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Walter Bodemer German Primate Center, Kellnerweg 4, 37077 Göttingen, Germany Correspondence to: Walter Bodemer (firstname.lastname@example.org
Received: 15 June 2016 – Revised: 24 August 2016 – Accepted: 30 August 2016 – Published: 7 September 2016
Prions gained widespread public and scientiﬁc interest in the year 2000. At that time, the human neurological Creutzfeldt–Jakob disease (CJD) was known. However, new CJD cases were diagnosed but they could not be ascribed to one of the classical CJD categories i.e. sporadic (sCJD), hereditary or acquired. Hence, they were classiﬁed as variant CJD (vCJD). Later on, experimental evidence suggested that vCJD was caused by prions postulated as unique novel infectious agents and, for example, responsible for bovine spongiform encephalopathy (BSE) also known as mad cow disease. The infection of humans by transmission of BSE prions also deﬁned vCJD as a zoonotic disease. Prions, especially those associated with scrapie in sheep had been known for quite some time and misleadingly discussed as a slow virus. Therefore, this enigmatic pathogen and the transmission of this unusual infectious agent was a matter of a controversial scientiﬁc debate. An agent without nucleic acid did not follow the current dogma postulating DNA or RNA as inheritable information encoding molecules. Although numerous experimental results clearly demonstrated the infectious capacity of prions in several animal species, a model close to human was not readily available. Therefore, the use of rhesus monkeys (Macaca mulatta) served as a non-human primate model to elucidate prion infection under controlled experimental conditions. Not the least, transmission of BSE, human vCJD, and sCJD prions could be conﬁrmed in our study. Any prion infection concomitant with progression of disease in humans, especially vCJD, could be analyzed only retrospectively and at late stages of disease. In contrast, the prion-infected rhesus monkeys were accessible before and after infection; the progression from early stage to late clinical stages – and eventually death of the animal–could be traced. Because of the phylogenetic proximity to humans, the rhesus monkey was superior to any rodent or other animal model. For these reasons an experimental approach had been conceived by J. Collinge in London and A. Aguzzi in Zurich and performed in a cooperative study with both research groups in the pathology unit of the German Primate Center (DPZ). The study in the DPZ lasted from 2001 until 2012. Our research in the pathology unit provided a temporal monitoring of how an initial prion infection develops eventually into disease; an approach that would have never been possible in humans since the time point of infection with prions from, for example, BSE is always unknown. Telemetry revealed a shift in sleep– wake cycles early on, long before behavioral changes or clinical symptoms appeared. Pathology conﬁrmed nonneuronal tissue as hidden places where prions exist. The rhesus model also allowed ﬁrst comparative studies of epigenetic modiﬁcations on RNA in peripheral blood and brain tissue collected from uninfected and prion infected animals. To conclude, our studies clearly demonstrated that this model is valid since progression to disease is almost identical to human CJD.
Published by Copernicus Publications on behalf of the Deutsches Primatenzentrum GmbH (DPZ).
2 Methods and results
2.1 Animals The reason to perform prion research in rhesus monkeys was to monitor infection and the temporal progression of prion infection in the rhesus monkey. In contrast to studies of human CJD cases, we could decide on the infectious dose. We also could control behavior immediately after prion inoculation and during the rather long time until animals died from the prion infection. Hidden places where prions might exist were found. Even epigenetic modiﬁcations on RNA could be detected. Taken together, these experimental approaches depended on animals. Using rhesus monkeys as a model system required thorough ethic reasoning and consultation with authorities before we actually turned to conduct the experiments. The Number of animals was limited just to fulﬁll statistical conditions. The individual health status was obtained and health care was provided throughout the study. The animals underwent daily inspection to monitor any changes in health and behavior. The experiments were conceived with the aim of reducing pain, suffering, and harm. Groups of animals were preferred in order to keep them in a social environment. The animals were originally kept in Vienna at Baxter and transferred to the German Primate Center (DPZ) in 2001. J. Collinge, A. Aguzzi, and C. Weissmann were the scientists who recommended this well-controlled prion infection study, and ﬁnancial support was provided by an EU grant.To ensure statistical signiﬁcance four groups consisting of four rhesus macaques each were formed: one uninfected control group, one group infected with BSE prions, one with vCJD prions, and one with sCJD prions. Health of animals, infection, and progression to disease was looked at in our pathology department and in cooperation with W. Schulz-Schaeffer at the UMG (University Medicine, Göttingen). Besides, neurologists from the UMG also observed the animals whenever clinical symptoms seemed to appear. This close observation and comparison with human CJD cases demonstrated how close clinical progression of human disease resembles the experimental infection in the non-human primate.
2.2 Infection Infectious prions from brain tissue of one sCJD and one vCJD case (provided by J. Collinge) as well as BSE prions (from a “German” madcow case and provided by W. Schulz Schaeffer) were intraperitoneally administered into the rhesus monkeys.
2.3 Monitoring of behavior and telemetry Early behavioral monitoring was carried out by the ethologists I. Machatschke and J. Dittami from Vienna University. Transmitters were used to record changes in the circadian rhythms. Body temperature, sleep–wake cycles, and activity proﬁles could be obtained over a time span of 2 years. Up to half a year after infection animals did not show any signs of prion infection. However, after 6 months and persisting for another few months some animals had some disturbances in circadian rhythms which disappeared and then never appeared again(I. Machatschke, personal communication,2006).For a rather long time of about 4–5 years animals seemed to be healthy. But then, almost all animals rapidly progressed to symptoms. Symptoms were highly similar or even identical to those seen in human CJD.
2.4 Pathology Blood and necropsy specimens from the animals served as a valuable source to detect pathologically associated prion protein even in non-neuronal skeletal and cardiac tissue. These “hidden places” of prion pathology and replication were clearly demonstrated and extended our view where prions might spread within an organism. Not only leukocytes and neuronal tissue harbor abnormal prion protein isoforms but also other tissues can propagate prion protein isoforms leading to toxicity, cell degeneration, and eventually transmissible prions (Krasemann et al., 2010, 2013).
Most importantly, early signs of an altered circadian rhythm, sleep–wake cycle, and activity and body temperature were recorded in prion-infected animals. This experimental approach would have never been feasible in studies with human CJD cases. After 4–6 years animals developed clinical symptoms highly similar to those typical for CJD. Clinicians conﬁrmed how close the animal model and the human disease matched. Non-neuronal tissue like cardiac muscle and peripheral blood with abnormal, disease-related prion protein were detected in rhesus monkey tissues.
Molecular changes in RNA from repetitive Alu and BC200 DNA elements were identiﬁed and found to be targets of epigenetic editing mechanisms active in prion disease. To conclude, our results with the rhesus monkey model for prion disease proved to be a valid model and increased our knowledge of pathogenic processes that are distinctive to prion disease.
SEE FULL TEXT ;
*** WDA 2016 NEW YORK ***
We found that CWD adapts to a new host more readily than BSE and that human PrP was unexpectedly prone to misfolding by CWD prions. In addition, we investigated the role of specific regions of the bovine, deer and human PrP protein in resistance to conversion by prions from another species. We have concluded that the human protein has a region that confers unusual susceptibility to conversion by CWD prions.
Student Presentations Session 2
The species barriers and public health threat of CWD and BSE prions
Ms. Kristen Davenport1, Dr. Davin Henderson1, Dr. Candace Mathiason1, Dr. Edward Hoover1 1Colorado State University
Chronic wasting disease (CWD) is spreading rapidly through cervid populations in the USA. Bovine spongiform encephalopathy (BSE, mad cow disease) arose in the 1980s because cattle were fed recycled animal protein. These and other prion diseases are caused by abnormal folding of the normal prion protein (PrP) into a disease causing form (PrPd), which is pathogenic to nervous system cells and can cause subsequent PrP to misfold. CWD spreads among cervids very efficiently, but it has not yet infected humans. On the other hand, BSE was spread only when cattle consumed infected bovine or ovine tissue, but did infect humans and other species. The objective of this research is to understand the role of PrP structure in cross-species infection by CWD and BSE. To study the propensity of each species’ PrP to be induced to misfold by the presence of PrPd from verious species, we have used an in vitro system that permits detection of PrPd in real-time. We measured the conversion efficiency of various combinations of PrPd seeds and PrP substrate combinations. We observed the cross-species behavior of CWD and BSE, in addition to feline-adapted CWD and BSE. We found that CWD adapts to a new host more readily than BSE and that human PrP was unexpectedly prone to misfolding by CWD prions. In addition, we investigated the role of specific regions of the bovine, deer and human PrP protein in resistance to conversion by prions from another species. We have concluded that the human protein has a region that confers unusual susceptibility to conversion by CWD prions. CWD is unique among prion diseases in its rapid spread in natural populations. BSE prions are essentially unaltered upon passage to a new species, while CWD adapts to the new species. This adaptation has consequences for surveillance of humans exposed to CWD.
Wildlife Disease Risk Communication Research Contributes to Wildlife Trust Administration Exploring perceptions about chronic wasting disease risks among wildlife and agriculture professionals and stakeholders
PRION 2016 TOKYO
Zoonotic Potential of CWD Prions: An Update
Ignazio Cali1, Liuting Qing1, Jue Yuan1, Shenghai Huang2, Diane Kofskey1,3, Nicholas Maurer1, Debbie McKenzie4, Jiri Safar1,3,5, Wenquan Zou1,3,5,6, Pierluigi Gambetti1, Qingzhong Kong1,5,6 1Department of Pathology, 3National Prion Disease Pathology Surveillance Center, 5Department of Neurology, 6National Center for Regenerative Medicine, Case Western Reserve University, Cleveland, OH 44106, USA. 4Department of Biological Sciences and Center for Prions and Protein Folding Diseases, University of Alberta, Edmonton, Alberta, Canada, 2Encore Health Resources, 1331 Lamar St, Houston, TX 77010
Chronic wasting disease (CWD) is a widespread and highly transmissible prion disease in free-ranging and captive cervid species in North America. The zoonotic potential of CWD prions is a serious public health concern, but the susceptibility of human CNS and peripheral organs to CWD prions remains largely unresolved. We reported earlier that peripheral and CNS infections were detected in transgenic mice expressing human PrP129M or PrP129V. Here we will present an update on this project, including evidence for strain dependence and influence of cervid PrP polymorphisms on CWD zoonosis as well as the characteristics of experimental human CWD prions.
PRION 2016 TOKYO In Conjunction with Asia Pacific Prion Symposium 2016 PRION 2016 Tokyo Prion 2016
Monday, May 02, 2016
*** Zoonotic Potential of CWD Prions: An Update Prion 2016 Tokyo ***
Saturday, April 23, 2016
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 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 ef?ciency comparable to that of cattle BSE. While the ef?ciency 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.
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.
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.
SCRAPIE WS-01: Prion diseases in animals and zoonotic potential 2016
Prion. 10:S15-S21. 2016 ISSN: 1933-6896 printl 1933-690X online
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.
LOOKING FOR CWD IN HUMANS AS nvCJD or as an ATYPICAL CJD, LOOKING IN ALL THE WRONG PLACES $$$
*** These results would seem to suggest that CWD does indeed have zoonotic potential, at least as judged by the compatibility of CWD prions and their human PrPC target. Furthermore, extrapolation from this simple in vitro assay suggests that if zoonotic CWD occurred, it would most likely effect those of the PRNP codon 129-MM genotype and that the PrPres type would be similar to that found in the most common subtype of sCJD (MM1).***
*** The potential impact of prion diseases on human health was greatly magnified by the recognition that interspecies transfer of BSE to humans by beef ingestion resulted in vCJD. While changes in animal feed constituents and slaughter practices appear to have curtailed vCJD, there is concern that CWD of free-ranging deer and elk in the U.S. might also cross the species barrier. Thus, consuming venison could be a source of human prion disease. Whether BSE and CWD represent interspecies scrapie transfer or are newly arisen prion diseases is unknown. Therefore, the possibility of transmission of prion disease through other food animals cannot be ruled out. There is evidence that vCJD can be transmitted through blood transfusion. There is likely a pool of unknown size of asymptomatic individuals infected with vCJD, and there may be asymptomatic individuals infected with the CWD equivalent. These circumstances represent a potential threat to blood, blood products, and plasma supplies.