Research Project: Elucidating the Pathobiology and Transmission of Transmissible Spongiform Encephalopathies
Location: Virus and Prion Research
2023 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
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, to develop a unified protocol for the detection of CWD prions byreal-time quaking induced conversion (RT-QuIC) that utilizes an enrichment step that is capable of detection of disease in antemortem samples. This protocol has been distributed to diagnostic laboratories for evaluation. We have also made significant progress on novel sampling procedures for detection of transmissible spongiform encephalopathies (TSEs) utilizing rectal brush sampling that does not require in depth training or knowledge of anatomy. We have also developed protocols for amplification-based TSE diagnosis using alternate choices of amyloid binding fluorescent dye.
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 and observation of the animals is ongoing.
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 (two years at this point) due to insufficient animal space.
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 have begun, but not completed the acquisition of these samples. In summary, the goals of the project plan for FY22 consisted of 11 milestones, ten of which were either fully or substantially met. The one milestone in this plan that was not met was due to insufficient animal availability and space constraints and will be initiated when those have been resolved.
Accomplishments
1. Sheep scrapie agent can infect white-tailed deer after oronasal exposure. The origin of chronic wasting disease (CWD) is not known, but it has many similarities to the prion disease of sheep called scrapie. It has long been hypothesized that CWD could have arisen through transmission of sheep scrapie to deer. ARS researches in Ames, Iowa, conducted a study 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.
2. A novel sampling method was developed for monitoring CWD in farmed cervids to help maintain a CWD free environment. While the transmissible spongiform encephalopathies (TSEs) scrapie and bovine spongiform encephalopathy (BSE) have been largely controlled through selective breeding and a ruminant feed ban respectively, neither approach is applicable to chronic wasting disease (CWD). At this point the only method for protecting farmed cervids is maintenance of a CWD free environment. To accomplish this highly sensitive antemortem diagnostic methods using a non-invasive sampling protocol are needed to ensure that animals leaving or being introduced to new herds are free of CWD. ARS researchers in Ames, Iowa, developed a method using a rectal brush procedure for sampling coupled with the highly sensitive test known as real time quaking induced conversion (RT-QuIC). The rectal brush eliminates the need for trained personnel in the sample collection and allows for repeat sampling without reduction of available lymphoid tissue as might occur for rectal biopsy. This method will assist in the monitoring of CWD status aiding producers in preventing the introduction of CWD into their herd.
Review Publications
Cassmann, E.D., Brown, Q.L., Frese, A.J., Lambert, Z.J., West Greenlee, H.M., Greenlee, J.J. 2022. Effect of inoculation with prion dilutions within the dynamic range of ELISA absorbance on prion incubation period. Veterinary Research Communications. 46(4):1377-1380. https://doi.org/10.1007/s11259-022-10013-w.
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.
Silva, C.J., Cassmann, E.D., Greenlee, J.J., Erickson-Beltran, M.L., Requena, J.R. 2023. A mass spectrometry-based method of quantifying the contribution of the lysine polymorphism at position 171 in sheep PrP. Journal of American Society for Mass Spectrometry. 34(2):245-254. https://doi.org/10.1021/jasms.2c00277.
Harm, T.A., Smith, J.D., Cassmann, E.D., Greenlee, J.J. 2022. Combinatorial treatment of brain samples from sheep with scrapie using sodium percarbonate, sodium dodecyl sulfate, and proteinase K increases survival time in inoculated susceptible sheep. Research in Veterinary Science. 152:497-503. https://doi.org/10.1016/j.rvsc.2022.09.002.
Last Modified: 03/24/2024
''1. Sheep scrapie agent can infect white-tailed deer after oronasal exposure. The origin of chronic wasting disease (CWD) is not known, but it has many similarities to the prion disease of sheep called scrapie. It has long been hypothesized that CWD could have arisen through transmission of sheep scrapie to deer. ARS researches in Ames, Iowa, conducted a study 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.''
COLORADO THE ORIGIN OF CHRONIC WASTING DISEASE CWD TSE PRION?
*** Spraker suggested an interesting explanation for the occurrence of CWD. The deer pens at the Foot Hills Campus were built some 30-40 years ago by a Dr. Bob Davis. At or abut that time, allegedly, some scrapie work was conducted at this site. When deer were introduced to the pens they occupied ground that had previously been occupied by sheep.
IN CONFIDENCE, REPORT OF AN UNCONVENTIONAL SLOW VIRUS DISEASE IN ANIMALS IN THE USA 1989
***> CWD TO PIGS <***
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
Author item Moore, Sarah item Kunkle, Robert item Kondru, Naveen item Manne, Sireesha item Smith, Jodi item Kanthasamy, Anumantha item West Greenlee, M item Greenlee, Justin
Submitted to: Prion Publication Type: Abstract Only Publication Acceptance Date: 3/15/2017 Publication Date: N/A Citation: N/A Interpretive Summary:
Technical Abstract: Aims: Chronic wasting disease (CWD) is a naturally-occurring, fatal neurodegenerative disease of cervids. We previously demonstrated that disease-associated prion protein (PrPSc) can be detected in the brain and retina from pigs challenged intracranially or orally with the CWD agent. In that study, neurological signs consistent with prion disease were observed only in one pig: an intracranially challenged pig that was euthanized at 64 months post-challenge. The purpose of this study was to use an antigen-capture immunoassay (EIA) and real-time quaking-induced conversion (QuIC) to determine whether PrPSc is present in lymphoid tissues from pigs challenged with the CWD agent.
Methods: At two months of age, crossbred pigs were challenged by the intracranial route (n=20), oral route (n=19), or were left unchallenged (n=9). At approximately 6 months of age, the time at which commercial pigs reach market weight, half of the pigs in each group were culled (<6 month challenge groups). The remaining pigs (>6 month challenge groups) were allowed to incubate for up to 73 months post challenge (mpc). The retropharyngeal lymph node (RPLN) was screened for the presence of PrPSc by EIA and immunohistochemistry (IHC). The RPLN, palatine tonsil, and mesenteric lymph node (MLN) from 6-7 pigs per challenge group were also tested using EIA and QuIC.
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.
CONFIDENTIAL
EXPERIMENTAL PORCINE SPONGIFORM ENCEPHALOPATHY
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. ...
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.
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.....
snip...see much more here ;
WEDNESDAY, APRIL 05, 2017
Disease-associated prion protein detected in lymphoid tissues from pigs challenged with the agent of chronic wasting disease
WEDNESDAY, APRIL 05, 2017
*** Disease-associated prion protein detected in lymphoid tissues from pigs challenged with the agent of chronic wasting disease ***
***> CWD TO CATTLE
Transmission of the chronic wasting disease agent from elk to cattle after oronasal exposure
Justin Greenlee, Jifeng Bian, Zoe Lambert, Alexis Frese, and Eric Cassmann Virus and Prion Research Unit, National Animal Disease Center, USDA-ARS, Ames, IA, USA
Aims: The purpose of this study was to determine the susceptibility of cattle to chronic wasting disease agent from elk.
Conclusions: Cattle with the E211K polymorphism are susceptible to the CWD agent after oronasal exposure of 0.2 g of infectious material.
"Cattle with the E211K polymorphism are susceptible to the CWD agent after oronasal exposure of 0.2 g of infectious material."
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Strain characterization of chronic wasting disease in bovine-PrP transgenic mice
Conclusions: Altogether, these results exhibit the diversity of CWD strains present in the panel of CWD isolates and the ability of at least some CWD isolates to infect bovine species. Cattle being one of the most important farming species, this ability represents a potential threat to both animal and human health, and consequently deserves further study.
"Altogether, these results exhibit the diversity of CWD strains present in the panel of CWD isolates and the ability of at least some CWD isolates to infect bovine species. Cattle being one of the most important farming species, this ability represents a potential threat to both animal and human health, and consequently deserves further study."
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Comparing the Distribution of Ovine Classical Scrapie and Sporadic Creutzfeldt-Jakob Disease in Italy: Spatial and Temporal Associations (2002-2014)
Aim: This study aims to investigate potential spatial and temporal associations between Creutzfeldt-Jakob disease (CJD) in humans (2010-2014) and ovine classical scrapie (CS) (2002- 2006) in Italy, serving as a proxy for exposure.
Results: The analysis of data at the district level revealed no significant association. However, when considering aggregated regional data, all four models consistently indicated a statistically significant positive association, suggesting a higher incidence of the disease in humans as the regional incidence of sheep scrapie increased.
Conclusions: While the results are intriguing, it is important to acknowledge the inherent limitations of ecological studies. Nevertheless, these findings provide valuable evidence to formulate a hypothesis regarding the zoonotic potential of classical scrapie. Further investigations are necessary, employing specific designs such as analytical epidemiology studies, to test this hypothesis effectively.
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Transmission of Idiopathic human prion disease CJD MM1 to small ruminant mouse models (Tg338 and Tg501).
Results: No evidence of transmission was found on a first passage in Tg338 nor Tg501ovinized mice, but on second passage, 4/10 Tg338 mice succumbed to CJDMM1 (40% attack rate after 645 dpi) and 1/12 Tg501 mice (519dpi, 10 still alive). The remaining 2nd passages are still ongoing. Conclusions: In this poster, the neuropathological features of the resulting strain are discussed.
Transmission of scrapie prions to primate after an extended silent incubation period
*** In complement to the recent demonstration that humanized mice are susceptible to scrapie, we report here the first observation of direct transmission of a natural classical scrapie isolate to a macaque after a 10-year incubation period. Neuropathologic examination revealed all of the features of a prion disease: spongiform change, neuronal loss, and accumulation of PrPres throughout the CNS.
*** 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.
***Transmission data also revealed that several scrapie prions propagate in HuPrP-Tg mice with efficiency comparable to that of cattle BSE. While the efficiency of transmission at primary passage was low, subsequent passages resulted in a highly virulent prion disease in both Met129 and Val129 mice.
***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.
***Moreover, sporadic disease has never been observed in breeding colonies or primate research laboratories, most notably among hundreds of animals over several decades of study at the National Institutes of Health25, and in nearly twenty older animals continuously housed in our own facility.***
Even if the prevailing view is that sporadic CJD is due to the spontaneous formation of CJD prions, it remains possible that its apparent sporadic nature may, at least in part, result from our limited capacity to identify an environmental origin.
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.
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PRION 2015 CONFERENCE
PRION 2016 TOKYO
Saturday, April 23, 2016
SCRAPIE WS-01: Prion diseases in animals and zoonotic potential 2016
Prion. 10:S15-S21. 2016 ISSN: 1933-6896 1933-690X
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.
Title: Transmission of scrapie prions to primate after an extended silent incubation period)
*** In complement to the recent demonstration that humanized mice are susceptible to scrapie, we report here the first observation of direct transmission of a natural classical scrapie isolate to a macaque after a 10-year incubation period. Neuropathologic examination revealed all of the features of a prion disease: spongiform change, neuronal loss, and accumulation of PrPres throughout the CNS.
*** 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.
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 Marín-Moreno & Juan María 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 Marín-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.
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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)
PLoS Pathog. 2023 Dec; 19(12): e1011815.
Published online 2023 Dec 4. doi: 10.1371/journal.ppat.1011815
PMCID: PMC10721168
PMID: 38048370
Disease phenotype of classical sheep scrapie is changed upon experimental passage through white-tailed deer
Robyn D. Kokemuller, Formal analysis, Investigation, Writing – original draft, Writing – review & editing, 1 S. Jo Moore, Formal analysis, Investigation, Writing – original draft, Writing – review & editing, 1 Jifeng Bian, Formal analysis, Investigation, Methodology, Writing – review & editing, 1 M. Heather West Greenlee, Conceptualization, Investigation, Supervision, Writing – review & editing, 2 and Justin J. Greenlee, Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Project administration, Resources, Supervision, Writing – original draft, Writing – review & editingcorresponding author 1 ,* Jason C. Bartz, Editor
Abstract
Prion agents occur in strains that are encoded by the structure of the misfolded prion protein (PrPSc). Prion strains can influence disease phenotype and the potential for interspecies transmission. Little is known about the potential transmission of prions between sheep and deer. Previously, the classical US scrapie isolate (No.13-7) had a 100% attack rate in white-tailed deer after oronasal challenge. The purpose of this study was to test the susceptibility of sheep to challenge with the scrapie agent after passage through white-tailed deer (WTD scrapie). Lambs of various prion protein genotypes were oronasally challenged with WTD scrapie. Sheep were euthanized and necropsied upon development of clinical signs or at the end of the experiment (72 months post-inoculation). Enzyme immunoassay, western blot, and immunohistochemistry demonstrated PrPSc in 4 of 10 sheep with the fastest incubation occurring in VRQ/VRQ sheep, which contrasts the original No.13-7 inoculum with a faster incubation in ARQ/ARQ sheep. Shorter incubation periods in VRQ/VRQ sheep than ARQ/ARQ sheep after passage through deer was suggestive of a phenotype change, so comparisons were made in ovinized mice and with sheep with known strains of classical sheep scrapie: No. 13–7 and x-124 (that has a more rapid incubation in VRQ/VRQ sheep). After mouse bioassay, the WTD scrapie and x-124 isolates have similar incubation periods and PrPSc conformational stability that are markedly different than the original No. 13–7 inoculum. Furthermore, brain tissues of sheep with WTD scrapie and x-124 scrapie have similar patterns of immunoreactivity that are distinct from sheep with No. 13–7 scrapie. Multiple lines of evidence suggest a phenotype switch when No. 13–7 scrapie prions are passaged through deer. This represents one example of interspecies transmission of prions resulting in the emergence or selection of new strain properties that could confound disease eradication and control efforts.
Author summary
Passage of the sheep-derived US No. 13–7 classical scrapie isolate through white-tailed deer results in a change in disease phenotype that is observed when the deer-passaged scrapie agent is inoculated back into sheep or ovinized mice. Upon passage back to sheep, the relationship between incubation period and sheep PRNP genotype is reversed from the original inoculum. Whereas inoculation with the original No.13-7 scrapie agent results in a shorter incubation period in sheep with the ARQ/ARQ genotype as compared to VRQ/VRQ sheep, the deer-passaged scrapie agent results in a shorter incubation period in VRQ/VRQ sheep. In addition, passage of the No.13-7 isolate through deer results in a change in the pattern of PrPSc deposition in the brain of affected sheep. Taken together with the results of bioassay and conformational stability assays this work supports emergence of strain properties different from the No. 13–7 inoculum and consistent with another classical scrapie strain called x-124. Interspecies transmission of the classical scrapie agent can result in a phenotype switch through emergence of new scrapie strain properties that could potentially expand the potential host range.
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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.
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imals; 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.
snip...see;
BSE: TIME TO TAKE HB PARRY SERIOUSLY
HB Parry Seriously’ (YB88/6.8/4.1) IF the scrapie agent is generated from ovine DNA and thence causes disease in other species, then perhaps, bearing in mind the possible role of scrapie in CJD of humans (Davinpour et al, 1985), scrapie and not BSE should be the notifiable disease. https://web.archive.org/web/20030714133556/http://www.bseinquiry.gov.uk/files/yb/1988/06/08004001.pdf
1988: Letter entitled ‘Scrapie, Time to take HB Parry Seriously’ (YB88/6.8/4.1) 24. In this letter I stated that BSE had been officially confirmed as a TSE (when much of the veterinary profession still favoured a variety of alternate hypotheses). I also suggested that scrapie should be made a notifiable disease, and drew attention to the work of HB 'James' Parry and the possibility that natural scrapie in sheep might be of genetic origin. 25. I withdrew the letter following advice from Professor Barlow (who as far as I can recall had been contacted by MAFF and the Veterinary Record) that it might not be in my interests to pursue publication at that moment in time. 26. I received a letter from the then editor, Edward Boden, questioning my permission to release the information that BSE was indeed a proven TSE. I had no permission, though was unaware that any was needed, to inform my profession of this urgent and important fact.
1992: McGill and Wood 27. This paper summarises views as to why an open debate on TSEs and in particular scrapie were and remain essential. We drew attention to the work of Parry, Prusiner and others, and outlined novel explanations for recent research findings in light of such work. We suggested that not all the relevant questions were being asked in the interpretation of data. In particular, the possibility that the infectious agent was being generated de novo from the genome (the PrP gene) in certain families of sheep, was still not being considered, despite a body of scientific data going back over 30 years. It was to be a further 5 years before publications from Government laboratories would start to cite Parry’s work as a possibly correct theory. 28. The refereeing process for this work was at the time not transparent, and I have yet to be informed as to why this remains unpublished.
SNIP...SEE;
1: J Infect Dis 1980 Aug;142(2):205-8
Oral transmission of kuru, Creutzfeldt-Jakob disease, and scrapie to nonhuman primates.
Gibbs CJ Jr, Amyx HL, Bacote A, Masters CL, Gajdusek DC.
Kuru and Creutzfeldt-Jakob disease of humans and scrapie disease of sheep and goats were transmitted to squirrel monkeys (Saimiri sciureus) that were exposed to the infectious agents only by their nonforced consumption of known infectious tissues. The asymptomatic incubation period in the one monkey exposed to the virus of kuru was 36 months; that in the two monkeys exposed to the virus of Creutzfeldt-Jakob disease was 23 and 27 months, respectively; and that in the two monkeys exposed to the virus of scrapie was 25 and 32 months, respectively. Careful physical examination of the buccal cavities of all of the monkeys failed to reveal signs or oral lesions. One additional monkey similarly exposed to kuru has remained asymptomatic during the 39 months that it has been under observation.
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The successful transmission of kuru, Creutzfeldt-Jakob disease, and scrapie by natural feeding to squirrel monkeys that we have reported provides further grounds for concern that scrapie-infected meat may occasionally give rise in humans to Creutzfeldt-Jakob disease.
PMID: 6997404
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6997404&dopt=Abstract
Recently the question has again been brought up as to whether scrapie is transmissible to man. This has followed reports that the disease has been transmitted to primates. One particularly lurid speculation (Gajdusek 1977) conjectures that the agents of scrapie, kuru, Creutzfeldt-Jakob disease and transmissible encephalopathy of mink are varieties of a single "virus". The U.S. Department of Agriculture concluded that it could "no longer justify or permit scrapie-blood line and scrapie-exposed sheep and goats to be processed for human or animal food at slaughter or rendering plants" (ARC 84/77)" The problem is emphasised by the finding that some strains of scrapie produce lesions identical to the once which characterise the human dementias"
Whether true or not. the hypothesis that these agents might be transmissible to man raises two considerations. First, the safety of laboratory personnel requires prompt attention. Second, action such as the "scorched meat" policy of USDA makes the solution of the acrapie problem urgent if the sheep industry is not to suffer grievously.
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76/10.12/4.6
Nature. 1972 Mar 10;236(5341):73-4.
Transmission of scrapie to the cynomolgus monkey (Macaca fascicularis).
Gibbs CJ Jr, Gajdusek DC.
Nature 236, 73 - 74 (10 March 1972); doi:10.1038/236073a0
Transmission of Scrapie to the Cynomolgus Monkey (Macaca fascicularis)
C. J. GIBBS jun. & D. C. GAJDUSEK
National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, Maryland
SCRAPIE has been transmitted to the cynomolgus, or crab-eating, monkey (Macaca fascicularis) with an incubation period of more than 5 yr from the time of intracerebral inoculation of scrapie-infected mouse brain. The animal developed a chronic central nervous system degeneration, with ataxia, tremor and myoclonus with associated severe scrapie-like pathology of intensive astroglial hypertrophy and proliferation, neuronal vacuolation and status spongiosus of grey matter. The strain of scrapie virus used was the eighth passage in Swiss mice (NIH) of a Compton strain of scrapie obtained as ninth intracerebral passage of the agent in goat brain, from Dr R. L. Chandler (ARC, Compton, Berkshire).
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.
2. Determined that pigs naturally exposed to chronic wasting disease (CWD) may act as a reservoir of CWD infectivity. Chronic wasting disease is a naturally occurring, fatal, neurodegenerative disease of cervids. The potential for swine to serve as a host for the agent of CWD disease is unknown. The purpose of this study was to investigate the susceptibility of swine to the CWD agent following experimental oral or intracranial inoculation. Pigs were assigned to 1 of 3 groups: intracranially inoculated; orally inoculated; or non-inoculated. At market weight age, half of the pigs in each group were tested ('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 multiple diagnostic methods. Brain samples from selected pigs were bioassayed in mice expressing porcine prion protein. Some pigs from each inoculated group were positive by one or more tests. Bioassay was positive in 4 out of 5 pigs assayed. Although only small amounts of PrPSc were detected using sensitive methods, this study demonstrates that pigs can serve as hosts for CWD. 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. 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. The current feed ban in the U.S. is based exclusively on keeping tissues from TSE infected cattle from entering animal feeds. These results indicating the susceptibility of pigs to CWD, 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.
Scrapie and CJD, Suspect Symptoms, Like Lambs To the Slaughter, a review 2022
2001
Suspect symptoms
What if you can catch old-fashioned CJD by eating meat from a sheep infected with scrapie?
28 Mar 01
Like lambs to the slaughter
31 March 2001
by Debora MacKenzie Magazine issue 2284.
FOUR years ago, Terry Singeltary watched his mother die horribly from a degenerative brain disease. Doctors told him it was Alzheimer's, but Singeltary was suspicious. The diagnosis didn't fit her violent symptoms, and he demanded an autopsy. It showed she had died of sporadic Creutzfeldt-Jakob disease.
Most doctors believe that sCJD is caused by a prion protein deforming by chance into a killer. But Singeltary thinks otherwise. He is one of a number of campaigners who say that some sCJD, like the variant CJD related to BSE, is caused by eating meat from infected animals. Their suspicions have focused on sheep carrying scrapie, a BSE-like disease that is widespread in flocks across Europe and North America.
Now scientists in France have stumbled across new evidence that adds weight to the campaigners' fears. To their complete surprise, the researchers found that one strain of scrapie causes the same brain damage in mice as sCJD.
"This means we cannot rule out that at least some sCJD may be caused by some strains of scrapie," says team member Jean-Philippe Deslys of the French Atomic Energy Commission's medical research laboratory in Fontenay-aux-Roses, south-west of Paris. Hans Kretschmar of the University of Göttingen, who coordinates CJD surveillance in Germany, is so concerned by the findings that he now wants to trawl back through past sCJD cases to see if any might have been caused by eating infected mutton or lamb.
Scrapie has been around for centuries and until now there has been no evidence that it poses a risk to human health. But if the French finding means that scrapie can cause sCJD in people, countries around the world may have overlooked a CJD crisis to rival that caused by BSE.
Deslys and colleagues were originally studying vCJD, not sCJD. They injected the brains of macaque monkeys with brain from BSE cattle, and from French and British vCJD patients. The brain damage and clinical symptoms in the monkeys were the same for all three. Mice injected with the original sets of brain tissue or with infected monkey brain also developed the same symptoms.
As a control experiment, the team also injected mice with brain tissue from people and animals with other prion diseases: a French case of sCJD; a French patient who caught sCJD from human-derived growth hormone; sheep with a French strain of scrapie; and mice carrying a prion derived from an American scrapie strain. As expected, they all affected the brain in a different way from BSE and vCJD. But while the American strain of scrapie caused different damage from sCJD, the French strain produced exactly the same pathology.
"The main evidence that scrapie does not affect humans has been epidemiology," says Moira Bruce of the neuropathogenesis unit of the Institute for Animal Health in Edinburgh, who was a member of the same team as Deslys. "You see about the same incidence of the disease everywhere, whether or not there are many sheep, and in countries such as New Zealand with no scrapie." In the only previous comparisons of sCJD and scrapie in mice, Bruce found they were dissimilar.
But there are more than 20 strains of scrapie, and six of sCJD. "You would not necessarily see a relationship between the two with epidemiology if only some strains affect only some people," says Deslys. Bruce is cautious about the mouse results, but agrees they require further investigation. Other trials of scrapie and sCJD in mice, she says, are in progress.
People can have three different genetic variations of the human prion protein, and each type of protein can fold up two different ways. Kretschmar has found that these six combinations correspond to six clinical types of sCJD: each type of normal prion produces a particular pathology when it spontaneously deforms to produce sCJD.
But if these proteins deform because of infection with a disease-causing prion, the relationship between pathology and prion type should be different, as it is in vCJD. "If we look at brain samples from sporadic CJD cases and find some that do not fit the pattern," says Kretschmar, "that could mean they were caused by infection."
There are 250 deaths per year from sCJD in the US, and a similar incidence elsewhere. Singeltary and other US activists think that some of these people died after eating contaminated meat or "nutritional" pills containing dried animal brain. Governments will have a hard time facing activists like Singeltary if it turns out that some sCJD isn't as spontaneous as doctors have insisted.
Deslys's work on macaques also provides further proof that the human disease vCJD is caused by BSE. And the experiments showed that vCJD is much more virulent to primates than BSE, even when injected into the bloodstream rather than the brain. This, says Deslys, means that there is an even bigger risk than we thought that vCJD can be passed from one patient to another through contaminated blood transfusions and surgical instruments.
Adaptation of the bovine spongiform encephalopathy agent to primates and comparison with Creutzfeldt– Jakob disease: Implications for human health
Corinne Ida Lasmézas, Jean-Guy Fournier, Virginie Nouvel, +8, and Jean-Philippe DeslysAuthors Info & Affiliations
March 20, 2001
98 (7) 4142-4147
Abstract
There is substantial scientific evidence to support the notion that bovine spongiform encephalopathy (BSE) has contaminated human beings, causing variant Creutzfeldt–Jakob disease (vCJD). This disease has raised concerns about the possibility of an iatrogenic secondary transmission to humans, because the biological properties of the primate-adapted BSE agent are unknown. We show that (i) BSE can be transmitted from primate to primate by intravenous route in 25 months, and (ii) an iatrogenic transmission of vCJD to humans could be readily recognized pathologically, whether it occurs by the central or peripheral route. Strain typing in mice demonstrates that the BSE agent adapts to macaques in the same way as it does to humans and confirms that the BSE agent is responsible for vCJD not only in the United Kingdom but also in France. The agent responsible for French iatrogenic growth hormone-linked CJD taken as a control is very different from vCJD but is similar to that found in one case of sporadic CJD and one sheep scrapie isolate. These data will be key in identifying the origin of human cases of prion disease, including accidental vCJD transmission, and could provide bases for vCJD risk assessment.
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Discussion
One aim of this study was to determine the risk of secondary transmission to humans of vCJD, which is caused not by a primarily human strain of TSE agent but by the BSE strain having passed the species barrier to humans. This risk is tightly linked to the capacity of the BSE agent to adapt to primates and harbor enhanced virulence (i.e., induce disease after a short incubation period and provoke disease even if highly diluted) and to its pathogenicity after inoculation by the peripheral route. With respect to the latter, there are huge variations between different TSE agent strains and hosts. For example, the BSE agent is pathogenic to pigs after i.c. inoculation but not after oral administration (23). Thus, we wanted to know to what extent the BSE/vCJD agent is pathogenic to humans by the i.c. and i.v. routes. To achieve this, we used the macaque model. To monitor the evolution of the BSE agent in primates, but also to verify the identity of French vCJD, we conducted parallel transmission to C57BL/6 mice, allowing strain-typing. The experimental scheme is depicted in Fig. 1.
Characterization of the BSE Agent in Primates.
The identity of the lesion profiles obtained from the brains of the French patient with vCJD, two British patients with vCJD, and nonhuman primates infected with BSE provides experimental demonstration of the fact that the BSE agent strain has been transmitted to humans both in the U.K. and in France. Further, it lends support to the validity of the macaque model as a powerful tool for the study of vCJD. As far as the evolution of the BSE agent in primates is concerned, we observed an interesting phenomenon: at first passage of BSE in macaques and with vCJD, there was a polymorphism of the lesion profile in mice in the hippocampal region, with about half of them harboring much more severe vacuolation than the mice inoculated with cattle BSE. At second passage, the polymorphism tended to disappear, with all mice showing higher vacuolation scores in the hippocampus than cattle BSE mice. This observation suggests the appearance of a variant of the BSE agent at first passage in primates and its clonal selection during second passage in primates. The lesion profiles showed that it was still the BSE agent, but the progressive appearance of a “hippocampal signature” hallmarked the evolution toward a variant by essence more virulent to primates.
Characterization of the CJD and Scrapie Strains.
Controls were set up by transmitting one French and one U.S. scrapie isolate from ruminants as well as French sCJD and iCJD cases from humans. None of these revealed a lesion profile or transmission characteristics similar or close to those of BSE or vCJD, respectively, thus extending to the present French scrapie isolate the previous observation that the BSE agent was different from all known natural scrapie strains (4, 24).
The lesion profiles of sCJD and iCJD differed only slightly in severity of the lesions, but not in shape of the profile, revealing the identity of the causative agents. One of us reported the absence of similarity between sCJD (six cases) and U.K. scrapie (eight cases) in transmission characteristics in mice (4). Herein, we made the striking observation that the French natural scrapie strain (but not the U.S. scrapie strain) has the same lesion profile and transmission times in C57BL/6 mice as do the two human TSE strains studied. This strain “affiliation” was confirmed biochemically. There is no epidemiological evidence for a link between sheep scrapie and the occurrence of CJD in humans (25). However, such a link, if it is not a general rule, would be extremely difficult to establish because of the very low incidence of CJD as well as the existence of different isolates in humans and multiple strains in scrapie. Moreover, scrapie is transmissible to nonhuman primates (26). Thus, there is still a possibility that in some instances TSE strains infecting humans do share a common origin with scrapie, as pointed out by our findings.
Transmission of vCJD and BSE to Nonhuman Primates.
vCJD transmitted readily to the cynomolgus macaque after 2 years of incubation, which was comparable to the transmission obtained from first-passaged macaque BSE and much shorter than the interspecies transmission of BSE. Starting with 100 mg of BSE–macaque brain material, dilutions up to 4 μg still provoked disease. These data suggest that the BSE agent rapidly adapts to primates accompanied by enhanced virulence.
Examination of macaque brain inoculated with vCJD revealed a similar pathology to that with second-passage BSE. The distribution of vacuolation and gliosis, as well as the pattern of PrP deposition, including the dense, sometimes florid plaques, were similar to the human vCJD and the BSE hallmarks of the first passage (1, 2). These data show that the phenotype of BSE in primates is conserved over two passages. Moreover, they confirm that the BSE agent behaves similarly in humans and macaques, a precious finding that will prove useful in the near future for the design of pathogenesis or therapeutic studies. Because of the number of macaques examined in this study, we can now reliably state that the pathology, in particular the PrP deposition pattern provoked by BSE, is similar in older and very young animals. However, plaque deposition is greater, and mature florid plaques were more numerous, in the young, which may be correlated with a longer duration of the clinical phase observed in this animal (2). This is important with regard to the fact that vCJD has been diagnosed mainly in teenagers and young adults, which raises the concern that older patients may have been misdiagnosed because of an alternative phenotype of the disease.
One should bear in mind, however, that cynomolgus macaques are all homozygotes for methionine at codon 129 of the PrP gene. Thus, our observations may not be relevant to humans carrying one or both valine alleles; however, all patients with vCJD reported to date have been M/M at this position (27). Intravenous Transmissions to Nonhuman Primates.
Brain pathology was identical in macaques inoculated i.c. and i.v. The i.v. route proved to be very efficient for the transmission of BSE, as shown by the 2-year survival of the animals, which is only 5 months longer than that obtained after inoculating the same amount of agent i.c. As the i.v. injection of the infectious agent implies per se a delayed neuroinvasion compared with a direct inoculation in the brain, this slight lengthening of the incubation period cannot, at this stage, be interpreted as a lower efficiency of infection as regards the i.c. route. These data should be taken into account in the risk assessment of iatrogenic vCJD transmission by i.v. administration of biological products of human origin. They also constitute an incentive for a complete i.v. titration.
Conclusions
From BSE and vCJD transmissions in nonhuman primates, a number of conclusions can be drawn that are of major importance for human health: (i) human-adapted BSE appears to be a variant of the BSE agent that is more virulent for humans than cattle BSE and is efficiently transmitted by the peripheral route; (ii) the detection of vCJD in unusually young patients is probably not because of a lack of diagnosis of cases in older patients, thus raising the question of the source of human contamination with BSE early in life; and (iii) iatrogenic transmissions from patients with vCJD would be readily recognized by using the same diagnostic criteria as those applied to vCJD [clinical and pathological criteria (27) comprising neuronal loss and gliosis in the thalamus correlated with high MRI signal (28, 29)], whether such contaminations had occurred by the central or i.v. route. Primary and iatrogenic cases of vCJD could be distinguished on the basis of the patient's clinical history.
The risk assessment of biological products of human origin, notably those derived from blood, has been deeply modified by the appearance of vCJD. We confirm that the BSE agent has contaminated humans not only in the U.K. and the Republic of Ireland but also in France, and we show that its pathogenic properties for primates are being enhanced by a primary passage in humans. Considering the flow of potentially contaminated bovine-derived products between 1980 and 1996, it is obvious that further vCJD cases may occur outside the U.K. Thus, and in the light of the present study, it is necessary to sustain worldwide CJD surveillance regardless of national BSE incidence and to take all precautionary measures to avoid iatrogenic transmissions from vCJD.
THURSDAY, JANUARY 4, 2024
Disease phenotype of classical sheep scrapie is changed upon experimental passage through white-tailed deer
WEDNESDAY, JANUARY 3, 2024
PROCEEDINGS ONE HUNDRED AND TWENTY SIXTH ANNUAL MEETING USAHA CWD, Scrapie, and BSE, October 2022 updated science 2024
Wednesday, May 24, 2023
***> WAHIS, WOAH, OIE, United States of America Bovine spongiform encephalopathy Immediate notification
SATURDAY, MAY 20, 2023
***> Tennessee State Veterinarian Alerts Cattle Owners to Disease Detection Mad Cow atypical L-Type BSE
MAY 19, 2023
2 weeks before the announcement of this recent mad cow case in the USA, i submitted this to the APHIS et al;
***> APPRX. 2 weeks before the recent mad cow case was confirmed in the USA, in Tennessee, atypical L-Type BSE, I submitted this to the APHIS et al;
Document APHIS-2023-0027-0001 BSE Singeltary Comment Submission May 2, 2023
''said 'burden' cost, will be a heavy burden to bear, if we fail with Bovine Spongiform Encephalopathy BSE TSE Prion disease, that is why this information collection is so critical''...
spontaneous BSE? big outbreak of spontaneous mad cow disease evidently, around the same time, strange;
WEDNESDAY, NOVEMBER 08, 2023
Ireland Atypical BSE confirmed November 3 2023
TUESDAY, NOVEMBER 14, 2023
Ireland Atypical BSE case, 3 progeny of case cow to be culled
SUNDAY, JULY 16, 2023
Switzerland Atypical BSE detected in a cow in the canton of St. Gallen
WAHIS, WOAH, OIE, REPORT Switzerland Bovine Spongiform Encephalopathy Atypical L-Type
Switzerland Bovine Spongiform Encephalopathy Atypical L-Type
Switzerland - Bovine spongiform encephalopathy - Immediate notification
Monday, March 20, 2023
WAHIS, WOAH, OIE, REPORT United Kingdom Bovine Spongiform Encephalopathy Atypical H-Type
BRAZIL BSE START DATE 2023/01/18
BRAZIL BSE CONFIRMATION DATE 2023/02/22
BRAZIL BSE END DATE 2023/03/03
SPAIN BSE START DATE 2023/01/21
SPAIN BSE CONFIRMATION DATE 2023/02/03
SPAIN BSE END DATE 2023/02/06
NETHERLANDS BSE START DATE 2023/02/01
NETHERLANDS BSE CONFIRMATION DATE 2023/02/01
NETHERLANDS BSE END DATE 2023/03/13
PLEASE NOTE, USDA ET AL ONLY TESTING <25k CATTLE FOR MAD COW DISEASE, woefully inadequate, yet USDA just documented a case Atypical L-Type BSE, the most virulent strain to date...
Monday, May 22, 2023
***> BSE TSE Prion MAD COW TESTING IN THE USA COMPARED TO OTHER COUNTRIES?
FRIDAY, JANUARY 20, 2023
EPIDEMIOLOGY OF SCRAPIE IN THE UNITED STATES
WEDNESDAY, FEBRUARY 03, 2021
Scrapie TSE Prion United States of America a Review February 2021 Singeltary et al
WEDNESDAY, MARCH 16, 2022
SHEEP BY-PRODUCTS AND WHAT ABOUT Scrapie TSE PrP and Potential Zoonosis?
WEDNESDAY, DECEMBER 8, 2021
Importation of Sheep, Goats, and Certain Other Ruminants AGENCY: Animal APHIA, USDA, FINAL RULE [Docket No. APHIS–2009–0095] RIN 0579–AD10
FRIDAY, DECEMBER 10, 2021
USDA APHIS National Scrapie Eradication Program October 2021 Monthly Report Fiscal Year 2022
MONDAY, NOVEMBER 29, 2021
Experimental Oronasal Transmission of Chronic Wasting Disease Agent from White-Tailed Deer to Suffolk Sheep Volume 27, Number 12—December 2021 Dispatch
FRIDAY, DECEMBER 10, 2021
Scrapie at Abattoir: Monitoring, Control, and Differential Diagnosis of Wasting Conditions during Meat Inspection
THURSDAY, DECEMBER 7, 2023
Chronic Wasting Disease CWD TSE Prion Cervid Update By State December 2023
(Long Version)
(Short Version)
THURSDAY, MARCH 07, 2024
Texas TPWD CWD Cases Jump to 663 Confirmed To Date
