence of classical BSE from atypical/Nor98 scrapie’ (Huor et al., 2019).
In the first experimental study, H-type and L-type BSE were inoculated into transgenic mice expressing all three genotypes of the human PRNP at codon 129 and into adapted into ARQ and VRQ transgenic sheep mice. The results showed the alterations of the capacities to cross the human barrier species (mouse model) and emergence of sporadic CJD agents in Hu PrP expressing mice: type 2 sCJD in homozygous TgVal129 VRQ-passaged L-BSE, and type 1 sCJD in homozygous TgVal 129 and TgMet129 VRQ-passaged H-BSE.
https://efsa.onlinelibrary.wiley.com/doi/epdf/10.2903/sp.efsa.2020.EN-1946
Previous work has shown that the Stetsonville, WI outbreak of TME could have been precipitated by feeding mink a downer cow with atypical BSE; therefore, it very well may have originated from a cow with L-BSE. The agent of TME appears to remain stable, and it has a high transmission efficiency after a sequence of interspecies transmission events. Although C-BSE is the archetypal foodborne TSE, our findings indicate that L-BSE and bTME have greater transmission efficiencies in bovinized mice. Previous work has demonstrated that L-BSE also is more virulent than C-BSE in mice expressing the human prion protein [46, 55]. Although the documented incidence of L-BSE is low, the propensity of L-BSE and the TME agent to cross species barriers support the continued monitoring for atypical BSE.
https://bmcvetres.biomedcentral.com/articles/10.1186/s12917-020-02611-0
***>This work supports the ideas that L-BSE is a possible source for TME in mink and that the practice of feeding cattle with neurologic disease to mink should be avoided. This information is important to farmers who raise cattle, sheep, or mink.<***
1985
Evidence That Transmissible Mink Encephalopathy Results from Feeding Infected Cattle Over the next 8-10 weeks, approximately 40% of all the adult mink on the farm died from TME.
snip...
The rancher was a ''dead stock'' feeder using mostly (>95%) downer or dead dairy cattle...
https://web.archive.org/web/20090506002258/http://www.bseinquiry.gov.uk/files/mb/m09/tab05.pdf
https://web.archive.org/web/20090506001031/http://www.bseinquiry.gov.uk/files/mb/m09a/tab01.pdf
https://web.archive.org/web/20090506024922/http://www.bseinquiry.gov.uk/files/yb/1987/06/10004001.pdf
57 The experiment which might have determined whether BSE and scrapie were caused by the same agent (ie, the feeding of natural scrapie to cattle) was never undertaken in the UK.
It was, however, performed in the USA in 1979, when it was shown that cattle inoculated with the scrapie agent endemic in the flock of Suffolk sheep at the United States Department of Agriculture in Mission, Texas, developed a TSE quite unlike BSE. 32
The findings of the initial transmission, though not of the clinical or neurohistological examination, were communicated in October 1988 to Dr Watson, Director of the CVL, following a visit by Dr Wrathall, one of the project leaders in the Pathology Department of the CVL, to the United States Department of Agriculture. 33
The results were not published at this point, since the attempted transmission to mice from the experimental cow brain had been inconclusive.
The results of the clinical and histological differences between scrapie-affected sheep and cattle were published in 1995.
Similar studies in which cattle were inoculated intracerebrally with scrapie inocula derived from a number of scrapie-affected sheep of different breeds and from different States, were carried out at the US National Animal Disease Centre. 34
The results, published in 1994, showed that this source of scrapie agent, though pathogenic for cattle, did not produce the same clinical signs of brain lesions characteristic of BSE..
32 Clark, W., Hourrigan, J. and Hadlow, W. (1995) Encephalopathy in Cattle Experimentally Infected with the Scrapie Agent, American Journal of Veterinary Research, 56, 606-12
33 YB88/10.00/1.1
http://web.archive.org/web/20040823105233/www.bseinquiry.gov.uk/files/yb/1988/10/00001001.pdf
Technical Abstract:
Prion strains may vary in their ability to transmit to humans and animals. Few experimental studies have been done to provide evidence of differences between U.S. strains of scrapie, which can be distinguished by incubation times in inbred mice, microscopic lesions, immunoreactivity to various antibodies, or molecular profile (electrophoretic mobility and glycoform ratio). Recent work on two U.S. isolates of sheep scrapie supports that at least two distinct strains exist based on differences in incubation time and genotype of sheep affected. One isolate (No. 13-7) inoculated intracerebrally caused scrapie in sheep AA at codon 136 (AA136) and QQ at codon 171 (QQ171) of the prion protein in an average of 19 months post-inoculation (PI) whereas a second isolate (No. x124) caused disease in less than 12 months after oral inoculation in AV136/QQ171 sheep. Striking differences were evident when further strain analysis was done in R111, VM, C57Bl6, and C57Bl6xVM (F1) mice. No. 13-7 did not induce disease in any mouse strain at any time post-inoculation (PI) nor were brain tissues positive by western blot (WB). Positive WB results were obtained from mice inoculated with isolate No. x124 starting at day 380 PI. Incubation times averaged 508, 559, 601, and 633 days PI for RIII, C57Bl6, VM, and F1 mice, respectively. Further passage will be required to characterize these scrapie strains in mice.
***>This work provides evidence that multiple scrapie strains exist in U.S. sheep.
http://www.ars.usda.gov/research/publications/publications.htm?seq_no_115=227516
One of these isolates (TR316211) behaved like the CH1641 isolate, with PrPres features in mice similar to those in the sheep brain. From two other isolates (O100 and O104), two distinct PrPres phenotypes were identified in mouse brains, with either high (h-type) or low (l-type) apparent molecular masses of unglycosylated PrPres, the latter being similar to that observed with CH1641, TR316211, or BSE. Both phenotypes could be found in variable proportions in the brains of the individual mice. In contrast with BSE, l-type PrPres from "CH1641-like" isolates showed lower levels of diglycosylated PrPres. From one of these cases (O104), a second passage in mice was performed for two mice with distinct PrPres profiles. This showed a partial selection of the l-type phenotype in mice infected with a mouse brain with predominant l-type PrPres, and it was accompanied by a significant increase in the proportions of the diglycosylated band. These results are discussed in relation to the diversity of scrapie and BSE strains.
http://jvi.asm.org/cgi/content/full/81/13/7230?view=long&pmid=17442721
Docket No. APHIS-2007-0127 Scrapie in Sheep and Goats Terry Singeltary Sr. Submission Docket No. APHIS-2007-0127 Scrapie in Sheep and Goats SUMMARY: We are reopening the comment period for our proposed rule that would revise completely the scrapie regulations, which concern the risk groups and categories established for individual animals and for flocks, the use of genetic testing as a means of assigning risk levels to animals, movement restrictions for animals found to be genetically less susceptible or resistant to scrapie, and recordkeeping requirements. This action will allow interested persons additional time to prepare and submit comments.DATES: The comment period for the proposed rule published on September 10, 2015 (80 FR 54660-54692) is reopened. We will consider all comments that we receive on or before December 9, 2015. ...
Scrapie in Sheep and Goats Animal and Plant Health Inspection Service on Sep 10, 2015 Singeltary, Detwiler et al
Scrapie in Sheep and Goats Animal and Plant Health Inspection Service on Sep 10, 2015
Scrapie in Sheep and Goats Posted by the Animal and Plant Health Inspection Service on Sep 10, 2015
https://www.regulations.gov/document/APHIS-2007-0127-0001
PUBLIC SUBMISSION Comment from Terry Singeltary
Posted by the Animal and Plant Health Inspection Service on Nov 23, 2015
Docket Document (APHIS-2007-0127-0001) Comment Comment
Indeed, much science has changed about the Scrapie TSE prion, including more science linking Scrapie to humans. sadly, politics, industry, and trade, have not changed, and those usually trump sound science, as is the case with all Transmissible Spongiform Encephalopathy TSE Prion disease in livestock producing animals and the OIE. we can look no further at the legal trading of the Scrapie TSE prion both typical and atypical of all strains, and CWD all stains. With as much science of old, and now more new science to back this up, Scrapie of all types i.e. atypical and typical, BSE all strains, and CWD all strains, should be regulated in trade as BSE TSE PRION. In fact, I urge APHIS et al and the OIE, and all trading partners to take heed to the latest science on the TSE prion disease, all of them, and seriously reconsider the blatant disregards for human and animal health, all in the name of trade, with the continued relaxing of TSE Prion trade regulations through the 'NEGLIGIBLE BSE RISK' PROGRAM, which was set up to fail in the first place. If the world does not go back to the 'BSE RISK ASSESSMENTS', enhance, and or change that assessment process to include all TSE prion disease, i.e. 'TSE RISK ASSESSMENT', if we do not do this and if we continue this farce with OIE and the USDA et al, and the 'NEGLIGIBLE BSE RISK' PROGRAM, we will never eradicate the TSE prion aka mad cow type disease, they will continue to mutate and spread among species of human and animal origin, and they will continue to kill. ...
please see ;
O.05: Transmission of prions to primates after extended silent incubation periods: Implications for BSE and scrapie risk assessment in human populations
Emmanuel Comoy, Jacqueline Mikol, Valerie Durand, Sophie Luccantoni, Evelyne Correia, Nathalie Lescoutra, Capucine Dehen, and Jean-Philippe Deslys Atomic Energy Commission; Fontenay-aux-Roses, France
Prion diseases (PD) are the unique neurodegenerative proteinopathies reputed to be transmissible under field conditions since decades. The transmission of Bovine Spongiform Encephalopathy (BSE) to humans evidenced that an animal PD might be zoonotic under appropriate conditions. Contrarily, in the absence of obvious (epidemiological or experimental) elements supporting a transmission or genetic predispositions, PD, like the other proteinopathies, are reputed to occur spontaneously (atpical animal prion strains, sporadic CJD summing 80% of human prion cases). Non-human primate models provided the first evidences supporting the transmissibiity of human prion strains and the zoonotic potential of BSE. Among them, cynomolgus macaques brought major information for BSE risk assessment for human health (Chen, 2014), according to their phylogenetic proximity to humans and extended lifetime. We used this model to assess the zoonotic potential of other animal PD from bovine, ovine and cervid origins even after very long silent incubation periods.
*** We recently observed the direct transmission of a natural classical scrapie isolate to macaque after a 10-year silent incubation period,
***with features similar to some reported for human cases of sporadic CJD, albeit requiring fourfold longe incubation than BSE. Scrapie, as recently evoked in humanized mice (Cassard, 2014),
***is the third potentially zoonotic PD (with BSE and L-type BSE),
***thus questioning the origin of human sporadic cases. We will present an updated panorama of our different transmission studies and discuss the implications of such extended incubation periods on risk assessment of animal PD for human health.
===============
***thus questioning the origin of human sporadic cases***
===============
https://prion2015.files.wordpress.com/2015/05/prion2015abstracts.pdf
***This information will have a scientific impact since it is the first study that demonstrates the transmission of scrapie to a non-human primate with a close genetic relationship to humans. This information is especially useful to regulatory officials and those involved with risk assessment of the potential transmission of animal prion diseases to humans.
***This observation strengthens the questioning of the harmlessness of scrapie to humans, at a time when protective measures for human and animal health are being dismantled and reduced as c-BSE is considered controlled and being eradicated. Our results underscore the importance of precautionary and protective measures and the necessity for long-term experimental transmission studies to assess the zoonotic potential of other animal prion strains.
http://www.ars.usda.gov/research/publications/publications.htm?SEQ_NO_115=313160
please see file attachment for full submission and recent science and my deep concerns on the TSE Prion disease...
Singeltary comments
“With as much science of old, and now more new science to back this up, Scrapie of all types i.e. atypical and typical, BSE all strains, and CWD all strains, should be regulated in trade as BSE TSE PRION.”
Linda Detwiler
December 9, 2015
Regulatory Analysis and Development USDA, APHIS, PPD Station 3A-03.8 4700 River Road Unit 118 Riverdale, MD 20737 Re: Docket No: APHIS-2007-0127
Dear Sir or Madame: As an owner of a purebred Suffolk flock which has been enrolled in the Scrapie Certification Program since 1992 and is currently Export Certified, I appreciate the opportunity to submit comments to this very important rule. I am also writing as someone who has spent most of my career working in the prion field.
As a producer who on occasion needs to introduce new genetics into my flock via the purchase of a ram, I am opposed to allowing the animals in flocks where a case of atypical (nonclassical) scrapie has been diagnosed to move without any type of monitoring. Atypical scrapie has been shown to be orally transmitted and has a peripheral distribution of infectivity despite the absence or PrPsc (Simmons et. al., 2011; Andreoletti personal communication 2015) There has been no research to definitively rule out horizontal transmission of atypical scrapie.
Definition of exposed animal – In the new definition of exposed animal, if a probable date of infection cannot be determined, a date 2 years before the birth of the oldest scrapie-positive animal will be used. I recommend specifying that this should be 2 years before the birth of the oldest positive animal born in that flock
I would suggest that any reference to genetic resistance and susceptibility to scrapie especially in the definitions should prominantly specify that the relationship between genotype and scrapie pertains to classical scrapie and not atypical.
Linda A. Detwiler, DVM
Belle-Terre Farms
“As a producer who on occasion needs to introduce new genetics into my flock via the purchase of a ram, I am opposed to allowing the animals in flocks where a case of atypical (nonclassical) scrapie has been diagnosed to move without any type of monitoring. Atypical scrapie has been shown to be orally transmitted and has a peripheral distribution of infectivity despite the absence or PrPsc (Simmons et. al., 2011; Andreoletti personal communication 2015) There has been no research to definitively rule out horizontal transmission of atypical scrapie.”
end
Linda Detwiler Comments
Monday, November 16, 2015
Docket No. APHIS-2007-0127 Scrapie in Sheep and Goats Terry Singeltary Sr. Submission
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Agency: Animal and Plant Health Inspection Service (APHIS) Document Type: Rulemaking Title: Scrapie in Sheep and Goats Document ID: APHIS-2007-0127-0001
CH1641
https://transmissiblespongiformencephalopathy.blogspot.com/2022/09/transmission-of-ch1641-in-cattle.html
https://scrapie-usa.blogspot.com/2021/04/
http://scrapie-usa.blogspot.com/2019/11/review-update-on-classical-and-atypical.html
https://transmissiblespongiformencephalopathy.blogspot.com/2012/01/selection-of-distinct-strain-phenotypes.html
IBNC Tauopathy or TSE Prion disease, it appears, no one is sure
Terry S. Singeltary Sr., 03 Jul 2015 at 16:53 GMT
PLOS ONE Journal
IBNC Tauopathy or TSE Prion disease, it appears, no one is sure
Terry S. Singeltary Sr., 03 Jul 2015 at 16:53 GMT
***however in 1 C-type challenged animal, Prion 2015 Poster Abstracts S67 PrPsc was not detected using rapid tests for BSE.
***Subsequent testing resulted in the detection of pathologic lesion in unusual brain location and PrPsc detection by PMCA only.
*** IBNC Tauopathy or TSE Prion disease, it appears, no one is sure ***
https://journals.plos.org/plosone/article/comment?id=10.1371/annotation/5adef4ac-a7e4-46a4-8806-c8533d5c862c
WEDNESDAY, DECEMBER 23, 2020
Idiopathic Brainstem Neuronal Chromatolysis IBNC BSE TSE Prion a Review 2020
https://bse-atypical.blogspot.com/2020/12/idiopathic-brainstem-neuronal.html
Scrapie Field Trial was developed at Mission, Texas, on 450 acres of pastureland, part of the former Moore Air Force
EPIDEMIOLOGY OF SCRAPIE IN THE UNITED STATES
Academic Preg
James Hourriganl, Albert Klingsporn2, Edited by » Peast W. W. Clark3, and M, de Camp4
United States Department of Agriculture, Animal and Plant Health Inspection Service, Veterinary Services
snip...
METHODS
A Scrapie Field Trial was developed at Mission, Texas, to provide additional information for the eradication program on the epidemiology of natural scrapie. The Mission Field Trial Station is located on 450 acres of pastureland, part of the former Moore Air Force Base, near Mission,
Texas. It was designed to bring previously exposed, and later also unexposed, sheep or goats to the Station and maintain and breed them under close observation for extended periods to determine which animals would develop scrapie and define more closely the natural spread and other epidemiological aspects of the disease.
The 547 previously exposed sheep brought to the Mission Station beginning in 1964 were of the Cheviot, Hampshire, Montadale, or Suffolk breeds. They were purchased as field outbreaks occurred, and represented 21 bloodlines in which scrapie had been diagnosed. Upon arrival at the Station, the sheep were maintained on pasture, with supplemental feeding as necessary. The station was divided into 2 areas:
snip...
RESULTS
Table 1 indicated that previously exposed sheep brought to the Station at various times and ages (1 to 89 months old) included 333 Suffolks at risk. Of these, 98 (29%) developed scrapie. This demonstrated the necessity to slaughter such sheep to prevent further Spread of the disease, These pre- viously exposed Suffolks were bred at the Station and produced 446 progeny at risk. Of these 153 (34%) developed scrapie.
Although the minimum and average ages when scnapied were similar for both groups, some of the previously exposed Suffolks brought to the Station developed scrapie when much older--ewes 60 to 142 months old and rams 67 to 102 months old. O£ the 153 Suffolks born at the Station, only 3 were more than 60 months of age (65, 66, and 69 months old).
This difference in age scrapied was attributed to the fact that the Suffolks born at the Station may have been sub- ject to a greater exposure from birth.
It was also observed that when both dam and progeny were scrapied, the progeny nearly always developed clinical disease at a younger age than their respective dam. Thirty- two dams were scrapied at an average of 60 months of age. Forty-six of their progeny developed the disease at an average of 38 months (range 25 to 53 months). Thirty-seven of the 46 progeny were younger than the dam (average 20 months younger, range 2 to 99 months younger). Two were scrapied at the same age as their dams, and 8 were older (average 5 months, range 1 to 13 months older).
++. Although the incidence of scrapie was considerably Greater in the progeny of scrapied compared to free dams, the progeny of either scrapied or free dams manifested scrapie at the typical age and irrespective of the age their respective dams were scrapied. The differences in ages that dams and progeny were scrapied was believed due to difference of exposure, particularly whether they were exposed at an early age,
Table 2 summarized the data on exposed Suffolks and was Prepared so as to show scrapie incidence in the progeny of dams and sires of known Scrapie status. The scrapie incidence in the progeny of Free X Free parents was 25%, progeny of scrapied Sires 39%, and scrapied dams 42%. When both sire and dam were scrapied, the scrapie incidence in 18 Progeny at risk was 78%.
When the scrapie status of the sire was ignored, scrapie incidence in th- progeny of free dams was 34% and in pre y of scrapied da as 62%. When the scrapie status of the dam was ignored, scrapie incidence in the progeny of free sires was 26% and in the progeny of scrapied sires was 452.
Although the scrapie incidence was nearly double in the progeny of scrapied compared to free dams, the latter con- tributed a greater number of scrapied progeny, 116, compared to only 51 cases which had scrapied dams. This was because free dams made a considerably heavier contribution to the progeny at risk4-342 compared to 82. It was felt that in farm flocks a similar situation could exist.
It was possible that free dams could have been mis- classified; however, this was unlikely to have been significant, unless "nonclinical or carrier" dams exist. In this Suffolk group, the ages of 100 free dams of scrapied progeny ranged from 25 to 160 (average 97) months. These free dams did not show clinical signs of scrapie,”and there were no histopathological lesions suggesting scrapie in those which died, If one cannot classify as free, ewes which have reached 97 months (average) and did not develop the disease, from a practical standpoint, it is not possible to classify sheep as free, at least on the basis of clinical signs and histology. The free dams of 50% of the scrapied progeny were more than 100 months of age, averaging 126 months.
Upon arrival at the Mission Station at 3 to 9 months of age, the 140 previously unexposed sheep and goats were placed in infected pastures and corrals and were subjected to con- tact with a succession of natural cases of scrapie in sheep, and eventually also in goats. These animals were bred only within their respective groups and were not crossbred to other breeds of sheep or those brought to the Station from infected flocks or their progeny. The male or female animals mixed freely with animals of their respective sex of the infected Flock and were similarly identified and subjected to similar flock management and diagnostic procedures.
Table 3 indicated that natural scrapie had occurred in 5 of the 140 previously unexposed sheep. One case each occurred in Rambouillet, Targhee, and Hampshire ewes at 88, 89, and 89 months of age and in % Suffolk ewes at 73 and 102 months of age, and 85, 82, 80, 64, and 93 months following initial natural exposure. This represented a natural situation involving lateral spread, under the circumstances involved, when sheep were not exposed when very young. Scrapie was not detected clinicaliy or histologically in any of the dairy or Angora goats brought to the Station. The disease occurred in an average of 27% of the progeny of previously unexposed sheep or goats born at the Station and included cases in progeny of all breeds of sheep or goats taken there, The incidence in the progeny ranged from 14% in Rambouillet sheep to 61% in dairy goats. ~
These data showed that scrapie spread laterally, by contact exposure, from scrapied te previously free animals, but at an apparently lower rate when exposure was first received at the age of 3 to 9 months. These animals were presumed to be susceptible to the disease, as their progeny developed scrapie at rates and ages similar (on the average) to the progeny, pf previously exposed Suffolk sheep born and reared in the same environment.
It was suggested that the progeny of previously unexposed animals developed scrapie at a much higher rate than their parents, and at a younger age, because they were subjected to exposure from birth. The data did not rule out the possibility that the animals born at the Station could have also received the virus from their dams "vertically" prior te, at, or following birth.
Table 4 summarized the scrapie incidence in #he progeny, born at the Station, of previously unexposed dairy goats.
The data were prepared so as to show scrapie incidence in the progeny of dams and sires of known scrapie status.
The 58% incidence in the progeny (24 at risk) of Free X Free parents was more than twice the 25% seen in the Suffolk group (Table 2). Scrapied sires did not increase the incidence in goat progeny (it was 44%); scrapied dams increased the incidence to 71%. When both sire and dam were scrapied the incidence was 89%, with only 9 goat progeny at risk.
When the scrapie status of the sire was ignored, the scrapie incidence in the progeny of free dams was 56% and in the progeny of scrapied dams it was 74%.
Free dams contributed 34 progeny at risk and scrapied dams 31 progeny.
When the scrapie status of the dam was ignored, scrapie incidence was 64% in the progeny of free sires and a similar 66% in the progeny of scrapied sires.
A total of 244 sheep (127 Suffolk, 59 Rambouillet, and 58 Targhee) were removed from scrapie exposure within a few hours of birth or at 4, 9, or 20 months of age and placed in isolation pens. Removal of sheep from exposure at these ages was selected as being representative of usual flock operations when sheep might be sold from an infected flock at weaning, the first fall or the second fall after their birth.
Table 5 reflected the fate of such animals. Four of the 6 scrapied sheep which had been isolated at birth were Suffolks and the 2 older animals were Targhees. The first case in the group isolated at birth was a Targhee, progeny of a ewe that did not develop clinical scrapie. The scrapie incidence in 36 at risk Suffolks removed from exposure at birth was 11%, con- siderably less -“en that expected had these animals remz d in an infected en ment.
Table 6 reflected the status of 51 goats isolated from scrapie exposure at birth, and at 6, 8 to 10, 20, 32 to 59 and 60 to 82 months of age.
None of the goats removed at birth developed scrapie, although all 5 of those alive at 5 years of age had scrapied dams and 1 also had a scrapied sire. The sire of the remaining 4 had sired 7 scrapied progeny. Under such circumstances, had they remained in an infected environment nearly all of these goats would have been expected to develop scrapie. With the exception of the 20 month group, scrapie occurred at an incidence of 25 to 100% in ali other groups and at the expected age. A further observation was that 4 of the progeny of these dairy goats, born and kept apart from any sheep, developed scrapie which suggested that goats were not "dead- end hosts" insofar as scrapie was concerned.
Table 7 recorded the fate of progeny of certain selected scrapied or free Suffolk sheep or dairy goat dams.’
Suffolk ewe G298 was scrapied at 46 months of age. She had twin lambs in 1969 and 1 lamb in 1970. All 3 lambs developed scrapie. Suffolk ewe G27a was scrapied at 39 months. Her lamb born in 1966 was scrapied at 53 months; however, her lambs born in 1967 and 1968 remained free--lived to 102 months of age.
Suffolk ewe G25a died at 131] months of age and was nega- tive clinically and histologically. Mice remained negative following intracerebral inoculation of brain, spleen, and lymph nodes from this ewe. This ewe had 9 progeny at risk, of which 4 developed scrapie and 5 did not. There was no dis- cernible pattern to the cases. In two instances, 1 twin was scrapied and 1 remained free.
Goat B259 was scrapied when 43 months old. All of her 6 progeny at risk developed scrapie.
Goat B14a remained free and died at 101 months of age. Of her 11 progeny at risk, 7 were scrapied and 4 were not.
It was observed at the Station that when scrapied dams had several progeny at risk, 1 or more progeny usually developed the disease. However, many such scrapied dams also had progeny which lived, or are living, considerably beyond the age of their dams and beyond the age animals born at the Station manifested the disease.
It was also observed that individual free dams had free progeny in earlier years followed by scrapied progeny when they were older, or had scrapied progeny when young followed by free progeny when older, or scrapie and free progeny dis- persed throughout the dam's breeding life. The same situation occurred in progeny of scrapied dams; however, the pattern was less irregular due to the smaller number of progeny from each scrapied dam and the higher incidence of scrapie in such progeny. Circumstances prevented breeding all ewes ary year and, thus, many had only 1 progeny at risk. Scrapie developed in 100% of the single progeny at risk of 11 scrapied and 15 free dams. The 26 scrapied progeny were equally divided between ewes and rams.
Table 8 reflected the difference in age scrapied of - sheep brought to the Station compared to the age scrapied of those born there. Although the average age of previously exposed sheep (Suffolks) brought to the Station did not differ greatly from the overall average, several animals brought to the Station developed the disease at quite advanced ages. The previously unexposed scrapied animals brought to the Station were also considerably older than animals born there. Progeny of scrapied dams developed the disease at a slightly younger age than did progeny of free dams. The average age was nearly the same for males and females.
DISCUSSION
snip...see full text;
http://web.archive.org/web/20030513212324/http://www.bseinquiry.gov.uk/files/mb/m08b/tab64.pdf
Scrapie Field Trial was developed at Mission, Texas, on 450 acres of pastureland, part of the former Moore Air Force Base
EPIDEMIOLOGY OF SCRAPIE IN THE UNITED STATES
http://web.archive.org/web/20030513212324/http://www.bseinquiry.gov.uk/files/mb/m08b/tab64.pdf
terry
Comment Tracking Number: xxxxxxxxxxxxxx
Your comment may be viewable on Regulations.govonce the agency has reviewed it. This process is dependent on agency public submission policies/procedures and processing times. Use your tracking number to find out the status of your comment.
Agency: Animal and Plant Health Inspection Service (APHIS) Document Type: Rulemaking Title: Scrapie in Sheep and Goats Document ID: APHIS-2007-0127-0001
CH1641
https://transmissiblespongiformencephalopathy.blogspot.com/2022/09/transmission-of-ch1641-in-cattle.html
https://scrapie-usa.blogspot.com/2021/04/
http://scrapie-usa.blogspot.com/2019/11/review-update-on-classical-and-atypical.html
https://transmissiblespongiformencephalopathy.blogspot.com/2012/01/selection-of-distinct-strain-phenotypes.html
IBNC Tauopathy or TSE Prion disease, it appears, no one is sure
Terry S. Singeltary Sr., 03 Jul 2015 at 16:53 GMT
PLOS ONE Journal
IBNC Tauopathy or TSE Prion disease, it appears, no one is sure
Terry S. Singeltary Sr., 03 Jul 2015 at 16:53 GMT
***however in 1 C-type challenged animal, Prion 2015 Poster Abstracts S67 PrPsc was not detected using rapid tests for BSE.
***Subsequent testing resulted in the detection of pathologic lesion in unusual brain location and PrPsc detection by PMCA only.
*** IBNC Tauopathy or TSE Prion disease, it appears, no one is sure ***
https://journals.plos.org/plosone/article/comment?id=10.1371/annotation/5adef4ac-a7e4-46a4-8806-c8533d5c862c
WEDNESDAY, DECEMBER 23, 2020
Idiopathic Brainstem Neuronal Chromatolysis IBNC BSE TSE Prion a Review 2020
https://bse-atypical.blogspot.com/2020/12/idiopathic-brainstem-neuronal.html
Scrapie Field Trial was developed at Mission, Texas, on 450 acres of pastureland, part of the former Moore Air Force
EPIDEMIOLOGY OF SCRAPIE IN THE UNITED STATES
Academic Preg
James Hourriganl, Albert Klingsporn2, Edited by » Peast W. W. Clark3, and M, de Camp4
United States Department of Agriculture, Animal and Plant Health Inspection Service, Veterinary Services
snip...
METHODS
A Scrapie Field Trial was developed at Mission, Texas, to provide additional information for the eradication program on the epidemiology of natural scrapie. The Mission Field Trial Station is located on 450 acres of pastureland, part of the former Moore Air Force Base, near Mission,
Texas. It was designed to bring previously exposed, and later also unexposed, sheep or goats to the Station and maintain and breed them under close observation for extended periods to determine which animals would develop scrapie and define more closely the natural spread and other epidemiological aspects of the disease.
The 547 previously exposed sheep brought to the Mission Station beginning in 1964 were of the Cheviot, Hampshire, Montadale, or Suffolk breeds. They were purchased as field outbreaks occurred, and represented 21 bloodlines in which scrapie had been diagnosed. Upon arrival at the Station, the sheep were maintained on pasture, with supplemental feeding as necessary. The station was divided into 2 areas:
snip...
RESULTS
Table 1 indicated that previously exposed sheep brought to the Station at various times and ages (1 to 89 months old) included 333 Suffolks at risk. Of these, 98 (29%) developed scrapie. This demonstrated the necessity to slaughter such sheep to prevent further Spread of the disease, These pre- viously exposed Suffolks were bred at the Station and produced 446 progeny at risk. Of these 153 (34%) developed scrapie.
Although the minimum and average ages when scnapied were similar for both groups, some of the previously exposed Suffolks brought to the Station developed scrapie when much older--ewes 60 to 142 months old and rams 67 to 102 months old. O£ the 153 Suffolks born at the Station, only 3 were more than 60 months of age (65, 66, and 69 months old).
This difference in age scrapied was attributed to the fact that the Suffolks born at the Station may have been sub- ject to a greater exposure from birth.
It was also observed that when both dam and progeny were scrapied, the progeny nearly always developed clinical disease at a younger age than their respective dam. Thirty- two dams were scrapied at an average of 60 months of age. Forty-six of their progeny developed the disease at an average of 38 months (range 25 to 53 months). Thirty-seven of the 46 progeny were younger than the dam (average 20 months younger, range 2 to 99 months younger). Two were scrapied at the same age as their dams, and 8 were older (average 5 months, range 1 to 13 months older).
++. Although the incidence of scrapie was considerably Greater in the progeny of scrapied compared to free dams, the progeny of either scrapied or free dams manifested scrapie at the typical age and irrespective of the age their respective dams were scrapied. The differences in ages that dams and progeny were scrapied was believed due to difference of exposure, particularly whether they were exposed at an early age,
Table 2 summarized the data on exposed Suffolks and was Prepared so as to show scrapie incidence in the progeny of dams and sires of known Scrapie status. The scrapie incidence in the progeny of Free X Free parents was 25%, progeny of scrapied Sires 39%, and scrapied dams 42%. When both sire and dam were scrapied, the scrapie incidence in 18 Progeny at risk was 78%.
When the scrapie status of the sire was ignored, scrapie incidence in th- progeny of free dams was 34% and in pre y of scrapied da as 62%. When the scrapie status of the dam was ignored, scrapie incidence in the progeny of free sires was 26% and in the progeny of scrapied sires was 452.
Although the scrapie incidence was nearly double in the progeny of scrapied compared to free dams, the latter con- tributed a greater number of scrapied progeny, 116, compared to only 51 cases which had scrapied dams. This was because free dams made a considerably heavier contribution to the progeny at risk4-342 compared to 82. It was felt that in farm flocks a similar situation could exist.
It was possible that free dams could have been mis- classified; however, this was unlikely to have been significant, unless "nonclinical or carrier" dams exist. In this Suffolk group, the ages of 100 free dams of scrapied progeny ranged from 25 to 160 (average 97) months. These free dams did not show clinical signs of scrapie,”and there were no histopathological lesions suggesting scrapie in those which died, If one cannot classify as free, ewes which have reached 97 months (average) and did not develop the disease, from a practical standpoint, it is not possible to classify sheep as free, at least on the basis of clinical signs and histology. The free dams of 50% of the scrapied progeny were more than 100 months of age, averaging 126 months.
Upon arrival at the Mission Station at 3 to 9 months of age, the 140 previously unexposed sheep and goats were placed in infected pastures and corrals and were subjected to con- tact with a succession of natural cases of scrapie in sheep, and eventually also in goats. These animals were bred only within their respective groups and were not crossbred to other breeds of sheep or those brought to the Station from infected flocks or their progeny. The male or female animals mixed freely with animals of their respective sex of the infected Flock and were similarly identified and subjected to similar flock management and diagnostic procedures.
Table 3 indicated that natural scrapie had occurred in 5 of the 140 previously unexposed sheep. One case each occurred in Rambouillet, Targhee, and Hampshire ewes at 88, 89, and 89 months of age and in % Suffolk ewes at 73 and 102 months of age, and 85, 82, 80, 64, and 93 months following initial natural exposure. This represented a natural situation involving lateral spread, under the circumstances involved, when sheep were not exposed when very young. Scrapie was not detected clinicaliy or histologically in any of the dairy or Angora goats brought to the Station. The disease occurred in an average of 27% of the progeny of previously unexposed sheep or goats born at the Station and included cases in progeny of all breeds of sheep or goats taken there, The incidence in the progeny ranged from 14% in Rambouillet sheep to 61% in dairy goats. ~
These data showed that scrapie spread laterally, by contact exposure, from scrapied te previously free animals, but at an apparently lower rate when exposure was first received at the age of 3 to 9 months. These animals were presumed to be susceptible to the disease, as their progeny developed scrapie at rates and ages similar (on the average) to the progeny, pf previously exposed Suffolk sheep born and reared in the same environment.
It was suggested that the progeny of previously unexposed animals developed scrapie at a much higher rate than their parents, and at a younger age, because they were subjected to exposure from birth. The data did not rule out the possibility that the animals born at the Station could have also received the virus from their dams "vertically" prior te, at, or following birth.
Table 4 summarized the scrapie incidence in #he progeny, born at the Station, of previously unexposed dairy goats.
The data were prepared so as to show scrapie incidence in the progeny of dams and sires of known scrapie status.
The 58% incidence in the progeny (24 at risk) of Free X Free parents was more than twice the 25% seen in the Suffolk group (Table 2). Scrapied sires did not increase the incidence in goat progeny (it was 44%); scrapied dams increased the incidence to 71%. When both sire and dam were scrapied the incidence was 89%, with only 9 goat progeny at risk.
When the scrapie status of the sire was ignored, the scrapie incidence in the progeny of free dams was 56% and in the progeny of scrapied dams it was 74%.
Free dams contributed 34 progeny at risk and scrapied dams 31 progeny.
When the scrapie status of the dam was ignored, scrapie incidence was 64% in the progeny of free sires and a similar 66% in the progeny of scrapied sires.
A total of 244 sheep (127 Suffolk, 59 Rambouillet, and 58 Targhee) were removed from scrapie exposure within a few hours of birth or at 4, 9, or 20 months of age and placed in isolation pens. Removal of sheep from exposure at these ages was selected as being representative of usual flock operations when sheep might be sold from an infected flock at weaning, the first fall or the second fall after their birth.
Table 5 reflected the fate of such animals. Four of the 6 scrapied sheep which had been isolated at birth were Suffolks and the 2 older animals were Targhees. The first case in the group isolated at birth was a Targhee, progeny of a ewe that did not develop clinical scrapie. The scrapie incidence in 36 at risk Suffolks removed from exposure at birth was 11%, con- siderably less -“en that expected had these animals remz d in an infected en ment.
Table 6 reflected the status of 51 goats isolated from scrapie exposure at birth, and at 6, 8 to 10, 20, 32 to 59 and 60 to 82 months of age.
None of the goats removed at birth developed scrapie, although all 5 of those alive at 5 years of age had scrapied dams and 1 also had a scrapied sire. The sire of the remaining 4 had sired 7 scrapied progeny. Under such circumstances, had they remained in an infected environment nearly all of these goats would have been expected to develop scrapie. With the exception of the 20 month group, scrapie occurred at an incidence of 25 to 100% in ali other groups and at the expected age. A further observation was that 4 of the progeny of these dairy goats, born and kept apart from any sheep, developed scrapie which suggested that goats were not "dead- end hosts" insofar as scrapie was concerned.
Table 7 recorded the fate of progeny of certain selected scrapied or free Suffolk sheep or dairy goat dams.’
Suffolk ewe G298 was scrapied at 46 months of age. She had twin lambs in 1969 and 1 lamb in 1970. All 3 lambs developed scrapie. Suffolk ewe G27a was scrapied at 39 months. Her lamb born in 1966 was scrapied at 53 months; however, her lambs born in 1967 and 1968 remained free--lived to 102 months of age.
Suffolk ewe G25a died at 131] months of age and was nega- tive clinically and histologically. Mice remained negative following intracerebral inoculation of brain, spleen, and lymph nodes from this ewe. This ewe had 9 progeny at risk, of which 4 developed scrapie and 5 did not. There was no dis- cernible pattern to the cases. In two instances, 1 twin was scrapied and 1 remained free.
Goat B259 was scrapied when 43 months old. All of her 6 progeny at risk developed scrapie.
Goat B14a remained free and died at 101 months of age. Of her 11 progeny at risk, 7 were scrapied and 4 were not.
It was observed at the Station that when scrapied dams had several progeny at risk, 1 or more progeny usually developed the disease. However, many such scrapied dams also had progeny which lived, or are living, considerably beyond the age of their dams and beyond the age animals born at the Station manifested the disease.
It was also observed that individual free dams had free progeny in earlier years followed by scrapied progeny when they were older, or had scrapied progeny when young followed by free progeny when older, or scrapie and free progeny dis- persed throughout the dam's breeding life. The same situation occurred in progeny of scrapied dams; however, the pattern was less irregular due to the smaller number of progeny from each scrapied dam and the higher incidence of scrapie in such progeny. Circumstances prevented breeding all ewes ary year and, thus, many had only 1 progeny at risk. Scrapie developed in 100% of the single progeny at risk of 11 scrapied and 15 free dams. The 26 scrapied progeny were equally divided between ewes and rams.
Table 8 reflected the difference in age scrapied of - sheep brought to the Station compared to the age scrapied of those born there. Although the average age of previously exposed sheep (Suffolks) brought to the Station did not differ greatly from the overall average, several animals brought to the Station developed the disease at quite advanced ages. The previously unexposed scrapied animals brought to the Station were also considerably older than animals born there. Progeny of scrapied dams developed the disease at a slightly younger age than did progeny of free dams. The average age was nearly the same for males and females.
DISCUSSION
snip...see full text;
http://web.archive.org/web/20030513212324/http://www.bseinquiry.gov.uk/files/mb/m08b/tab64.pdf
Scrapie Field Trial was developed at Mission, Texas, on 450 acres of pastureland, part of the former Moore Air Force Base
EPIDEMIOLOGY OF SCRAPIE IN THE UNITED STATES
http://web.archive.org/web/20030513212324/http://www.bseinquiry.gov.uk/files/mb/m08b/tab64.pdf
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