Volume 27, Number 12—December 2021
Dispatch
Experimental Oronasal Transmission of Chronic Wasting Disease Agent from White-Tailed Deer to Suffolk Sheep
Eric D. Cassmann, S. Jo Moore, and Justin J. GreenleeComments to Author
Author affiliation: US Department of Agriculture, Ames, Iowa, USA
Abstract
Chronic wasting disease (CWD) is a fatal prion disease of cervids. We examined host range of CWD by oronasally inoculating Suffolk sheep with brain homogenate from a CWD-positive white-tailed deer. Sixty months after inoculation, 1/7 sheep had immunoreactivity against the misfolded form of prion protein in lymphoid tissue. Results were confirmed by mouse bioassay.
Transmissible spongiform encephalopathies (TSEs), also known as prion diseases, are a group of fatal neurologic diseases caused by a misfolded form of the prion protein (PrPSc). Several TSEs affect livestock, including scrapie in sheep and chronic wasting disease (CWD) in cervids.
Susceptibility of sheep to the agent of scrapie is determined by the host prion protein genotype. Three polymorphisms at codons 136, 154, and 171 of the prion protein gene occur in sheep. The haplotype A136R154R171 is associated with resistance to scrapie, whereas VRQ is linked with susceptibility. Likewise, the deer prion protein genotype GG96 is overrepresented in cases of CWD.
CWD was identified in captive mule deer in Colorado, USA, in 1967 (1). Since then, CWD has been reported in >24 states in the United States, 2 provinces in Canada, and South Korea (2,3). During 2016, CWD was reported in Europe, and it has since been detected in 3 Nordic countries (Norway, Sweden, and Finland), although CWD strains in Europe were recently shown to be distinct from strains in North America (4). Because of human consumption of cervid meat products and intermingling of various livestock species with wild cervid populations, there is major interest in characterizing the possible host range of CWD.
Scrapie has been implicated as the possible source of CWD in cervids (5). This finding is supported by in vitro conversion of sheep prion protein by infectious CWD prions (6) and glycoprofile similarities between scrapie and CWD prions (7). Another similarity between scrapie and CWD is prominent lymphoid accumulation of PrPSc in both species affected (5). Experimental transmission of mule deer CWD to Suffolk sheep by intracranial inoculation, a highly artificial route of transmission, has been performed (8). Widespread peripheral lymphoid accumulation of PrPSc is retained in intracranially CWD inoculated sheep.
The objective of this study was to test the oronasal susceptibility of sheep to the agent of CWD. We report the preliminary findings of an ongoing multiyear study.
The Study Initially, we oronasally inoculated (9) seven Suffolk lambs (3‒4 months of age) with the V136R154Q171/ARQ (n = 2), ARQ/ARQ (n = 4), or ARQ/ARR (n = 1) prion protein genotype and 0.1 g of 10% (wt/vol) brain homogenate from a GG96 white-tailed deer that had CWD. The sheep were housed indoors in a Biosafety Level 2 agriculture facility separate from scrapie-affected sheep. At 60 months postinoculation, the initial experimental endpoint, sheep were asymptomatic, and all 7 sheep were culled.
We performed a postmortem examination on each sheep and collected a full spectrum of tissues, which we froze and stored in 10% neutral-buffered formalin. To evaluate lymphoinvasion and neuroinvasion, we tested tissues from the brainstem at the obex and pons, third eyelid, palatine tonsil, lymph nodes (mesenteric and retropharyngeal), spleen, and ileum. We processed the formalin-fixed tissues, embedded in paraffin, and sectioned at optimal thickness (brain, 4 µm; lymphoid, 3 µm; and other tissues, 5 µm) for subsequent staining with hematoxylin and eosin and immunohistochemical (IHC) analysis. We used a cocktail of PrPSc monoclonal antibodies (F89/160.1.5 and F99/97.6.1; 5 μg/mL) for IHC.
Immunoreactivity against misfolded form of the prion protein (red) in lymphoid tissue from a sheep oronasally inoculated with the agent of chronic wasting disease from white-tailed deer. A) Retropharyngeal lymph node (original magnification ×100.) B) Palatine tonsil (original magnification ×40). We used a cocktail of monoclonal antibodies (F89/160.1.5 and F99/97.6.1). Figure 1. Immunoreactivity against misfolded form of the prion protein (red) in lymphoid tissue from a sheep oronasally inoculated with the agent of chronic wasting disease from white-tailed deer. A) Retropharyngeal lymph...
Examination of IHC-stained tissues showed PrPSc in the retropharyngeal lymph node (Figure 1, panel A) and palatine tonsil (Figure 1, panel B) of 1 sheep inoculated with the ARQ/ARQ genotype. The retropharyngeal lymph node was also positive by enzyme immunoassay (EIA) (HerdChek; IDEXX Laboratories, https://www.idexx.comExternal Link) at initial (optical density 0.99; negative cutoff value 0.186) and repeat (optical density 0.559; negative cutoff value 0.178) tests. The palatine tonsil was negative by EIA.
To confirm prion disease infectivity in the retropharyngeal lymph node, we performed bioassays in Tg12 cervidized (10) and Tg338 ovinized (11) transgenic mice. Mice expressed the transgene for the elk prion protein polymorphism MM132 (Tg12) and the ovine prion protein polymorphisms V136R154Q171 (Tg338). We homogenized fresh frozen lymph nodes to 10% (wt/vol) and enriched them by repeated rounds of differential centrifugation; we intracranially inoculated mice with 20 μL of 10% (wt/vol) equivalent enriched homogenate. The Tg12 bioassay had a partial attack rate of 5/9 mice. Most (4/5) dead Tg12 mice were strongly positive by EIA (optical density 4.0) and had an average incubation period of 511 days.
Western blot analysis showing proteinase K‒resistant misfolded form of the prion protein (PrPSc) in brains of 4 Tg12 mice. Mice were intracranially inoculated with a homogenate made from retropharyngeal lymph node of a sheep oronasally inoculated with the agent of chronic wasting disease. Tg12 brain was prepared as a 10% (wt/vol) homogenate with phosphate-buffered saline. A total of 1 mg of tissue equivalent was treated with proteinase K (90 μg/mL) before electrophoresis. Immunodetection of PrPSc was performed overnight at 4°C with monoclonal antibody Sha31 (dilution 1:10,000). Left lane, molecular mass ladder. kDa, kilodaltons. Figure 2. Western blot analysis showing proteinase K‒resistant misfolded form of the prion protein (PrPSc) in brains of 4 Tg12 mice. Mice were intracranially inoculated with a homogenate made from...
Western blots of these 4 Tg12 mice confirmed the presence of proteinase K‒resistant PrPSc in the brains (Figure 2). The positive EIA results were obtained from brain homogenates in Tg12 mice; the spleens were negative for PrPSc. For the Tg338 bioassay (n = 15), brains and spleens were negative by EIA. Four Tg338 mice that died or were euthanized because of intercurrent disease at 254, 462, 629, and 657 days postinoculation were negative by EIA. The rest of the Tg338 mice were negative at the study endpoint, 700 days postinoculation.
Top
Conclusions The oronasal susceptibility of sheep to the agent of CWD is a major finding in light of its possible effect on risk assessment and understanding possible transmission of CWD to noncervid species in field conditions. Interspecies transmission of TSEs is less likely when the experimental species barrier between hosts is strong (12). One study demonstrated that the CWD agent does not readily transmit to transgenic ovinized mice (13). However, another study reported lifelong replication of PrPSc in the spleen after intracranial inoculation of the CWD agent in Tg338 ovinized mice (14). The finding of extraneuronal PrPSc in 1 sheep 5 years after oral inoculation suggests that sheep are unlikely to develop neurologic disease after natural exposure to the agent of CWD, but they might serve as asymptomatic carriers under the right conditions.
In this study, we used a relatively low dose (0.1 g) of brain homogenate. These results are intriguing, but they do not assess potential modes of transmission that could occur in the field, such as nose-to-nose contact or environmental contamination. In our ongoing multiyear study, 1 sheep had PrPSc-positive lymphoid tissue but no evidence of neuroinvasion 5 years postinoculation. This time interval is an extremely protracted incubation period. Had we continued this experiment, it is unknown how long the sheep would have remained asymptomatic or whether they would have eventually developed clinical disease. Because PrPSc was detected in lymphoid tissues of the head, the possibility that this sheep might have been shedding infectivity into the environment cannot be ruled out.
Positive bioassay results in Tg12 mice confirm CWD infectivity in the lymph node. Negative results in Tg338 mice could be explained by a donor/host mismatch between the ARQ donor sheep and VRQ expressing mice. Pursuing bioassays in A136-expressing transgenic mice could be more fruitful.
Interspecies transmission events might increase the pathogenicity of an infectious prion on subsequent transmission to other species (15). Thus, exploration of potential new host ranges of this CWD isolate and performing human health risk assessments will provide useful information for this prion.
Dr. Cassmann is a research veterinary medical officer at the National Animal Disease Center, Ames, IA. His primary research interests are veterinary pathology, animal prion diseases, interspecies transmission, host ranges, host genetic susceptibility, and diagnostics.
Acknowledgments
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Research Project: Pathobiology, Genetics, and Detection of Transmissible Spongiform Encephalopathies Location: Virus and Prion Research
Title: Experimental oronasal transmission of the CWD agent from whitetail deer to Suffolk sheep
Author item Cassmann, Eric item MOORE, SARA JO - Orise Fellow item Greenlee, Justin Submitted to: Emerging Infectious Diseases Publication Type: Peer Reviewed Journal Publication Acceptance Date: 8/20/2021 Publication Date: N/A Citation: N/A Interpretive
Summary: Transmissible spongiform encephalopathies (TSEs) are a group of fatal diseases caused by the accumulation of misfolded prion protein in the brain. Several livestock species including sheep, deer, and elk are afflicted by prion diseases. In sheep the disease is called scrapie. In deer and elk, the disease is called chronic wasting disease (CWD). The source of CWD is unknown, but it is speculated that the origin of CWD may have been due to a species jump of scrapie in sheep to deer. Due to the human consumption of cervid meat products and intermingling of various livestock species with wild cervid populations, there is significant interest in characterizing the possible host range of CWD. This study reports preliminary results of an ongoing multi-year experiment on the oronasal transmission of CWD from white-tailed deer to sheep. After a five-year period, 1/7 sheep had detectable CWD prions in the retropharyngeal lymph nodes and tonsil. Infectivity of these prions was confirmed using a bioassay with transgenic mice expressing cervid prion protein. These results demonstrate the susceptibility of sheep to the agent of CWD after a prolonged incubation period. Since the original experiment ended after five years, it is unknown if the sheep would have remained asymptomatic or developed clinical prion disease given a longer incubation period. It is also unknown if sheep are capable of shedding or transmitting CWD prions. Additional work is necessary to further characterize the transmission properties of the CWD agent in sheep and other species.
Technical Abstract: CWD is a fatal prion disease of cervids. This study examined the host range of CWD by orally inoculating Suffolk sheep with brain homogenate from a CWD positive white-tailed deer. Sixty-months after oronasal inoculation, 1/7 sheep had immunoreactivity against PrPSc in the lymphoid tissue that was confirmed by mouse bioassay.
Research Project: TRANSMISSION, DIFFERENTIATION, AND PATHOBIOLOGY OF TRANSMISSIBLE SPONGIFORM ENCEPHALOPATHIES Location: Virus and Prion Research
Title: Scrapie transmits to white-tailed deer by the oral route and has a molecular profile similar to chronic wasting disease
Author
item Greenlee, Justin item Moore, S - Orise Fellow item Smith, Jodi - Iowa State University item Kunkle, Robert item West Greenlee, M - Iowa State University Submitted to: American College of Veterinary Pathologists Meeting Publication Type: Abstract Only Publication Acceptance Date: 8/12/2015 Publication Date: N/A Citation: N/A
Interpretive Summary:
Technical Abstract: The purpose of this work was to determine susceptibility of white-tailed deer (WTD) to the agent of sheep scrapie and to compare the resultant PrPSc to that of the original inoculum and chronic wasting disease (CWD). We inoculated WTD by a natural route of exposure (concurrent oral and intranasal (IN); n=5) with a US scrapie isolate. All scrapie-inoculated deer had evidence of PrPSc accumulation. PrPSc was detected in lymphoid tissues at preclinical time points, and deer necropsied after 28 months post-inoculation had clinical signs, spongiform encephalopathy, and widespread distribution of PrPSc in neural and lymphoid tissues. Western blotting (WB) revealed PrPSc with 2 distinct molecular profiles. WB on cerebral cortex had a profile similar to the original scrapie inoculum, whereas WB of brainstem, cerebellum, or lymph nodes revealed PrPSc with a higher profile resembling CWD. Homogenates with the 2 distinct profiles from WTD with clinical scrapie were further passaged to mice expressing cervid prion protein and intranasally to sheep and WTD. In cervidized mice, the two inocula have distinct incubation times. Sheep inoculated intranasally with WTD derived scrapie developed disease, but only after inoculation with the inoculum that had a scrapie-like profile. The WTD study is ongoing, but deer in both inoculation groups are positive for PrPSc by rectal mucosal biopsy. In summary, this work demonstrates that WTD are susceptible to the agent of scrapie, two distinct molecular profiles of PrPSc are present in the tissues of affected deer, and inoculum of either profile readily passes to deer.
***> “In summary, this work demonstrates that WTD are susceptible to the agent of scrapie, two distinct molecular profiles of PrPSc are present in the tissues of affected deer, and inoculum of either profile readily passes to deer.”
223. Scrapie in white-tailed deer: a strain of the CWD agent that efficiently transmits to sheep?
Justin J. Greenleea, Robyn D. Kokemullera, S. Jo Moorea and Heather West Greenleeb
aVirus and Prion Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, Ames, IA, USA; bDepartment of Biomedical Sciences, Iowa State University College of Veterinary Medicine, Ames, IA, USA
CONTACT Justin J. Greenlee Justin.Greenlee@ars.usda.gov
ABSTRACT
Scrapie is a transmissible spongiform encephalopathy of sheep and goats that is associated with widespread accumulation of abnormal prion protein (PrPSc) in the central nervous and lymphoid tissues. Chronic wasting disease (CWD) is the natural prion disease of cervid species, and the tissue distribution of PrPSc in affected cervids is similar to scrapie in sheep. There are several lines of evidence that suggest that multiple strains of CWD exist, which may affect the agent’s potential to transmit to hosts of the same or different species. We inoculated white-tailed deer with the scrapie agent from ARQ/ARQ sheep, which resulted in 100% attack rates by either the intracranial or oronasal route of inoculation. When examining tissues from the brainstems or lymphoid tissues by traditional diagnostic methods such as immunohistochemistry or western blots, it is difficult to differentiate tissues from deer infected with scrapie from those infected with CWD. However, there are several important differences between tissues from scrapie-infected white-tailed deer (WTD scrapie) and those infected with CWD (WTD CWD). First, there are different patterns of PrPSc deposition in the brains of infected deer: brain tissues from deer with WTD scrapie had predominantly particulate and stellate immunoreactivity whereas those from deer with WTD-CWD had large aggregates and plaque-like deposits. Secondly, the incubation periods of WTD scrapie isolates are longer than CWD isolates in mice expressing cervid prion protein. Most notably, the transmission potential of these two isolates back to sheep is distinctly different. Attempts to transmit various CWD isolates to sheep by the oral or oronasal routes have been unsuccessful despite observation periods of up to 7 years. However, WTD scrapie efficiently transmitted back to sheep by the oronasal route. Upon transmission back to sheep, the WTD scrapie isolate exhibited different phenotypic properties when compared to the sheep receiving the original sheep scrapie inoculum including different genotype susceptibilities, distinct PrPSc deposition patterns, and much more rapid incubation periods in transgenic mice expressing the ovine prion protein. The scrapie agent readily transmits between sheep and deer after oronasal exposure. This could confound the identification of CWD strains in deer and the eradication of scrapie from sheep.
***> “The scrapie agent readily transmits between sheep and deer after oronasal exposure. This could confound the identification of CWD strains in deer and the eradication of scrapie from sheep.”
Title: Scrapie transmits to white-tailed deer by the oral route and has a molecular profile similar to chronic wasting disease
J Vet Diagn Invest . 2021 Jul;33(4):711-720. doi: 10.1177/10406387211017615. Epub 2021 May 28. D Cassmann 1, Rylie D Frese 1, Justin J Greenlee 1
Affiliations expand PMID: 34047228 PMCID: PMC8229824 (available on 2022-05-28)DOI: 10.1177/10406387211017615 Full text linksCite Abstract
The origin of chronic wasting disease (CWD) in cervids is unclear. One hypothesis suggests that CWD originated from scrapie in sheep. We compared the disease phenotype of sheep-adapted CWD to classical scrapie in sheep. We inoculated sheep intracranially with brain homogenate from first-passage mule deer CWD in sheep (sCWDmd). The attack rate in second-passage sheep was 100% (12 of 12). Sheep had prominent lymphoid accumulations of PrPSc reminiscent of classical scrapie. The pattern and distribution of PrPSc in the brains of sheep with CWDmd was similar to scrapie strain 13-7 but different from scrapie strain x124. The western blot glycoprofiles of sCWDmd were indistinguishable from scrapie strain 13-7; however, independent of sheep genotype, glycoprofiles of sCWDmd were different than x124. When sheep genotypes were evaluated individually, there was considerable overlap in the glycoprofiles that precluded significant discrimination between sheep CWD and scrapie strains. Our data suggest that the phenotype of CWD in sheep is indistinguishable from some strains of scrapie in sheep. Given our results, current detection techniques would be unlikely to distinguish CWD in sheep from scrapie in sheep if cross-species transmission occurred naturally. It is unknown if sheep are naturally vulnerable to CWD; however, the susceptibility of sheep after intracranial inoculation and lymphoid accumulation indicates that the species barrier is not absolute.
Keywords: PrPSc proteins; chronic wasting disease; deer; prions; scrapie; sheep.
***> ”Our data suggest that the phenotype of CWD in sheep is indistinguishable from some strains of scrapie in sheep. Given our results, current detection techniques would be unlikely to distinguish CWD in sheep from scrapie in sheep if cross-species transmission occurred naturally.”
Title: Second passage of chronic wasting disease of mule deer in sheep compared to classical scrapie after intracranial inoculation
Taken together, these data suggest that the phenotype of CWD in sheep is indistinguishable from some strains of scrapie in sheep.
''We inoculated WTD by a natural route of exposure (concurrent oral and intranasal (IN); n=5) with a US scrapie isolate. All scrapie-inoculated deer had evidence of PrPSc accumulation.''
Title: Passage of scrapie to deer results in a new phenotype upon return passage to sheep
Title: Transmission of the agent of sheep scrapie to deer results in PrPSc with two distinct molecular profiles
***> In summary, this work demonstrates that WTD are susceptible to the agent of scrapie, two distinct molecular profiles of PrPSc are present in the tissues of affected deer, and inoculum of either profile type readily passes to deer.
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.
Conclusions: This study demonstrates that PrPSc accumulates in lymphoid tissues from pigs challenged intracranially or orally with the CWD agent, and can be detected as early as 4 months after challenge. CWD-infected pigs rarely develop clinical disease and if they do, they do so after a long incubation period. This raises the possibility that CWD-infected pigs could shed prions into their environment long before they develop clinical disease. Furthermore, lymphoid tissues from CWD-infected pigs could present a potential source of CWD infectivity in the animal and human food chains.
CONFIDENTIAL
EXPERIMENTAL PORCINE SPONGIFORM ENCEPHALOPATHY
LINE TO TAKE
3. If questions on pharmaceuticals are raised at the Press conference, the suggested line to take is as follows:-
"There are no medicinal products licensed for use on the market which make use of UK-derived porcine tissues with which any hypothetical “high risk" ‘might be associated. The results of the recent experimental work at the CSM will be carefully examined by the CSM‘s Working Group on spongiform encephalopathy at its next meeting.
DO Hagger RM 1533 MT Ext 3201
While this clearly is a cause for concern we should not jump to the conclusion that this means that pigs will necessarily be infected by bone and meat meal fed by the oral route as is the case with cattle. ...
we cannot rule out the possibility that unrecognised subclinical spongiform encephalopathy could be present in British pigs though there is no evidence for this: only with parenteral/implantable pharmaceuticals/devices is the theoretical risk to humans of sufficient concern to consider any action.
May I, at the outset, reiterate that we should avoid dissemination of papers relating to this experimental finding to prevent premature release of the information. ...
3. It is particularly important that this information is not passed outside the Department, until Ministers have decided how they wish it to be handled. ...
But it would be easier for us if pharmaceuticals/devices are not directly mentioned at all. ...
Our records show that while some use is made of porcine materials in medicinal products, the only products which would appear to be in a hypothetically ''higher risk'' area are the adrenocorticotrophic hormone for which the source material comes from outside the United Kingdom, namely America China Sweden France and Germany. The products are manufactured by Ferring and Armour. A further product, ''Zenoderm Corium implant'' manufactured by Ethicon, makes use of porcine skin - which is not considered to be a ''high risk'' tissue, but one of its uses is described in the data sheet as ''in dural replacement''. This product is sourced from the United Kingdom.....
***> 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.
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
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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.
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2.3.2. New evidence on the zoonotic potential of atypical BSE and atypical scrapie prion strains
PLEASE NOTE;
2.3.2. New evidence on the zoonotic potential of atypical BSE and atypical scrapie prion strainsNo
Olivier Andreoletti, INRA Research Director, Institut National de la Recherche Agronomique (INRA) – École Nationale Vétérinaire de Toulouse (ENVT), invited speaker, presented the results of two recently published scientific articles of interest, of which he is co-author: ‘Radical Change in Zoonotic Abilities of Atypical BSE Prion Strains as Evidenced by Crossing of Sheep Species Barrier in Transgenic Mice’ (MarinMoreno et al., 2020) and ‘The emergence of classical BSE from atypical/Nor98 scrapie’ (Huor et al., 2019).
In the first experimental study, H-type and L-type BSE were inoculated into transgenic mice expressing all three genotypes of the human PRNP at codon 129 and into adapted into ARQ and VRQ transgenic sheep mice. The results showed the alterations of the capacities to cross the human barrier species (mouse model) and emergence of sporadic CJD agents in Hu PrP expressing mice: type 2 sCJD in homozygous TgVal129 VRQ-passaged L-BSE, and type 1 sCJD in homozygous TgVal 129 and TgMet129 VRQ-passaged H-BSE.
FRIDAY, NOVEMBER 19, 2021
EFSA Annual Report of the Scientific Network on BSE-TSE 2021
TUESDAY, SEPTEMBER 07, 2021
Atypical Bovine Spongiform Encephalopathy BSE OIE, FDA 589.2001 FEED REGULATIONS, and Ingestion Therefrom
Terry S. Singeltary Sr.
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