Tuesday, November 24, 2020

Studies in bank voles reveal strain differences between chronic wasting disease prions from Norway and North America

Studies in bank voles reveal strain differences between chronic wasting disease prions from Norway and North America

Romolo Nonnoa,1, Michele A. Di Baria , Laura Pirisinua , Claudia D’Agostinoa , Ilaria Vannia , Barbara Chiappinia , Stefano Marcona , Geraldina Riccardia , Linh Tranb , Turid Vikørenb , Jørn Vågeb , Knut Madslienb , Gordon Mitchellc , Glenn C. Tellingd , Sylvie L. Benestadb,2, and Umberto Agrimia,2

a Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, 00161 Rome, Italy; b World Organization for Animal Health Reference Laboratory for Chronic Wasting Disease, Norwegian Veterinary Institute, N-0106 Oslo, Norway; c National and World Organization for Animal Health Reference Laboratory for Scrapie and Chronic Wasting Disease, Canadian Food Inspection Agency, Ottawa, ON K2H 8P9, Canada; and d Prion Research Center, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80525 Edited by Michael B. A. Oldstone, Scripps Research Institute, La Jolla, CA, and approved November 3, 2020 (received for review June 26, 2020)

Chronic wasting disease (CWD) is a relentless epidemic disorder caused by infectious prions that threatens the survival of cervid populations and raises increasing public health concerns in North America. In Europe, CWD was detected for the first time in wild Norwegian reindeer (Rangifer tarandus) and moose (Alces alces) in 2016. In this study, we aimed at comparing the strain properties of CWD prions derived from different cervid species in Norway and North America. Using a classical strain typing approach involving transmission and adaptation to bank voles (Myodes glareolus), we found that prions causing CWD in Norway induced incubation times, neuropathology, regional deposition of misfolded prion protein aggregates in the brain, and size of their proteaseresistant core, different from those that characterize North American CWD. These findings show that CWD prion strains affecting Norwegian cervids are distinct from those found in North America, implying that the highly contagious North American CWD prions are not the proximate cause of the newly discovered Norwegian CWD cases. In addition, Norwegian CWD isolates showed an unexpected strain variability, with reindeer and moose being caused by different CWD strains. Our findings shed light on the origin of emergent European CWD, have significant implications for understanding the nature and the ecology of CWD in Europe, and highlight the need to assess the zoonotic potential of the new CWD strains detected in Europe.

Prion diseases, otherwise known as transmissible spongiform encephalopathies (TSEs), are invariably fatal infectious neurodegenerative disorders of animals and humans. Prions are composed largely or exclusively of self-replicating protein aggregates of PrPSc, which is a misfolded isoform of the cellular prion protein (PrPC). Most human prion diseases, including Creutzfeldt–Jakob disease (CJD) and sporadic fatal insomnia, occur sporadically and are thought to result from the spontaneous misfolding of PrPC into PrPSc. Mutations in the coding sequence of the gene encoding PrP (PRNP) in inherited diseases such as familial CJD, fatal familial insomnia, and Gerstmann– Sträussler–Scheinker syndrome are thought to potentiate spontaneous misfolding of PrPC to PrPSc (1). The intrinsic transmissibility of prions has also resulted in epidemics of acquired prion diseases (2), with significant public health consequences. Examples include iatrogenic CJD transmission caused by prion-contaminated human growth hormone preparations and dura mater grafts, and variant CJD resulting from human exposure to bovine spongiform encephalopathy (BSE) prions.

Animal prion diseases also occur as contagious forms giving rise to outbreaks such as classical scrapie in small ruminants and chronic wasting disease (CWD) in cervids (3). In addition to their impact on human health, exemplified by zoonotic BSE transmission (2), epidemic animal prion diseases, such as CWD in North America (NA) (4), have significant ecologic and economic consequences. First identified in captive deer in Northern Colorado in the 1960s, CWD is now known to affect wild and farmed cervid populations in 26 states and three Canadian provinces. Disease was introduced to the Republic of Korea following importation of subclinical elk (Cervus canadensis) from Canada (5). The irrevocable spread of CWD in NA raises serious concerns about the survival of cervid populations, as well as for the risks posed to other animals and to humans (6). Prion diseases are caused by different prion strains, which are thought to be encoded by conformational variants of PrPSc (7, 8). While different PrPSc conformers can be discriminated using biochemical approaches, assessing infectious properties of prions in susceptible hosts remains the gold standard for strain characterization. Such analyses are of the utmost importance for trace-back studies of iatrogenic (9, 10) or zoonotic prion strains (11, 12), for identifying spillover hosts (13), for estimating the zoonotic potential of classical and atypical scrapie strains (14, 15), and for understanding the epidemiology and evolution of strains in contagious prion diseases (16–20).

In Europe, CWD was detected for the first time in wild Norwegian reindeer (Rangifer tarandus) and moose (Alces alces) in 2016 (21, 22). The emergence of CWD in Europe necessitates characterization of the strain properties of these CWD prions of uncertain origin to explore a possible link with NA CWD.

Knowledge about Norwegian CWD strains is essential to assess their risk to animal and human health, and to develop evidencebased policies to control and limit the spread of the disease (23). In a previous study, we found that bank voles carrying isoleucine at codon 109 (Bv109I) are highly susceptible to CWD isolates from the United States. After subpassage in Bv109I, the same vole-adapted CWD strain was isolated from NA mule deer (Odocoileus hemionus), white-tailed deer (Odocoileus virginianus), and elk isolates, which was characterized by an unprecedented short disease duration and peculiar and recognizable strain features (24). Here, we extended our previous characterizations of NA CWD isolates and compared the biological properties of CWD isolates from Norway and NA by transmission to the Bv109I genetic line of bank voles.


Bank Voles Are Susceptible to Canadian and Norwegian CWD Isolates. We selected Norwegian and Canadian CWD isolates (Table 1) whose molecular and pathological features have been previously reported (22). Direct comparison of the PrPSc types in the brain homogenates used for the present bioassay studies (SI Appendix, Fig. S1) confirmed that the three Norwegian moose CWD cases are characterized by PrPSc features different from the Canadian isolates, while Norwegian reindeer share PrPSc characteristics with NA isolates (22).

All Bv109I inoculated with Canadian CWD isolates from elk (E-CA1 and E-CA2) and white-tailed deer (D-CA1) developed clinical disease with short incubation times (Table 1). In contrast, the Canadian moose inoculum (M-CA1) produced an incomplete attack rate and a longer mean survival time, largely explained by the extremely long survival time of a single Bv109I (SI Appendix, Fig. S2). The less efficient transmission of this Canadian moose isolate is consistent with a low prion infectious titer; this interpretation is supported by the lower level of PrPSc in this inoculum compared to other Canadian isolates (SI Appendix, Fig. S1). Bv109I inoculated with Norwegian moose isolates M-NO1, M-NO2, and M-NO3 developed CWD with longer disease kinetics compared to Canadian CWD isolates (Table 1). Transmission of Norwegian reindeer CWD isolates (R-NO1 and R-NO2) was inefficient, with only one R-NO1 inoculated vole developing disease, and no voles succumbing to disease after challenge with R-NO2. These negative and inefficient transmissions are not the result of low levels of PrPSc in brain homogenates of these Norwegian CWD isolates (SI Appendix, Fig. S1).

Overall, three different patterns of transmission in Bv109I were observed from 1) Canadian isolates (short survival time), 2) Norwegian moose (long survival time), and 3) Norwegian reindeer (barely transmissible in Bv109I) (SI Appendix, Fig. S2).


Chronic wasting disease (CWD) is a highly contagious disease caused by prions that affects several cervid species and is relentlessly spreading across North America. Very recently, CWD was detected for the first time in Europe. In this study, we found that Norwegian CWD strains are distinct from those causing the epidemic in North America. Moreover, we show that Norwegian reindeer and moose are affected by different CWD strains, revealing an unprecedented prion strain variation in Norwegian wild cervid populations. These findings indicate that North American CWD prions are not the proximate cause of the newly discovered Norwegian CWD cases and have implications for CWD control strategies in Europe, as well as for the safety of humans.



Our finding that CWD in European cervids is caused by prion strains with properties different from the prevalent CWD strain that currently sustains the NA epidemic has important implications for understanding the origin and nature of CWD in Europe. The variety of strains observed in Norwegian cervid species raises questions about the ecology of the disease compared to NA and has implications for the proper targeting of surveillance efforts and control strategies in Europe. Most importantly, all of the available knowledge about diagnostics, pathogenesis, transmissibility, species range, and zoonotic potential of CWD derive from the study of NA CWD. Since the CWD strains in Europe are different from NA CWD, the present knowledge is not easily transferrable to the European situation and a reevaluation of the transmissibility and the zoonotic potential of the new CWD strains here identified is needed. snip...see full text;

spontaneous LMAO!

***> 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. <***

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


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.

Incomplete inactivation of atypical scrapie following recommended autoclave decontamination procedures

WEDNESDAY, MAY 29, 2019 

Incomplete inactivation of atypical scrapie following recommended autoclave decontamination procedures

Research Project: Pathobiology, Genetics, and Detection of Transmissible Spongiform Encephalopathies Location: Virus and Prion Research

Title: Efficient transmission of US scrapie agent by intralingual route to genetically susceptible sheep with a low dose inoculum 

Author item MAMMADOVA, NAJIBA - Oak Ridge Institute For Science And Education (ORISE) item CASSMANN, ERIC - Oak Ridge Institute For Science And Education (ORISE) item Greenlee, Justin

Submitted to: Research in Veterinary Science Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/10/2020 Publication Date: 10/20/2020 Citation: Mammadova, N., Cassmann, E., Greenlee, J.J. 2020. Efficient transmission of US scrapie agent by intralingual route to genetically susceptible sheep with a low dose inoculum. Research in Veterinary Science. 132: p. 217-220. https://doi.org/10.1016/j.rvsc.2020.06.010. DOI: https://doi.org/10.1016/j.rvsc.2020.06.010 Interpretive Summary: Scrapie is a fatal disease of sheep and goats that causes damaging changes in the brain. The infectious agent is an abnormal protein called a prion that has misfolded from its normal state. Previous work has defined two distinct isolates of classical scrapie, x124 and No. 13-7, that have differences in incubation periods and susceptibility in sheep with different genetic backgrounds. It has been shown that after inoculation with US isolate x124, susceptibility and incubation period are associated with valine at codon 136 (V136) of the prion protein: sheep with two V codons (VV136) have the shortest incubation periods, followed by sheep with one V codon and one A codon (AV136), while sheep with two A codons (AA136) only developed disease after inoculation via the intracerebral route. Sheep scrapie can be transmitted orally from ingestion of prions and it is possible that oral lesions may pose a risk for scrapie infection. In this study, we investigated infectivity of decreasing doses of the x124 scrapie agent (100mg, 50mg, 20mg, and 10mg) on incubation time and attack rate after experimental intralingual inoculation into susceptible AV136 sheep. Our results indicate that the lowest inoculum dose tested in this study effectively transmitted the x124 scrapie agent in AV136 sheep, with a 100 percent attack rate, and no significant difference in incubation times among sheep inoculated with varying doses. This study provides a starting point for future studies to assess the minimum infectious dose of the x124 scrapie agent in sheep. This information is important for determining the potential risk of scrapie occurrence in sheep flock and could be used by veterinarians and regulatory agencies.

Technical Abstract: Scrapie is a naturally occurring transmissible spongiform encephalopathy (TSE) in sheep and goats that results in accumulation of the misfolded prion protein (PrPSc) and progressive neurodegeneration. To date, two distinct US isolates of classical scrapie, x124 and No. 13-7, have been described with differences in incubation periods, neuroanatomical deposition profiles of PrPSc, as well as genotype susceptibilities. It has been shown that after inoculation with US isolate x124, susceptibility and incubation period are associated with valine at codon 136 (V136) of the prion protein: VRQ/VRQ had the shortest incubation periods, followed by VRQ/ARQ sheep, while ARQ/ARQ sheep only developed disease after inoculation via the intracerebral route. Additionally, sheep scrapie can be transmitted from ingestion of prions shed in the environment and/or bodily fluids, as well contaminated environmental sources. Therefore it is possible that oral lesions may facilitate susceptibility to scrapie transmission. In this study, we aim to investigate the infectivity of decreasing doses of the x124 scrapie agent (100mg, 50mg, 20mg, and 10mg) on incubation time and attack rate after experimental intralingual inoculation into susceptible VRQ/ARQ sheep. Our results indicate that the lowest inoculum dose tested in this study effectively transmitted the x124 scrapie agent in VRQ/ARQ sheep, with a 100% attack rate, and no significant difference in incubation times among sheep inoculated with varying doses. Moreover, immunohistochemistry and western blot analysis revealed similar biochemical and immunohistochemical features among the four cohorts of sheep irrespective of inoculum dose. This study provides a starting point for further investigation to determine the minimum infectious dose of x124 scrapie in sheep and its effect on attack rate and incubation time, central for assessing the potential risk of scrapie occurrence in sheep flock.

Differentiation of ruminant transmissible spongiform encephalopathy isolate types, including bovine spongiform encephalopathy and CH1641 scrapie

J. G. Jacobs1, M. Sauer2, L. J. M. van Keulen1, Y. Tang2, A. Bossers1 and J. P. M. Langeveld1

1 Department of Infection Biology, Central Veterinary Institute of Wageningen UR, PO Box 65, 8200 AB Lelystad, The Netherlands 2 Department of Molecular Pathogenesis and Genetics, Veterinary Laboratories Agency-Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK

Correspondence J. P. M. Langeveld jan.langeveld@wur.nl

With increased awareness of the diversity of transmissible spongiform encephalopathy (TSE) strains in the ruminant population, comes an appreciation of the need for improved methods of differential diagnosis. Exposure to bovine spongiform encephalopathy (BSE) has been associated with the human TSE, variant Creutzfeldt–Jakob disease, emphasizing the necessity in distinguishing low-risk TSE types from BSE. TSE type discrimination in ruminants such as cattle, sheep, goats and deer, requires the application of several prion protein (PrP)-specific antibodies in parallel immunochemical tests on brain homogenates or tissue sections from infected animals. This study uses in a single incubation step, three PrP-specific antibodies and fluorescent Alexa dye-labelled anti-mouse Fabs on a Western blot. The usual amount of brain tissue needed is 0.5 mg. This multiplex application of antibodies directed towards three different PrP epitopes enabled differential diagnosis of all established main features of classical scrapie, BSE and Nor98-like scrapie in sheep and goats, as well as the currently known BSE types C, H and L in cattle. Moreover, due to an antibody-dependent dual PrP-banding pattern, for the first time CH1641 scrapie of sheep can be reliably discriminated from the other TSE isolate types in sheep.

Among ovine TSEs, classical scrapie and Nor98 were discriminated from both Norwegian moose isolates, while CH1641 samples had molecular features partially overlapping with the moose, i.e. a low MW PrPres and the presence of CTF13. In contrast, moose PrPSc did not overlap with any bovine PrPSc. Indeed, the MW of moose PrPres was lower than H-BSE and similar to C-BSE and L-BSE PrPres, but the two bovine prions lacked additional PrPres fragments. 

Conclusions: Unexpectedly, PrPSc from Norwegian moose revealed features substantially different from all other CWD isolates. The PrPSc pattern of Norwegian moose was also different from Canadian moose, suggesting that the variant PrPSc type observed does not simply reflect a host factor and could represent a new CWD strain. Furthermore, PrPSc of Norwegian moose can be easily discriminated from all BSE types, classical scrapie and Nor98, while showing significant overlapping only with CH1641. Bioassay in voles will help to clarify whether the different PrPSc types observed reflect the presence of a new CWD strain in Norwegian moose, and its relationships with known animal TSEs. 

References: 1Benestad et al, Vet Res (2016}47:88 


please see;

***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.

***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.


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.

Monday, November 30, 2009
Thursday, December 20, 2012

This surveillance plan is designed to speed the eradication of classical scrapie. Cases of nonclassical (Nor98-like) scrapie will be found because of testing for classical scrapie but the plan is not designed to maximize these detections. Nor98-like scrapie has its own unique characteristics, and the Animal and Plant Health Inspection Service (APHIS) and the OIE have concluded that it is “clinically, pathologically, biochemically, and epidemiologically unrelated to classical scrapie, may not be contagious and may, in fact, be a spontaneous degenerative condition of older sheep.” As a result, APHIS does not restrict or depopulate animals exposed to Nor98-like scrapie.

***> As a result, APHIS does not restrict or depopulate animals exposed to Nor98-like scrapie.

incredible stupidity, not based on sound science, see;

***> Thus, atypical scrapie is recognized as a separate, nonreportable disease by the World Organization for Animal Health (OIE).

''as usual, OIE USDA et al put cart before horse, and put human and animal life at risk...terry''

Atypical scrapie has been transmitted experimentally to AHQ sheep by the intracranial145 and oral146 routes. An increased risk of atypical scrapie has also been identified in sheep with the AF141RQ haplotype.137 Atypical scrapie does experimentally transmit to sheep with the AL141RQ haplotype but with very long incubation periods without clinical signs.123 Furthermore, sheep with the ARR haplotype, which confers resistance to classical scrapie and is the cornerstone of genotype-based eradication programs, do not appear to be protected against developing atypical scrapie.41,137

Atypical scrapie has also been reported in goats,103,142 where the molecular profile on western blot is similar to atypical scrapie in sheep, but the distribution of lesions within the brain is more rostral (thalamus and midbrain) than atypical scrapie of sheep.142 Similar to sheep with atypical scrapie, histidine substitution at PRNP codon 154 is a risk factor for atypical scrapie in goats,32 and PrPSc has not been demonstrated in the lymphoid tissues of affected goats.142


A newly identified type of scrapie agent can naturally infect sheep with resistant PrP genotypes

Annick Le Dur*,?, Vincent Béringue*,?, Olivier Andréoletti?, Fabienne Reine*, Thanh Lan Laï*, Thierry Baron§, Bjørn Bratberg¶, Jean-Luc Vilotte?, Pierre Sarradin**, Sylvie L. Benestad¶, and Hubert Laude*,?? +Author Affiliations

*Virologie Immunologie Moléculaires and ?Génétique Biochimique et Cytogénétique, Institut National de la Recherche Agronomique, 78350 Jouy-en-Josas, France; ?Unité Mixte de Recherche, Institut National de la Recherche Agronomique-Ecole Nationale Vétérinaire de Toulouse, Interactions Hôte Agent Pathogène, 31066 Toulouse, France; §Agence Française de Sécurité Sanitaire des Aliments, Unité Agents Transmissibles Non Conventionnels, 69364 Lyon, France; **Pathologie Infectieuse et Immunologie, Institut National de la Recherche Agronomique, 37380 Nouzilly, France; and ¶Department of Pathology, National Veterinary Institute, 0033 Oslo, Norway

***Edited by Stanley B. Prusiner, University of California, San Francisco, CA (received for review March 21, 2005)


Scrapie in small ruminants belongs to transmissible spongiform encephalopathies (TSEs), or prion diseases, a family of fatal neurodegenerative disorders that affect humans and animals and can transmit within and between species by ingestion or inoculation. Conversion of the host-encoded prion protein (PrP), normal cellular PrP (PrPc), into a misfolded form, abnormal PrP (PrPSc), plays a key role in TSE transmission and pathogenesis. The intensified surveillance of scrapie in the European Union, together with the improvement of PrPSc detection techniques, has led to the discovery of a growing number of so-called atypical scrapie cases. These include clinical Nor98 cases first identified in Norwegian sheep on the basis of unusual pathological and PrPSc molecular features and "cases" that produced discordant responses in the rapid tests currently applied to the large-scale random screening of slaughtered or fallen animals. Worryingly, a substantial proportion of such cases involved sheep with PrP genotypes known until now to confer natural resistance to conventional scrapie. Here we report that both Nor98 and discordant cases, including three sheep homozygous for the resistant PrPARR allele (A136R154R171), efficiently transmitted the disease to transgenic mice expressing ovine PrP, and that they shared unique biological and biochemical features upon propagation in mice.

*** These observations support the view that a truly infectious TSE agent, unrecognized until recently, infects sheep and goat flocks and may have important implications in terms of scrapie control and public health.


***The pathology features of Nor98 in the cerebellum of the affected sheep showed similarities with those of sporadic Creutzfeldt-Jakob disease in humans.


*** Intriguingly, these conclusions suggest that some pathological features of Nor98 are reminiscent of Gerstmann-Sträussler-Scheinker disease.

OR here;

*** The discovery of previously unrecognized prion diseases in both humans and animals (i.e., Nor98 in small ruminants) demonstrates that the range of prion diseases might be wider than expected and raises crucial questions about the epidemiology and strain properties of these new forms. We are investigating this latter issue by molecular and biological comparison of VPSPr, GSS and Nor98.


OR-10: Variably protease-sensitive prionopathy is transmissible in bank voles

Romolo Nonno,1 Michele Di Bari,1 Laura Pirisinu,1 Claudia D’Agostino,1 Stefano Marcon,1 Geraldina Riccardi,1 Gabriele Vaccari,1 Piero Parchi,2 Wenquan Zou,3 Pierluigi Gambetti,3 Umberto Agrimi1 1Istituto Superiore di Sanità; Rome, Italy; 2Dipartimento di Scienze Neurologiche, Università di Bologna; Bologna, Italy; 3Case Western Reserve University; Cleveland, OH USA

Background. Variably protease-sensitive prionopathy (VPSPr) is a recently described “sporadic”neurodegenerative disease involving prion protein aggregation, which has clinical similarities with non-Alzheimer dementias, such as fronto-temporal dementia. Currently, 30 cases of VPSPr have been reported in Europe and USA, of which 19 cases were homozygous for valine at codon 129 of the prion protein (VV), 8 were MV and 3 were MM. A distinctive feature of VPSPr is the electrophoretic pattern of PrPSc after digestion with proteinase K (PK). After PK-treatment, PrP from VPSPr forms a ladder-like electrophoretic pattern similar to that described in GSS cases. The clinical and pathological features of VPSPr raised the question of the correct classification of VPSPr among prion diseases or other forms of neurodegenerative disorders. Here we report preliminary data on the transmissibility and pathological features of VPSPr cases in bank voles.

Materials and Methods. Seven VPSPr cases were inoculated in two genetic lines of bank voles, carrying either methionine or isoleucine at codon 109 of the prion protein (named BvM109 and BvI109, respectively). Among the VPSPr cases selected, 2 were VV at PrP codon 129, 3 were MV and 2 were MM. Clinical diagnosis in voles was confirmed by brain pathological assessment and western blot for PK-resistant PrPSc (PrPres) with mAbs SAF32, SAF84, 12B2 and 9A2.

Results. To date, 2 VPSPr cases (1 MV and 1 MM) gave positive transmission in BvM109. Overall, 3 voles were positive with survival time between 290 and 588 d post inoculation (d.p.i.). All positive voles accumulated PrPres in the form of the typical PrP27–30, which was indistinguishable to that previously observed in BvM109 inoculated with sCJDMM1 cases.

In BvI109, 3 VPSPr cases (2 VV and 1 MM) showed positive transmission until now. Overall, 5 voles were positive with survival time between 281 and 596 d.p.i.. In contrast to what observed in BvM109, all BvI109 showed a GSS-like PrPSc electrophoretic pattern, characterized by low molecular weight PrPres. These PrPres fragments were positive with mAb 9A2 and 12B2, while being negative with SAF32 and SAF84, suggesting that they are cleaved at both the C-terminus and the N-terminus. Second passages are in progress from these first successful transmissions.

Conclusions. Preliminary results from transmission studies in bank voles strongly support the notion that VPSPr is a transmissible prion disease. Interestingly, VPSPr undergoes divergent evolution in the two genetic lines of voles, with sCJD-like features in BvM109 and GSS-like properties in BvI109.

The discovery of previously unrecognized prion diseases in both humans and animals (i.e., Nor98 in small ruminants) demonstrates that the range of prion diseases might be wider than expected and raises crucial questions about the epidemiology and strain properties of these new forms. We are investigating this latter issue by molecular and biological comparison of VPSPr, GSS and Nor98.

***> cattle, pigs, sheep, cwd, tse, prion, oh my! 

***> In contrast, cattle are highly susceptible to white-tailed deer CWD and mule deer CWD in experimental conditions but no natural CWD infections in cattle have been reported (Sigurdson, 2008; Hamir et al., 2006). 

Sheep and cattle may be exposed to CWD via common grazing areas with affected deer but so far, appear to be poorly susceptible to mule deer CWD (Sigurdson, 2008). In contrast, cattle are highly susceptible to white-tailed deer CWD and mule deer CWD in experimental conditions but no natural CWD infections in cattle have been reported (Sigurdson, 2008; Hamir et al., 2006). It is not known how susceptible humans are to CWD but given that the prion can be present in muscle, it is likely that humans have been exposed to the agent via consumption of venison (Sigurdson, 2008). Initial experimental research suggests that human susceptibility to CWD is low and there may be a robust species barrier for CWD transmission to humans (Sigurdson, 2008), however the risk appetite for a public health threat may still find this level unacceptable. 

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. 

BSE and Pigs

***> In summary, our results establish aerosols as a surprisingly efficient modality of prion transmission. This novel pathway of prion transmission is not only conceptually relevant for the field of prion research, but also highlights a hitherto unappreciated risk factor for laboratory personnel and personnel of the meat processing industry. In the light of these findings, it may be appropriate to revise current prion-related biosafety guidelines and health standards in diagnostic and scientific laboratories being potentially confronted with prion infected materials. While we did not investigate whether production of prion aerosols in nature suffices to cause horizontal prion transmission, the finding of prions in biological fluids such as saliva, urine and blood suggests that it may be worth testing this possibility in future studies.

Adriano Aguzzi ''We even showed that a prion AEROSOL will infect 100% of mice within 10 seconds of exposure''


Rabbits are not resistant to prion infection

Francesca Chianinia,1, Natalia Fernández-Borgesb,c,1, Enric Vidald , Louise Gibbarda , Belén Pintadoe , Jorge de Castroc , Suzette A. Priolaf , Scott Hamiltona , Samantha L. Eatona , Jeanie Finlaysona , Yvonne Panga , Philip Steelea , Hugh W. Reida , Mark P. Dagleisha , and Joaquín Castillab,c,g,2 a

Moredun Research Institute, Penicuik, Near Edinburgh EH26 0PZ, Scotland, United Kingdom; b CIC bioGUNE, Derio 48160, Bizkaia, Spain; g IKERBASQUE, Basque Foundation for Science, Bilbao 48011, Bizkaia, Spain; c Department of Infectology, Scripps Florida, Jupiter, FL 33458; f Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840; d Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain; and e Centro Nacional de Biotecnología (CNB), 28049 Cantoblanco, Madrid, Spain

Edited by Reed B. Wickner, National Institutes of Health, Bethesda, MD, and approved February 16, 2012 (received for review December 6, 2011)

The ability of prions to infect some species and not others is determined by the transmission barrier. This unexplained phenomenon has led to the belief that certain species were not susceptible to transmissible spongiform encephalopathies (TSEs) and therefore represented negligible risk to human health if consumed. Using the protein misfolding cyclic amplification (PMCA) technique, we were able to overcome the species barrier in rabbits, which have been classified as TSE resistant for four decades. Rabbit brain homogenate, either unseeded or seeded in vitro with disease-related prions obtained from different species, was subjected to serial rounds of PMCA. De novo rabbit prions produced in vitro from unseeded material were tested for infectivity in rabbits, with one of three intracerebrally challenged animals succumbing to disease at 766 d and displaying all of the characteristics of a TSE, thereby demonstrating that leporids are not resistant to prion infection. Material from the brain of the clinically affected rabbit containing abnormal prion protein resulted in a 100% attack rate after its inoculation in transgenic mice overexpressing rabbit PrP. Transmissibility to rabbits (>470 d) has been confirmed in 2 of 10 rabbits after intracerebral challenge. Despite rabbits no longer being able to be classified as resistant to TSEs, an outbreak of “mad rabbit disease” is unlikely.


In summary, after 3 y postchallenge with three different rabbitderived inocula, we have obtained one positive clinical case, one possible preclinical case, two intercurrent deaths, and six animals that have remained healthy. Although the incubation periods do not directly correlate with the degree of susceptibility, these data might indicate that rabbits are poorly susceptible to prion infection. Although the rabbits used in this study were not inbred, they all had identical full-length PrP sequences and, to date, no difference has been detected in the ORF PrP sequence in any other published rabbit PrP sequence placed in GenBank. To further investigate this, two types of second passage experiment were performed; three raPrPTg mice and 10 rabbits were all intracerebrally inoculated using brain homogenate from the clinically affected rabbit. In contrast to 100% of the de novo RaPrPSc-inoculated transgenic mice having succumbed to a standard clinical prion disease and thereby demonstrating a high rate of transmissibility in vivo, two of 10 rabbits developed a TSE (477 and 540 dpi, respectively) to date. A plausible explanation for the evident differences between these two transmission studies would be the high level of rabbit PrPC expression (4- to 6-fold) in the murine model. In addition, it is well known that even if overexpression does not increase susceptibility, it can significantly reduce the incubation time of disease (2). However, the two positive TSE cases in the second rabbit passage, even though 8 rabbits remained clinically normal at 560 dpi, have led us to conclude that rabbits can no longer be considered a prionresistant species. The long incubation times, even after a second passage, might be due to the presence of some unknown, and probably rare, susceptibility factor in rabbits, which may also be present, for example, in equids and canids.

To critically evaluate this risk, several experiments are currently underway to characterize this new prion disease in rabbits and other species to examine its ability to cross the species barrier. In addition, supplementary experiments have been initiated in rabbits and also in transgenic mice that overexpress rabbit PrPC, to evaluate their susceptibilities to other important prion diseases including CWD and BSE. There are several factors that any potential new TSE epidemic would require: (i) the new prion should be efficiently transmitted through the homologous species; (ii) animals should be edible by humans and should be slaughtered at an age at which the disease has developed, thereby increasing the chance that prions have replicated (especially for those prions that require long incubation times); and (iii) the meat and bone meal should be recycled and fed to new members of the same species. In the light of these data and taking into account the previous three factors, it is unlikely there will be an outbreak of “mad rabbit disease,” and consumers of rabbit meat face much less of a risk than consumers of cattle or sheep products.


Raccoons accumulate PrPSc after intracranial inoculation with the agents of chronic wasting disease (CWD) or transmissible mink encephalopathy (TME) but not atypical scrapie

Friday, December 14, 2012 

DEFRA U.K. What is the risk of Chronic Wasting Disease CWD being introduced into Great Britain? A Qualitative Risk Assessment October 2012 


In the USA, under the Food and Drug Administration's BSE Feed Regulation (21 CFR 589.2000) most material (exceptions include milk, tallow, and gelatin) from deer and elk is prohibited for use in feed for ruminant animals. With regards to feed for non-ruminant animals, under FDA law, CWD positive deer may not be used for any animal feed or feed ingredients. For elk and deer considered at high risk for CWD, the FDA recommends that these animals do not enter the animal feed system. However, this recommendation is guidance and not a requirement by law. Animals considered at high risk for CWD include: 

1) animals from areas declared to be endemic for CWD and/or to be CWD eradication zones and 

2) deer and elk that at some time during the 60-month period prior to slaughter were in a captive herd that contained a CWD-positive animal. 

Therefore, in the USA, materials from cervids other than CWD positive animals may be used in animal feed and feed ingredients for non-ruminants. 

The amount of animal PAP that is of deer and/or elk origin imported from the USA to GB can not be determined, however, as it is not specified in TRACES. 

It may constitute a small percentage of the 8412 kilos of non-fish origin processed animal proteins that were imported from US into GB in 2011. 

Overall, therefore, it is considered there is a __greater than negligible risk___ that (nonruminant) animal feed and pet food containing deer and/or elk protein is imported into GB. 

There is uncertainty associated with this estimate given the lack of data on the amount of deer and/or elk protein possibly being imported in these products. 


36% in 2007 (Almberg et al., 2011). In such areas, population declines of deer of up to 30 to 50% have been observed (Almberg et al., 2011). In areas of Colorado, the prevalence can be as high as 30% (EFSA, 2011). The clinical signs of CWD in affected adults are weight loss and behavioural changes that can span weeks or months (Williams, 2005). In addition, signs might include excessive salivation, behavioural alterations including a fixed stare and changes in interaction with other animals in the herd, and an altered stance (Williams, 2005). These signs are indistinguishable from cervids experimentally infected with bovine spongiform encephalopathy (BSE). Given this, if CWD was to be introduced into countries with BSE such as GB, for example, infected deer populations would need to be tested to differentiate if they were infected with CWD or BSE to minimise the risk of BSE entering the human food-chain via affected venison. snip..... The rate of transmission of CWD has been reported to be as high as 30% and can approach 100% among captive animals in endemic areas (Safar et al., 2008). 


In summary, in endemic areas, there is a medium probability that the soil and surrounding environment is contaminated with CWD prions and in a bioavailable form. In rural areas where CWD has not been reported and deer are present, there is a greater than negligible risk the soil is contaminated with CWD prion. snip..... In summary, given the volume of tourists, hunters and servicemen moving between GB and North America, the probability of at least one person travelling to/from a CWD affected area and, in doing so, contaminating their clothing, footwear and/or equipment prior to arriving in GB is greater than negligible... For deer hunters, specifically, the risk is likely to be greater given the increased contact with deer and their environment. However, there is significant uncertainty associated with these estimates. 


Therefore, it is considered that farmed and park deer may have a higher probability of exposure to CWD transferred to the environment than wild deer given the restricted habitat range and higher frequency of contact with tourists and returning GB residents. 



BSE TESTING (failed terribly and proven to be a sham) 

BSE SURVEILLANCE (failed terribly and proven to be a sham) 

BSE 589.2001 FEED REGULATIONS (another colossal failure, and proven to be a sham) 

these are facts folks. trump et al just admitted it with the feed ban. 


FDA Reports on VFD Compliance 

John Maday 

August 30, 2019 09:46 AM VFD-Form 007 (640x427) 

Before and after the current Veterinary Feed Directive rules took full effect in January, 2017, the FDA focused primarily on education and outreach. ( John Maday ) Before and after the current Veterinary Feed Directive (VFD) rules took full effect in January, 2017, the FDA focused primarily on education and outreach to help feed mills, veterinarians and producers understand and comply with the requirements. Since then, FDA has gradually increased the number of VFD inspections and initiated enforcement actions when necessary. On August 29, FDA released its first report on inspection and compliance activities. The report, titled “Summary Assessment of Veterinary Feed Directive Compliance Activities Conducted in Fiscal Years 2016 – 2018,” is available online.


***> FDA Reports on VFD Compliance 

TUESDAY, APRIL 18, 2017 




Docket No. APHIS-2018-0011 Chronic Wasting Disease Herd Certification Program Standards Singeltary

View Attachment:View as format pdf


Date: Fri, 18 Oct 2002 23:12:22 +0100 

From: Steve Dealler 

Reply-To: Bovine Spongiform Encephalopathy Organization: Netscape Online member 

To: BSE-L@ References: <3daf5023 .4080804="" wt.net="">

Dear Terry,

An excellent piece of review as this literature is desparately difficult to get back from Government sites.

What happened with the deer was that an association between deer meat eating and sporadic CJD was found in about 1993. The evidence was not great but did not disappear after several years of asking CJD cases what they had eaten. I think that the work into deer disease largely stopped because it was not helpful to the UK industry...and no specific cases were reported. Well, if you dont look adequately like they are in USA currenly then you wont find any!

Steve Dealler 


Stephen Dealler is a consultant medical microbiologist deal@airtime.co.uk 

BSE Inquiry Steve Dealler

Management In Confidence

BSE: Private Submission of Bovine Brain Dealler

snip...see full text;




1996-12-04: BBC - Horizon BSE1 - BSE2 The Invisible Enemy, The British Disease, CWD, sporadic CJD

Mad Camel Disease CPD TSE Prion dromedary camels (Camelus dromedarius) is spreading

In 2018 prion disease was detected in camels at an abattoir in Algeria for the first time. 

Prion disease has recently been confirmed in three dromedary camels (Camelus dromedarius) from an Algerian slaughterhouse (Babelhadj et al., 2018) after clinical signs compatible with those of TSEs in other species were observed ante mortem. Disease associated pathological changes or prion protein were found in brain by Western blotting, histology, immunohistochemistry (IHC) and paraffin-embedded tissue blot; PrPSc was also detected in the lymph nodes of the one camel tested by IHC.

Information gathered from breeders and slaughterhouse personnel suggests that similar clinical signs had been observed since the 1980s (Babelhadj et al., 2018). Subsequently, the disease has also been reported in a single case of a 12 year old dromedary camel from the region of Tataouine, Tunisia (Agrimi, 2019; OIE bulletin 2019). 

There are many knowledge gaps about the biological characteristics of this new TSE, termed camel prion disease (CPD). Detection of infection in lymph nodes of one animal suggests extra-neural pathogenesis and, therefore, potential transmission of CPD between animals similar to that of classical scrapie and CWD. Such transmission of CPD could be facilitated over long distances by the traditional nomadic herding practices of dromedaries and the trade patterns between Algeria and other countries in North Africa and the Middle East (Bouslikhane, 2015). In light of the devastation caused by BSE, and its subsequent zoonotic transmission, CPD was used here to assess the probability of entry of a novel prion disease agent into the UK via livestock and livestock products. The approach used was to assess the aggregated probability, using the number of imports per year to avoid potential under-estimation as has previously been described (Kelly et al., 2018). Of note, the zoonotic potential of the disease is unknown and this assessment is of the probability of introduction of the CPD agent into the UK only, not of any onward transmission to humans or animals. 


3. Results

3.1. Risk assessment

3.1.1. Probability camel is infected with camel prion disease in exporting country (p1)

Detection of abnormal neurological signs since the 1980s within a restricted geographical area of Algeria suggests that the expansion of CPD to other areas (and countries) may be restricted or that the disease can remain largely undiagnosed. According to a recent presentation of the Mediterranean Animal Health Network, the disease was also reported in Tunisia and the incidence in the initial region of Algeria was described as ‘rapidly and progressively increasing’ (Agrimi, 2019). It is, therefore, possible that movement of camels has allowed infected animals to enter other countries. Asides from the legal trade of camels, approximately 268 million people in Africa practice some form of pastoralism (Luizza, 2017). For example, over 95% of cross-border trade within the Horn of Africa is unofficial and carried out by nomadic pastoralists trading livestock. Given that disease was first noticed in the 1980s and the nomadic way of life in this area, exporting countries were therefore considered as those making up the regions of North Africa and the Middle East for the purpose of this assessment.

Twenty of 937 camels in 2015 and 51 of 1,322 in 2016 showed neurologic signs at slaughter giving an overall estimated apparent prevalence of 3.1% in dromedaries brought for slaughter (Babelhadj et al., 2018). In the absence of further information including confirmatory testing, an assumption was made that the prevalence of CPD in live camels in the regions of interest was high with high uncertainty because of the lack of testing data from countries other than Algeria and in only 3 camels in Algeria itself.

see full report;

Assessing the aggregated probability of entry of a novel prion disease agent into the United Kingdom

Monday, September 14, 2020 

Assessing the aggregated probability of entry of a novel prion disease agent into the United Kingdom



Subject: Prion Disease in Dromedary Camels, Algeria

Our identification of this prion disease in a geographically widespread livestock species requires urgent enforcement of surveillance and assessment of the potential risks to human and animal health.

Wednesday, May 30, 2018 

Dromedary camels in northern Africa have a neurodegenerative prion disease that may have originated decades ago



Saturday, April 14, 2018

Dromedary Camels Algeria Prion (Mad Camel Disease) TSE BSE MRR Import Export Risk Factors Excluding Grains and Plants

Dromedary Camels Algeria Prion (Mad Camel Disease) TSE BSE MRR Import Export Risk Factors Excluding Grains and Plants

(Grains and Plants Materials Could Harbor the Transmissible Spongiform Encephalopathy TSE Prion agent...TSS)

Dromedary Camels Algeria Prion (Mad Camel Disease) TSE BSE MRR Import Export Risk Factors Excluding Grains and Plants


Review: Update on Classical and Atypical Scrapie in Sheep and Goats


APHIS USDA MORE SCRAPIE ATYPICAL Nor-98 Confirmed USA September 15 2020

TUESDAY, JUNE 30, 2020 

National Scrapie Eradication Program May 2020 Monthly Report Fiscal Year 2020 U.S. Department of Agriculture Animal and Plant Health Inspection Service Veterinary Services Strategy and Policy, Ruminant Health Center Small Ruminant Health June 15, 2020

2.3.2. New evidence on the zoonotic potential of atypical BSE and atypical scrapie prion strains


2.3.2. New evidence on the zoonotic potential of atypical BSE and atypical scrapie prion strains

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. 


***> EFSA Annual report of the Scientific Network on BSE-TSE 2020 Singeltary Submission


Bovine adapted transmissible mink encephalopathy is similar to L-BSE after passage through sheep with the VRQ/VRQ genotype but not VRQ/ARQ 


The emergence of classical BSE from atypical/ Nor98 scrapie


Scrapie TSE Prion Zoonosis Zoonotic, what if?

Saturday, April 23, 2016


Saturday, April 23, 2016

SCRAPIE WS-01: Prion diseases in animals and zoonotic potential 2016

Prion. 10:S15-S21. 2016 ISSN: 1933-6896 printl 1933-690X online

Taylor & Francis

Prion 2016 Animal Prion Disease Workshop Abstracts

WS-01: Prion diseases in animals and zoonotic potential

Juan Maria Torres a, Olivier Andreoletti b, J uan-Carlos Espinosa a. Vincent Beringue c. Patricia Aguilar a,

Natalia Fernandez-Borges a. and Alba Marin-Moreno a

"Centro de Investigacion en Sanidad Animal ( CISA-INIA ). Valdeolmos, Madrid. Spain; b UMR INRA -ENVT 1225 Interactions Holes Agents Pathogenes. ENVT. Toulouse. France: "UR892. Virologie lmmunologie MolécuIaires, Jouy-en-Josas. France

Dietary exposure to bovine spongiform encephalopathy (BSE) contaminated bovine tissues is considered as the origin of variant Creutzfeldt Jakob (vCJD) disease in human. To date, BSE agent is the only recognized zoonotic prion. Despite the variety of Transmissible Spongiform Encephalopathy (TSE) agents that have been circulating for centuries in farmed ruminants there is no apparent epidemiological link between exposure to ruminant products and the occurrence of other form of TSE in human like sporadic Creutzfeldt Jakob Disease (sCJD). However, the zoonotic potential of the diversity of circulating TSE agents has never been systematically assessed. The major issue in experimental assessment of TSEs zoonotic potential lies in the modeling of the ‘species barrier‘, the biological phenomenon that limits TSE agents’ propagation from a species to another. In the last decade, mice genetically engineered to express normal forms of the human prion protein has proved essential in studying human prions pathogenesis and modeling the capacity of TSEs to cross the human species barrier.

To assess the zoonotic potential of prions circulating in farmed ruminants, we study their transmission ability in transgenic mice expressing human PrPC (HuPrP-Tg). Two lines of mice expressing different forms of the human PrPC (129Met or 129Val) are used to determine the role of the Met129Val dimorphism in susceptibility/resistance to the different agents.

These transmission experiments confirm the ability of BSE prions to propagate in 129M- HuPrP-Tg mice and demonstrate that Met129 homozygotes may be susceptible to BSE in sheep or goat to a greater degree than the BSE agent in cattle and that these agents can convey molecular properties and neuropathological indistinguishable from vCJD. However homozygous 129V mice are resistant to all tested BSE derived prions independently of the originating species suggesting a higher transmission barrier for 129V-PrP variant.

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.


Title: Transmission of scrapie prions to primate after an extended silent incubation period 


item COMOY, EMMANUEL - French Atomic Energy Commission item MIKOL, JACQUELINE - French Atomic Energy Commission item LUCCANTONI-FREIRE, SOPHIE - French Atomic Energy Commission item CORREIA, EVELYNE - French Atomic Energy Commission item LESCOUTRA-ETCHEGARAY, NATHALIE - French Atomic Energy Commission item DURAND, VALÉRIE - French Atomic Energy Commission item DEHEN, CAPUCINE - French Atomic Energy Commission item ANDREOLETTI, OLIVIER - Institut National De La Recherche Agronomique (INRA) item CASALONE, CRISTINA - Instituto Zooprofilattico Sperimentale Del Mazzogiorno item Richt, Juergen item Greenlee, Justin item BARON, THIERRY - French Agency For Food, Environmental And Occupational Health & Safety (ANSES) item BENESTAD, SYLVIE - National Veterinary Institute - Norway item HILLS, BOB - Health Canada item BROWN, PAUL - French Atomic Energy Commission item DESLYS, JEAN-PHILIPPE - French Atomic Energy Commission

Submitted to: Scientific Reports 

Publication Type: Peer Reviewed Journal 

Publication Acceptance Date: 5/28/2015 

Publication Date: 6/30/2015 

Citation: Comoy, E.E., Mikol, J., Luccantoni-Freire, S., Correia, E., Lescoutra-Etchegaray, N., Durand, V., Dehen, C., Andreoletti, O., Casalone, C., Richt, J.A., Greenlee, J.J., Baron, T., Benestad, S., Brown, P., Deslys, J. 2015. Transmission of scrapie prions to primate after an extended silent incubation period. Scientific Reports. 5:11573.

Interpretive Summary: The transmissible spongiform encephalopathies (also called prion diseases) are fatal neurodegenerative diseases that affect animals and humans. The agent of prion diseases is a misfolded form of the prion protein that is resistant to breakdown by the host cells. Since all mammals express prion protein on the surface of various cells such as neurons, all mammals are, in theory, capable of replicating prion diseases. One example of a prion disease, bovine spongiform encephalopathy (BSE; also called mad cow disease), has been shown to infect cattle, sheep, exotic undulates, cats, non-human primates, and humans when the new host is exposed to feeds or foods contaminated with the disease agent. The purpose of this study was to test whether non-human primates (cynomologous macaque) are susceptible to the agent of sheep scrapie. After an incubation period of approximately 10 years a macaque developed progressive clinical signs suggestive of neurologic disease. Upon postmortem examination and microscopic examination of tissues, there was a widespread distribution of lesions consistent with a transmissible spongiform encephalopathy. 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.

*** 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.

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 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. 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***


***our findings suggest that possible transmission risk of H-type BSE to sheep and human. Bioassay will be required to determine whether the PMCA products are infectious to these animals.


***> 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. <***

Transmission of scrapie prions to primate after an extended silent incubation period 

Emmanuel E. Comoy, Jacqueline Mikol, Sophie Luccantoni-Freire, Evelyne Correia, Nathalie Lescoutra-Etchegaray, Valérie Durand, Capucine Dehen, Olivier Andreoletti, Cristina Casalone, Juergen A. Richt, Justin J. Greenlee, Thierry Baron, Sylvie L. Benestad, Paul Brown & Jean-Philippe Deslys Scientific Reports volume 5, Article number: 11573 (2015) | Download Citation


Classical bovine spongiform encephalopathy (c-BSE) is the only animal prion disease reputed to be zoonotic, causing variant Creutzfeldt-Jakob disease (vCJD) in humans and having guided protective measures for animal and human health against animal prion diseases. Recently, partial transmissions to humanized mice showed that the zoonotic potential of scrapie might be similar to c-BSE. We here report the direct transmission of a natural classical scrapie isolate to cynomolgus macaque, a highly relevant model for human prion diseases, after a 10-year silent incubation period, with features similar to those reported for human cases of sporadic CJD. Scrapie is thus actually transmissible to primates with incubation periods compatible with their life expectancy, although fourfold longer than BSE. Long-term experimental transmission studies are necessary to better assess the zoonotic potential of other prion diseases with high prevalence, notably Chronic Wasting Disease of deer and elk and atypical/Nor98 scrapie.


Discussion We describe the transmission of spongiform encephalopathy in a non-human primate inoculated 10 years earlier with a strain of sheep c-scrapie. Because of this extended incubation period in a facility in which other prion diseases are under study, we are obliged to consider two alternative possibilities that might explain its occurrence. We first considered the possibility of a sporadic origin (like CJD in humans). Such an event is extremely improbable because the inoculated animal was 14 years old when the clinical signs appeared, i.e. about 40% through the expected natural lifetime of this species, compared to a peak age incidence of 60–65 years in human sporadic CJD, or about 80% through their expected lifetimes. 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.

The second possibility is a laboratory cross-contamination. Three facts make this possibility equally unlikely. First, handling of specimens in our laboratory is performed with fastidious attention to the avoidance of any such cross-contamination. Second, no laboratory cross-contamination has ever been documented in other primate laboratories, including the NIH, even between infected and uninfected animals housed in the same or adjacent cages with daily intimate contact (P. Brown, personal communication). Third, the cerebral lesion profile is different from all the other prion diseases we have studied in this model19, with a correlation between cerebellar lesions (massive spongiform change of Purkinje cells, intense PrPres staining and reactive gliosis26) and ataxia. The iron deposits present in the globus pallidus are a non specific finding that have been reported previously in neurodegenerative diseases and aging27. Conversely, the thalamic lesion was reminiscent of a metabolic disease due to thiamine deficiency28 but blood thiamine levels were within normal limits (data not shown). The preferential distribution of spongiform change in cortex associated with a limited distribution in the brainstem is reminiscent of the lesion profile in MM2c and VV1 sCJD patients29, but interspecies comparison of lesion profiles should be interpreted with caution. It is of note that the same classical scrapie isolate induced TSE in C57Bl/6 mice with similar incubation periods and lesional profiles as a sample derived from a MM1 sCJD patient30.

We are therefore confident that the illness in this cynomolgus macaque represents a true transmission of a sheep c-scrapie isolate directly to an old-world monkey, which taxonomically resides in the primate subdivision (parvorder of catarrhini) that includes humans. With an homology of its PrP protein with humans of 96.4%31, cynomolgus macaque constitutes a highly relevant model for assessing zoonotic risk of prion diseases. Since our initial aim was to show the absence of transmission of scrapie to macaques in the worst-case scenario, we obtained materials from a flock of naturally-infected sheep, affecting animals with different genotypes32. This c-scrapie isolate exhibited complete transmission in ARQ/ARQ sheep (332 ± 56 days) and Tg338 transgenic mice expressing ovine VRQ/VRQ prion protein (220 ± 5 days) (O. Andreoletti, personal communication). From the standpoint of zoonotic risk, it is important to note that sheep with c-scrapie (including the isolate used in our study) have demonstrable infectivity throughout their lymphoreticular system early in the incubation period of the disease (3 months-old for all the lymphoid organs, and as early as 2 months-old in gut-associated lymph nodes)33. In addition, scrapie infectivity has been identified in blood34, milk35 and skeletal muscle36 from asymptomatic but scrapie infected small ruminants which implies a potential dietary exposure for consumers.

Two earlier studies have reported the occurrence of clinical TSE in cynomolgus macaques after exposures to scrapie isolates. In the first study, the “Compton” scrapie isolate (derived from an English sheep) and serially propagated for 9 passages in goats did not transmit TSE in cynomolgus macaque, rhesus macaque or chimpanzee within 7 years following intracerebral challenge1; conversely, after 8 supplementary passages in conventional mice, this “Compton” isolate induced TSE in a cynomolgus macaque 5 years after intracerebral challenge, but rhesus macaques and chimpanzee remained asymptomatic 8.5 years post-exposure8. However, multiple successive passages that are classically used to select laboratory-adapted prion strains can significantly modify the initial properties of a scrapie isolate, thus questioning the relevance of zoonotic potential for the initial sheep-derived isolate. The same isolate had also induced disease into squirrel monkeys (new-world monkey)9. A second historical observation reported that a cynomolgus macaque developed TSE 6 years post-inoculation with brain homogenate from a scrapie-infected Suffolk ewe (derived from USA), whereas a rhesus macaque and a chimpanzee exposed to the same inoculum remained healthy 9 years post-exposure1. This inoculum also induced TSE in squirrel monkeys after 4 passages in mice. Other scrapie transmission attempts in macaque failed but had more shorter periods of observation in comparison to the current study. Further, it is possible that there are differences in the zoonotic potential of different scrapie strains.

The most striking observation in our study is the extended incubation period of scrapie in the macaque model, which has several implications. Firstly, our observations constitute experimental evidence in favor of the zoonotic potential of c-scrapie, at least for this isolate that has been extensively studied32,33,34,35,36. The cross-species zoonotic ability of this isolate should be confirmed by performing duplicate intracerebral exposures and assessing the transmissibility by the oral route (a successful transmission of prion strains through the intracerebral route may not necessarily indicate the potential for oral transmission37). However, such confirmatory experiments may require more than one decade, which is hardly compatible with current general management and support of scientific projects; thus this study should be rather considered as a case report.

Secondly, transmission of c-BSE to primates occurred within 8 years post exposure for the lowest doses able to transmit the disease (the survival period after inoculation is inversely proportional to the initial amount of infectious inoculum). The occurrence of scrapie 10 years after exposure to a high dose (25 mg) of scrapie-infected sheep brain suggests that the macaque has a higher species barrier for sheep c-scrapie than c-BSE, although it is notable that previous studies based on in vitro conversion of PrP suggested that BSE and scrapie prions would have a similar conversion potential for human PrP38.

Thirdly, prion diseases typically have longer incubation periods after oral exposure than after intracerebral inoculations: since humans can develop Kuru 47 years after oral exposure39, an incubation time of several decades after oral exposure to scrapie would therefore be expected, leading the disease to occur in older adults, i.e. the peak age for cases considered to be sporadic disease, and making a distinction between scrapie-associated and truly sporadic disease extremely difficult to appreciate.

Fourthly, epidemiologic evidence is necessary to confirm the zoonotic potential of an animal disease suggested by experimental studies. A relatively short incubation period and a peculiar epidemiological situation (e.g., all the first vCJD cases occurring in the country with the most important ongoing c-BSE epizootic) led to a high degree of suspicion that c-BSE was the cause of vCJD. Sporadic CJD are considered spontaneous diseases with an almost stable and constant worldwide prevalence (0.5–2 cases per million inhabitants per year), and previous epidemiological studies were unable to draw a link between sCJD and classical scrapie6,7,40,41, even though external causes were hypothesized to explain the occurrence of some sCJD clusters42,43,44. However, extended incubation periods exceeding several decades would impair the predictive values of epidemiological surveillance for prion diseases, already weakened by a limited prevalence of prion diseases and the multiplicity of isolates gathered under the phenotypes of “scrapie” and “sporadic CJD”.

Fifthly, considering this 10 year-long incubation period, together with both laboratory and epidemiological evidence of decade or longer intervals between infection and clinical onset of disease, no premature conclusions should be drawn from negative transmission studies in cynomolgus macaques with less than a decade of observation, as in the aforementioned historical transmission studies of scrapie to primates1,8,9. Our observations and those of others45,46 to date are unable to provide definitive evidence regarding the zoonotic potential of CWD, atypical/Nor98 scrapie or H-type BSE. The extended incubation period of the scrapie-affected macaque in the current study also underscores the limitations of rodent models expressing human PrP for assessing the zoonotic potential of some prion diseases since their lifespan remains limited to approximately two years21,47,48. This point is illustrated by the fact that the recently reported transmission of scrapie to humanized mice was not associated with clinical signs for up to 750 days and occurred in an extreme minority of mice with only a marginal increase in attack rate upon second passage13. The low attack rate in these studies is certainly linked to the limited lifespan of mice compared to the very long periods of observation necessary to demonstrate the development of scrapie. Alternatively, one could estimate that a successful second passage is the result of strain adaptation to the species barrier, thus poorly relevant of the real zoonotic potential of the original scrapie isolate of sheep origin49. The development of scrapie in this primate after an incubation period compatible with its lifespan complements the study conducted in transgenic (humanized) mice; taken together these studies suggest that some isolates of sheep scrapie can promote misfolding of the human prion protein and that scrapie can develop within the lifespan of some primate species.

In addition to previous studies on scrapie transmission to primate1,8,9 and the recently published study on transgenic humanized mice13, our results constitute new evidence for recommending that the potential risk of scrapie for human health should not be dismissed. Indeed, human PrP transgenic mice and primates are the most relevant models for investigating the human transmission barrier. To what extent such models are informative for measuring the zoonotic potential of an animal TSE under field exposure conditions is unknown. During the past decades, many protective measures have been successfully implemented to protect cattle from the spread of c-BSE, and some of these measures have been extended to sheep and goats to protect from scrapie according to the principle of precaution. Since cases of c-BSE have greatly reduced in number, those protective measures are currently being challenged and relaxed in the absence of other known zoonotic animal prion disease. We recommend that risk managers should be aware of the long term potential risk to human health of at least certain scrapie isolates, notably for lymphotropic strains like the classical scrapie strain used in the current study. Relatively high amounts of infectivity in peripheral lymphoid organs in animals infected with these strains could lead to contamination of food products produced for human consumption. Efforts should also be maintained to further assess the zoonotic potential of other animal prion strains in long-term studies, notably lymphotropic strains with high prevalence like CWD, which is spreading across North America, and atypical/Nor98 scrapie (Nor98)50 that was first detected in the past two decades and now represents approximately half of all reported cases of prion diseases in small ruminants worldwide, including territories previously considered as scrapie free... 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.

***> 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. <***

Like lambs to the slaughter 

* 31 March 2001 * 

Debora MacKenzie * 

Magazine issue 2284 

Suspect symptoms 

What if you can catch old-fashioned CJD by eating meat from a sheep infected with scrapie? 

Exclusive from New Scientist magazine 

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. 

Photo: Murdo McLeod 

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. 

Brain damage 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. Multiple strains "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," she says. 

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. 

Deformed proteins 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. 

More at: Proceedings of the National Academy of Sciences (vol 98, p 4142) 

Correspondence about this story should be directed to letters@newscientist.com 1900 GMT, 28 March 2001 

* New Scientist 

2001 Mar 27;98(7):4142-7. doi: 10.1073/pnas.041490898. Epub 2001 Mar 20.

Adaptation of the bovine spongiform encephalopathy agent to primates and comparison with Creutzfeldt-- Jakob disease: implications for human health

C I Lasmézas 1, J G Fournier, V Nouvel, H Boe, D Marcé, F Lamoury, N Kopp, J J Hauw, J Ironside, M Bruce, D Dormont, J P Deslys

Affiliations expand

PMID: 11259641 PMCID: PMC31193 DOI: 10.1073/pnas.041490898


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.


We found that the BSE agent in nonhuman primates is similar to that causing vCJD in humans and tends to evolve rapidly toward a primate-adapted variant. Furthermore, we showed that the strain responsible for iCJD is closely related to that of one patient with sCJD, and, more unexpectedly, that these agents were similar to the French scrapie strain studied (but different from the U.S. scrapie strain). This finding requires a cautious interpretation for several reasons, not least because of the inevitably limited number of TSE strains that can be studied by such a cumbersome method as strain typing. Nonetheless, it also prompts reconsideration of the possibility that, in some instances, sheep and human TSEs can share a common origin. 

why do we not want to do TSE transmission studies on chimpanzees $

5. A positive result from a chimpanzee challenged severly would likely create alarm in some circles even if the result could not be interpreted for man. 

I have a view that all these agents could be transmitted provided a large enough dose by appropriate routes was given and the animals kept long enough. 

Until the mechanisms of the species barrier are more clearly understood it might be best to retain that hypothesis.




Chronic Wasting Disease CWD TSE Prion Cervid State by State and Global Update November 2020

Terry S. Singeltary Sr.