CWD Minnesota deer feeding ban covering Dodge, Goodhue, Olmsted, and Wabasha counties will become effective Feb. 14, 2011
Managing Chronic Wasting Disease
Minnesota DNR officials are asking landowners in a portion of southeastern Minnesota within roughly 10 miles of where a Chronic Wasting Disease (CWD) positive wild deer was found to assist with the agency's disease sampling efforts.
Landowners who accept shooting permits will be allowed to take deer themselves or authorize additional shooters to take deer. There will be no tradtional special hunt because all the land in the surveillance area is private land that cannot be hunted without permission.
Population estimates indicate there are 6,500 deer in the CWD survelliance area, which stretches from Wanamingo, Zumbrota and Zumbro Falls southward to Kasson, Byron and Rochester. DNR, working with landowners, will harvest 900 deer within the survelliance area, 500 of which will be taken within a roughly five-mile radius of the confirmed CWD-positive deer. Each will be tested for CWD.
A deer feeding ban covering Dodge, Goodhue, Olmsted, and Wabasha counties will become effective Feb. 14. The feeding ban includes a wider area because the potential extent of the CWD infection is not known and one of the most probable mechanisms for CWD spread among deer is over a food source that concentrates animals.
People interested in learning more about efforts to manage CWD in the area should attend a DNR public input meeting from 7-9 p.m. on Monday, Feb. 14, at the Pine Island High School Cafeteria.
Friday, January 21, 2011
MINNESOTA HIGHLY SUSPECT CWD POSITIVE WILD DEER FOUND NEAR PINE ISLAND
UPDATED DATA ON 2ND CWD STRAIN
Wednesday, September 08, 2010
CWD PRION CONGRESS SEPTEMBER 8-11 2010
Our findings demonstrate that cervid PrPSc, upon strain adaptation by serial passages in vitro or in cervid transgenic mice, is capable of converting human PrPC to produce PrPSc with unique biochemical properties, likely representing a new human prion strain. The newly generated CWD-huPrPSc material has been inoculated into transgenic mice expressing human PrP to study infectivity and disease phenotype and this data will be published elsewhere.
Generation of a new form of human PrPSc in vitro by inter-species transmission from cervids prions
Marcelo A. Barria1, Glenn C. Telling2, Pierluigi Gambetti3, James A. Mastrianni4 and Claudio Soto1,*
1Mitchell Center for Alzheimer’s disease and related Brain disorders, Dept of Neurology, University of Texas Houston Medical School, Houston, TX 77030, USA
2Dept of Microbiology, Immunology & Molecular Genetics, and Neurology, Sanders Brown Center on Aging, University of Kentucky Medical Center, Lexington, KY, USA
3Institute of Pathology, Case Western Reserve University, Cleveland, OH, USA
4Dept of Neurology, University of Chicago, Chicago, IL, USA.
Running Title: Conversion of human PrPC by cervid PrPSc
Keywords: Prion / transmissible spongiform encephalopathy / infectivity / misfolded prion protein / prion strains
* To whom correspondence should be addressed. University of Texas Houston Medical School, 6431 Fannin St, Houston, TX 77030. Tel 713-5007086; Fax 713-5000667; E-mail Claudio.Soto@uth.tmc.edu
Prion diseases are infectious neurodegenerative disorders affecting humans and animals that result from the conversion of normal prion protein (PrPC) into the misfolded prion protein (PrPSc). Chronic wasting disease (CWD) is a prion disorder of increasing prevalence within the United States that affects a large population of wild and captive deer and elk. Determining the risk of transmission of CWD to humans is of utmost importance, considering that people can be infected by animal prions, resulting in new fatal diseases. To study the possibility that human PrPC can be converted into the misfolded form by CWD PrPSc we performed experiments using the Protein Misfolding Cyclic Amplification (PMCA) technique, which mimic in vitro the process of prion replication. Our results show that cervid PrPSc can induce the conversion of human PrPC, but only after the CWD prion strain has been stabilized by successive passages in vitro or in vivo. Interestingly, the newly generated human PrPSc exhibits a distinct biochemical pattern that differs from any of the currently known forms of human PrPSc. Our results also have profound implications for understanding the mechanisms of prion species barrier and indicate that the transmission barrier is a dynamic process that depend on the strain and moreover the degree of adaptation of the strain. If our findings are corroborated by infectivity assays, they will imply that CWD prions have the potential to infect humans, and that this ability depends on CWD strain adaptation.
Interestingly, when the Western blot profile of this newly generated form of human PrPSc (termed CWD-huPrPSc) was compared with known strains of human prions, it was clear that CWD-huPrPSc exhibited a different pattern (Fig. 4A). The electrophoretic migration of this protein after PK-digestion is similar to the type 1 strain of sCJD, but its glycosylation profile is clearly different, showing a highly predominant diglycosylated form (Fig. 4A and B). This result suggests that CWD hu-PrPSc corresponds to a new human prion strain. Interestingly, a detailed previous study from Gambetti’s group comparing the biochemical characteristics of PrPSc from cervids and humans showed that CWD PrPSc is similar to sCJDMM1 in terms of electrophoretic mobility (6). However, the misfolded protein associated with CWD is predominantly di-glycosylated, whereas PrPSc from type 1 sCJD is mostly monoglycosylated (6). Based on the fact that transmission of BSE prions to humans resulted in a new form of PrPSc very similar to the one in cattle (6;27), these authors predicted that if humans were infected by CWD it is likely that PrPSc would be of type 1 and with a predominance of the diglycosylated isoform (6). Our results agree with that prediction and suggest that the newly generated CWD-huPrPSc acquires the biochemical properties of the cervid infectious material (Fig. 4A and B). We and others have shown that PMCA replication of PrPSc obtained from experimental rodents, sheep, cervid and human samples faithfully maintains the prion strain characteristics (14;16;26;28-30). To further support the relevance of our results, we performed experiments in which human PrPC was attempted to be converted by either cattle BSE PrPSc or sheep scrapie PrPSc. Whereas the typical vCJD type of PrPSc was generated when human PrPC was converted by BSE PrPSc (Fig. 4C), no human PrPSc was generated under any condition when sheep scrapie PrPSc was used as inoculum (Fig. 4C). These results further validate our PMCA assay.
Discussion CWD is possibly the most worrisome prion zoonosis, because it affects free-ranging animals, making it very difficult to control its spread, and because it is highly efficiently transmitted (1;2). Indeed, in dense free-ranging cervid populations, CWD prevalence can reach as high as 30%, and among captive herds, the prevalence can climb to nearly 100%. The mechanisms and routes of transmission are currently unknown, but likely involve horizontal spread through exposure to prion infected secretions, excretions, or decomposed carcasses (1;2). Moreover, it is likely that CWD prions are progressively accumulating in the environment, since PrPSc binds tightly to soil and can maintain infectivity for a long time (31-33). Currently, it is unknown what proportion of natural CWD cases arises sporadically or comes from horizontal transmission among animals. Based on the available knowledge of the emergence, adaptation and stabilization of prion strains, it is likely that prions appear either spontaneously, through inter-species transmission or by genetic mutations. These “first generation” prions are unstable strains that begin a progressive and gradual process of adaptation that may take several passages and years or decades to complete. In addition natural strain stabilization may take considerable more time than the controlled adaptation done by intracerebral inoculation of brain homogenates in experimental animals. In natural cases, animals usually get infected by peripheral (most likely oral) exposure to small quantities of prions present in peripheral tissues or secretion fluids. Recent data indicates that in some cases the strain characteristics of natural prions in peripheral organs are different than those in the brain even in the same individuals (GCT, unpublished results; MAB and CS, unpublished data). In cervids, there are at least two different strains that can be differentiated by the incubation time and neuropathological characteristics produced when inoculated into transgenic mice expressing deer PrP (34). It is currently unknown the susceptibility of these two strains to human transmission.
Our findings demonstrate that cervid PrPSc, upon strain adaptation by serial passages in vitro or in cervid transgenic mice, is capable of converting human PrPC to produce PrPSc with unique biochemical properties, likely representing a new human prion strain. The newly generated CWD-huPrPSc material has been inoculated into transgenic mice expressing human PrP to study infectivity and disease phenotype and this data will be published elsewhere. We have safely ruled out that human PrPSc generated in these studies is not coming from spontaneous “de novo generation”, since under the conditions used, no spontaneous PK-resistant band was ever detected in brain homogenates of humans or transgenic mice expressing human PrPC, even after more than 20 serial rounds of PMCA (35). Furthermore, none of the many controls included in our experiments in which no PrPSc was added to the reaction, showed any PK-resistant PrP band.
Various studies aimed to analyze the transmission of CWD to transgenic mice expressing human PrP have consistently given negative results (9-11), indicating a strong species barrier. This conclusion is consistent with our many failed experiments to attempt converting human PrPC with natural CWD, even after pushing the PMCA conditions (see figure 1). We found successful conversion only after adaptation of the CWD prion strain by successive passages in vitro or in cervid transgenic mice. We are not aware that in any of the transgenic mice studies the inoculum used was a previously stabilized CWD strain. Although, it has been shown that strain stabilization in vitro by PMCA (17;26) and in vivo using experimental rodents (36) has similarities with the strain adaptation process occurring in natural hosts, we cannot rule out that the type of CWD strain adaptation that is required to produce strains transmissible to humans may take much longer time in cervids or not occur at all. An important experiment will be to study transmissibility to humanized transgenic mice of CWD passed experimentally in deer several times.
Besides the importance of our results for public health in relation to the putative transmissibility of CWD to humans, our data also illustrate a very important and novel scientific concept related to the mechanism of prion transmission across species barriers. Today the view is that species barrier is mostly controlled by the degree of similarity on the sequence of the prion protein between the host and the infectious material (4). In our study we show that the strain and moreover the stabilization of the strain plays a major role in the inter-species transmission. In our system there is no change on the protein sequence, but yet strain adaptation results in a complete change on prion transmissibility with potentially dramatic consequences. Therefore, our findings lead to a new view of the species barrier that should not be seen as a static process, but rather a dynamic biological phenomenon that can change over time when prion strains mature and evolve. It remains to be investigated if other species barriers also change upon progressive strain adaptation of other prion forms (e.g. the sheep/human barrier).
Our results have far-reaching implications for human health, since they indicate that cervid PrPSc can trigger the conversion of human PrPC into PrPSc, suggesting that CWD might be infectious to humans. Interestingly our findings suggest that unstable strains from CWD affected animals might not be a problem for humans, but upon strain stabilization by successive passages in the wild, this disease might become progressively more transmissible to man.
please see full text and many thanks to the Professor Soto and the other Authors of this study AND to The Journal Of Biological Chemistry for the free full text !!!
PLEASE NOTE ;
there are now two documented strains of CWD, and science is showing that indeed CWD could transmit to humans via transmission studies ;
ADAPTATION OF CHRONIC WASTING DISEASE (CWD) INTO HAMSTERS, EVIDENCE OF A WISCONSIN STRAIN OF CWD
Chad Johnson1, Judd Aiken2,3,4 and Debbie McKenzie4,5 1 Department of Comparative Biosciences, University of Wisconsin, Madison WI, USA 53706 2 Department of Agriculture, Food and Nutritional Sciences, 3 Alberta Veterinary Research Institute, 4.Center for Prions and Protein Folding Diseases, 5 Department of Biological Sciences, University of Alberta, Edmonton AB, Canada T6G 2P5
The identification and characterization of prion strains is increasingly important for the diagnosis and biological definition of these infectious pathogens. Although well-established in scrapie and, more recently, in BSE, comparatively little is known about the possibility of prion strains in chronic wasting disease (CWD), a disease affecting free ranging and captive cervids, primarily in North America. We have identified prion protein variants in the white-tailed deer population and demonstrated that Prnp genotype affects the susceptibility/disease progression of white-tailed deer to CWD agent. The existence of cervid prion protein variants raises the likelihood of distinct CWD strains. Small rodent models are a useful means of identifying prion strains. We intracerebrally inoculated hamsters with brain homogenates and phosphotungstate concentrated preparations from CWD positive hunter-harvested (Wisconsin CWD endemic area) and experimentally infected deer of known Prnp genotypes. These transmission studies resulted in clinical presentation in primary passage of concentrated CWD prions. Subclinical infection was established with the other primary passages based on the detection of PrPCWD in the brains of hamsters and the successful disease transmission upon second passage. Second and third passage data, when compared to transmission studies using different CWD inocula (Raymond et al., 2007) indicate that the CWD agent present in the Wisconsin white-tailed deer population is different than the strain(s) present in elk, mule-deer and white-tailed deer from the western United States endemic region.
Prion Transmission from Cervids to Humans is Strain-dependent
Qingzhong Kong, Shenghai Huang,*Fusong Chen, Michael Payne, Pierluigi Gambetti and Liuting Qing Department of Pathology; Case western Reserve University; Cleveland, OH USA *Current address: Nursing Informatics; Memorial Sloan-Kettering Cancer Center; New York, NY USA
Key words: CWD, strain, human transmission
Chronic wasting disease (CWD) is a widespread prion disease in cervids (deer and elk) in North America where significant human exposure to CWD is likely and zoonotic transmission of CWD is a concern. Current evidence indicates a strong barrier for transmission of the classical CWD strain to humans with the PrP-129MM genotype. A few recent reports suggest the presence of two or more CWD strains. What remain unknown is whether individuals with the PrP-129VV/MV genotypes are also resistant to the classical CWD strain and whether humans are resistant to all natural or adapted cervid prion strains. Here we report that a human prion strain that had adopted the cervid prion protein (PrP) sequence through passage in cervidized transgenic mice efficiently infected transgenic mice expressing human PrP, indicating that the species barrier from cervid to humans is prion strain-dependent and humans can be vulnerable to novel cervid prion strains. Preliminary results on CWD transmission in transgenic mice expressing human PrP-129V will also be discussed.
Acknowledgement Supported by NINDS NS052319 and NIA AG14359.
Generation of a Novel form of Human PrPSc by Inter-species Transmission of Cervid Prions
Marcelo A. Barria,1 Glenn C. Telling,2 Pierluigi Gambetti,3 James A. Mastrianni4 and Claudio Soto1 1Mitchell Center for Alzheimer's disease and related Brain disorders; Dept of Neurology; University of Texas Houston Medical School; Houston, TX USA; 2Dept of Microbiology, Immunology & Molecular Genetics and Neurology; Sanders Brown Center on Aging; University of Kentucky Medical Center; Lexington, KY USA; 3Institute of Pathology; Case western Reserve University; Cleveland, OH USA; 4Dept of Neurology; University of Chicago; Chicago, IL USA
Prion diseases are infectious neurodegenerative disorders affecting humans and animals that result from the conversion of normal prion protein (PrPC) into the misfolded and infectious prion (PrPSc). Chronic wasting disease (CWD) of cervids is a prion disorder of increasing prevalence within the United States that affects a large population of wild and captive deer and elk. CWD is highly contagious and its origin, mechanism of transmission and exact prevalence are currently unclear. The risk of transmission of CWD to humans is unknown. Defining that risk is of utmost importance, considering that people have been infected by animal prions, resulting in new fatal diseases. To study the possibility that human PrPC can be converted into the infectious form by CWD PrPSc we performed experiments using the Protein Misfolding Cyclic Amplification (PMCA) technique, which mimic in vitro the process of prion replication. Our results show that cervid PrPSc can induce the pathological conversion of human PrPC, but only after the CWD prion strain has been stabilized by successive passages in vitro or in vivo. Interestingly, this newly generated human PrPSc exhibits a distinct biochemical pattern that differs from any of the currently known forms of human PrPSc, indicating that it corresponds to a novel human prion strain. Our findings suggest that CWD prions have the capability to infect humans, and that this ability depends on CWD strain adaptation, implying that the risk for human health progressively increases with the spread of CWD among cervids.
Biochemical and Biophysical Characterization of Different CWD Isolates
Martin L. Daus and Michael Beekes Robert Koch Institute; Berlin, Germany
Key words: CWD, strains, FT-IR, AFM
Chronic wasting disease (CWD) is one of three naturally occurring forms of prion disease. The other two are Creutzfeldt-Jakob disease in humans and scrapie in sheep. CWD is contagious and affects captive as well as free ranging cervids. As long as there is no definite answer of whether CWD can breach the species barrier to humans precautionary measures especially for the protection of consumers need to be considered. In principle, different strains of CWD may be associated with different risks of transmission to humans. Sophisticated strain differentiation as accomplished for other prion diseases has not yet been established for CWD. However, several different findings indicate that there exists more than one strain of CWD agent in cervids. We have analysed a set of CWD isolates from white-tailed deer and could detect at least two biochemically different forms of disease-associated prion protein PrPTSE. Limited proteolysis with different concentrations of proteinase K and/or after exposure of PrPTSE to different pH-values or concentrations of Guanidinium hydrochloride resulted in distinct isolate-specific digestion patterns. Our CWD isolates were also examined in protein misfolding cyclic amplification studies. This showed different conversion activities for those isolates that had displayed significantly different sensitivities to limited proteolysis by PK in the biochemical experiments described above. We further applied Fourier transform infrared spectroscopy in combination with atomic force microscopy. This confirmed structural differences in the PrPTSE of at least two disinct CWD isolates. The data presented here substantiate and expand previous reports on the existence of different CWD strains.
Mr R.N. Elmhirst Chairman British Deer Farmers Association Holly Lodge Spencers Lane BerksWell Coventry CV7 7BZ
Dear Mr Elmhirst,
CREUTZFELDT-JAKOB DISEASE (CJD) SURVEILLANCE UNIT REPORT
Thank you for your recent letter concerning the publication of the third annual report from the CJD Surveillance Unit. I am sorry that you are dissatisfied with the way in which this report was published.
The Surveillance Unit is a completely independant outside body and the Department of Health is committed to publishing their reports as soon as they become available. In the circumstances it is not the practice to circulate the report for comment since the findings of the report would not be amended. In future we can ensure that the British Deer Farmers Association receives a copy of the report in advance of publication.
The Chief Medical Officer has undertaken to keep the public fully informed of the results of any research in respect of CJD. This report was entirely the work of the unit and was produced completely independantly of the the Department.
The statistical results reqarding the consumption of venison was put into perspective in the body of the report and was not mentioned at all in the press release. Media attention regarding this report was low key but gave a realistic presentation of the statistical findings of the Unit. This approach to publication was successful in that consumption of venison was highlighted only once by the media ie. in the News at one television proqramme.
I believe that a further statement about the report, or indeed statistical links between CJD and consumption of venison, would increase, and quite possibly give damaging credence, to the whole issue. From the low key media reports of which I am aware it seems unlikely that venison consumption will suffer adversely, if at all.
Experimental oral transmission of chronic wasting disease to red deer (Cervus elaphus elaphus): Early detection and late stage distribution of protease-resistant prion protein
Aru Balachandran, Noel P. Harrington, James Algire, Andrei Soutyrine, Terry R. Spraker, Martin Jeffrey, Lorenzo González, Katherine I. O’Rourke
Abstract — Chronic wasting disease (CWD), an important emerging prion disease of cervids, is readily transmitted by intracerebral or oral inoculation from deer-to-deer and elk-to-elk, suggesting the latter is a natural route of exposure. Studies of host range susceptibility to oral infection, particularly of those species found in habitats where CWD currently exists are imperative. This report describes the experimental transmission of CWD to red deer following oral inoculation with infectious CWD material of elk origin. At 18 to 20 months post-inoculation, mild to moderate neurological signs and weight loss were observed and animals were euthanized and tested using 3 conventional immunological assays. The data indicate that red deer are susceptible to oral challenge and that tissues currently used for CWD diagnosis show strong abnormal prion (PrPCWD) accumulation. Widespread peripheral PrPCWD deposition involves lymphoreticular tissues, endocrine tissues, and cardiac muscle and suggests a potential source of prion infectivity, a means of horizontal transmission and carrier state.
Can Vet J 2010;51:169–178
Chronic wasting disease (CWD), an important emerging prion disease of cervids, is readily transmitted by intracerebral or oral inoculation from deer-to-deer and elk-to-elk, suggesting the latter is a natural route of exposure.
Potential Venison Exposure Among FoodNet Population Survey Respondents, 2006-2007
Ryan A. Maddox1*, Joseph Y. Abrams1, Robert C. Holman1, Lawrence B. Schonberger1, Ermias D. Belay1 Division of Viral and Rickettsial Diseases, National Center for Zoonotic, Vector-Borne, and Enteric Diseases, Centers for Disease Control and Prevention, Atlanta, GA *Corresponding author e-mail: firstname.lastname@example.org
The foodborne transmission of bovine spongiform encephalopathy to humans, resulting in variant Creutzfeldt-Jakob disease, indicates that humans can be susceptible to animal prion diseases. However, it is not known whether foodborne exposure to the agent causing chronic wasting disease (CWD) in cervids can cause human disease. The United States Foodborne Diseases Active Surveillance Network (FoodNet) conducts surveillance for foodborne diseases through an extensive survey administered to respondents in selected states. To describe the frequency of deer and elk hunting and venison consumption, five questions were included in the 2006-2007 FoodNet survey. This survey included 17,372 respondents in ten states: California, Colorado, Connecticut, Georgia, Maryland, Minnesota, New Mexico, New York, Oregon, and Tennessee. Of these respondents, 3,220 (18.5%) reported ever hunting deer or elk, with 217 (1.3%) reporting hunting in a CWD-endemic area (northeastern Colorado, southeastern Wyoming, and southwestern Nebraska). Of the 217 CWD-endemic area hunters, 74 (34.1%) were residents of Colorado. Respondents reporting hunting were significantly more likely to be male than female (prevalence ratio: 3.3, 95% confidence interval: 3.1-3.6) and, in general, older respondents were significantly more likely to report hunting than younger respondents. Venison consumption was reported by more than half (67.4%) of the study population, and most venison consumers (94.1%) reported that at least half of their venison came from the wild. However, more than half (59.1%) of the consumers reported eating venison only one to five times in their life or only once or twice a year. These findings indicate that a high percentage of the United States population engages in hunting and/or venison consumption. If CWD continues to spread to more areas across the country, a substantial number of people could potentially be exposed to the infectious agent.
Title: Experimental oral transmission of chronic wasting disease (CWD) to red deer (Cervus elaphus elaphus): early detection and late stage distribution of protease-resistant protein (PrP-res)
Balachandran, A - CANADIAN FOOD INSPCTN AG Harrington, Noel - CANADIAN FOOD INSPCTN AG Algire, James - CANADIAN FOOD INSPCTN AG Souyrine, Andre - CANADIAN FOOD INSPCTN AG Orourke, Katherine Spraker, Terry - COLORADO ST UNIV
Submitted to: Canadian Journal of Veterinary Research Publication Type: Peer Reviewed Journal Publication Acceptance Date: December 1, 2008 Publication Date: N/A
Interpretive Summary: Farmed cervids may be exposed to the prion disorder chronic wasting disease through contact with free ranging or farmed infected Rocky Mountain elk, white tailed deer, mule deer, or moose. This is the first report of experimental transmission of chronic wasting disease to red deer, an economically important agricultural commodity in parts of North America. Brain tissue from infected Rocky Mountain elk was administered by the oral route of red deer. Deer were examined at 18 months after infection for evidence of abnormal prion protein, the marker for the disease. The abnormal protein was found throughout the brain, spinal cord and lymphoid tissues, with variable distribution in other organ systems. This finding confirms the potential susceptibility of this species to disease under natural conditions and the reliability of the current testing format for identifying the abnormal protein in the tissues routinely collected in surveillance programs. The widespread distribution of the abnormal protein in red deer indicates the potential for shedding of the agent into the environment. Technical Abstract: Chronic wasting disease CWD is the transmissible spongiform encephalopathy or prion disease of wild and farmed cervid ruminants, including Rocky Mountain elk (Cervus elaphus nelsoni), white tailed deer (Odocoileus virginianus), mule deer (Odocoileus hemionus), or moose (Alces alces). Reliable data on the susceptibility of other farmed cervid species, the distribution of the abnormal prion protein marker in brain and lymphoid tissues collected in surveillance programs, and the role of prion genotype are necessary for design of control programs for CWD in farmed cervids. In this study, red deer (Cervus elaphus elaphus) were exposed to the prion agent by oral administration of brain homogenates from infected Rocky Mountain elk. Antemortem testing was performed at 7 months post infection and the deer were euthanized when clinical disease was observed at approximately 18 months after infection. The abnormal prion protein was assayed by immunohistochemistry, enzyme linked immunosorbent assay and western blot. Abnormal prion protein was found in the spinal cord, brainstem, cerebellum, midbrain, thalamus, and cerebrum in all 4 infected red deer. Most of the lymph nodes throughout the body were positive for abnormal prion proteins. Abnromal prion protein was observed in some additional peripheral tissues in some but not all of the deer. In particular, most areas of the gastrointestinal tract were positive for abnormal prions, although the salivary glands were rarely positive. This study demonstrates the potential for oral transmission of chronic wasting disease to red deer and confirms the usefulness of the current testing methods for post mortem diagnosis of the disease in this species.
Oral transmission and early lymphoid tropism of chronic wasting disease PrPres in mule deer fawns (Odocoileus hemionus )
Christina J. Sigurdson1, Elizabeth S. Williams2, Michael W. Miller3, Terry R. Spraker1,4, Katherine I. O'Rourke5 and Edward A. Hoover1
Mule deer fawns (Odocoileus hemionus) were inoculated orally with a brain homogenate prepared from mule deer with naturally occurring chronic wasting disease (CWD), a prion-induced transmissible spongiform encephalopathy. Fawns were necropsied and examined for PrP res, the abnormal prion protein isoform, at 10, 42, 53, 77, 78 and 80 days post-inoculation (p.i.) using an immunohistochemistry assay modified to enhance sensitivity. PrPres was detected in alimentary-tract-associated lymphoid tissues (one or more of the following: retropharyngeal lymph node, tonsil, Peyer's patch and ileocaecal lymph node) as early as 42 days p.i. and in all fawns examined thereafter (53 to 80 days p.i.). No PrPres staining was detected in lymphoid tissue of three control fawns receiving a control brain inoculum, nor was PrPres detectable in neural tissue of any fawn. PrPres-specific staining was markedly enhanced by sequential tissue treatment with formic acid, proteinase K and hydrated autoclaving prior to immunohistochemical staining with monoclonal antibody F89/160.1.5. These results indicate that CWD PrP res can be detected in lymphoid tissues draining the alimentary tract within a few weeks after oral exposure to infectious prions and may reflect the initial pathway of CWD infection in deer. The rapid infection of deer fawns following exposure by the most plausible natural route is consistent with the efficient horizontal transmission of CWD in nature and enables accelerated studies of transmission and pathogenesis in the native species.
These results indicate that mule deer fawns develop detectable PrP res after oral exposure to an inoculum containing CWD prions. In the earliest post-exposure period, CWD PrPres was traced to the lymphoid tissues draining the oral and intestinal mucosa (i.e. the retropharyngeal lymph nodes, tonsil, ileal Peyer's patches and ileocaecal lymph nodes), which probably received the highest initial exposure to the inoculum. Hadlow et al. (1982) demonstrated scrapie agent in the tonsil, retropharyngeal and mesenteric lymph nodes, ileum and spleen in a 10-month-old naturally infected lamb by mouse bioassay. Eight of nine sheep had infectivity in the retropharyngeal lymph node. He concluded that the tissue distribution suggested primary infection via the gastrointestinal tract. The tissue distribution of PrPres in the early stages of infection in the fawns is strikingly similar to that seen in naturally infected sheep with scrapie. These findings support oral exposure as a natural route of CWD infection in deer and support oral inoculation as a reasonable exposure route for experimental studies of CWD.
see full text ;
Wednesday, January 07, 2009
CWD to tighten taxidermy rules Hunters need to understand regulations
ALSO, NOTE MINERAL LICKS A POSSIBLE SOURCE AND TRANSMISSION MODE FOR CWD ;
CWD, GAME FARMS, BAITING, AND POLITICS
Published Online 26 January 2006 Science 24 February 2006: Vol. 311 no. 5764 p. 1117 DOI: 10.1126/science.1122864 •Brevia
Prions in Skeletal Muscles of Deer with Chronic Wasting Disease
Rachel C. Angers1,*, Shawn R. Browning1,*†, Tanya S. Seward2, Christina J. Sigurdson4,‡, Michael W. Miller5, Edward A. Hoover4 and Glenn C. Telling1,2,3,§ + Author Affiliations
The emergence of chronic wasting disease (CWD) in deer and elk in an increasingly wide geographic area, as well as the interspecies transmission of bovine spongiform encephalopathy to humans in the form of variant Creutzfeldt Jakob disease, have raised concerns about the zoonotic potential of CWD. Because meat consumption is the most likely means of exposure, it is important to determine whether skeletal muscle of diseased cervids contains prion infectivity. Here bioassays in transgenic mice expressing cervid prion protein revealed the presence of infectious prions in skeletal muscles of CWD-infected deer, demonstrating that humans consuming or handling meat from CWD-infected deer are at risk to prion exposure.
Received for publication 21 November 2005. Accepted for publication 13 January 2006.
Journal of Virology, September 2009, p. 9608-9610, Vol. 83, No. 18 0022-538X/09/$08.00+0 doi:10.1128/JVI.01127-09 Copyright © 2009, American Society for Microbiology. All Rights Reserved.
Prion Infectivity in Fat of Deer with Chronic Wasting Disease
Brent Race,# Kimberly Meade-White,# Richard Race, and Bruce Chesebro* Rocky Mountain Laboratories, 903 South 4th Street, Hamilton, Montana 59840
Received 2 June 2009/ Accepted 24 June 2009
ABSTRACT Top ABSTRACT TEXT REFERENCES
Chronic wasting disease (CWD) is a neurodegenerative prion disease of cervids. Some animal prion diseases, such as bovine spongiform encephalopathy, can infect humans; however, human susceptibility to CWD is unknown. In ruminants, prion infectivity is found in central nervous system and lymphoid tissues, with smaller amounts in intestine and muscle. In mice, prion infectivity was recently detected in fat. Since ruminant fat is consumed by humans and fed to animals, we determined infectivity titers in fat from two CWD-infected deer. Deer fat devoid of muscle contained low levels of CWD infectivity and might be a risk factor for prion infection of other species.
The highest risk of human contact with CWD might be through exposure to high-titer CNS tissue through accidental skin cuts or corneal contact at the time of harvest and butchering. However, the likelihood of a human consuming fat infected with a low titer of the CWD agent is much higher. It is impossible to remove all the fat present within muscle tissue, and fat consumption is inevitable when eating meat. Of additional concern is the fact that meat from an individual deer harvested by a hunter is typically consumed over multiple meals by the same group of people. These individuals would thus have multiple exposures to the CWD agent over time, which might increase the chance for transfer of infection.
In the Rocky Mountain region of North America, wild deer are subject to predation by wolves, coyotes, bears, and mountain lions. Although canines such as wolves and coyotes are not known to be susceptible to prion diseases, felines definitely are susceptible to BSE (9) and might also be infected by the CWD agent. Deer infected with the CWD agent are more likely to be killed by predators such as mountain lions (11). Peripheral tissues, including lymph nodes, muscle, and fat, which harbor prion infectivity are more accessible for consumption than CNS tissue, which has the highest level of infectivity late in disease. Therefore, infectivity in these peripheral tissues may be important in potential cross-species CWD transmissions in the wild.
The present finding of CWD infectivity in deer fat tissue raises the possibility that prion infectivity might also be found in fat tissue of other infected ruminants, such as sheep and cattle, whose fat and muscle tissues are more widely distributed in both the human and domestic-animal food chains. Although the infectivity in fat tissues is low compared to that in the CNS, there may be significant differences among species and between prion strains. Two fat samples from BSE agent-infected cattle were reported to be negative by bioassay in nontransgenic RIII mice (3, 6). However, RIII mice are 10,000-fold-less sensitive to BSE agent infection than transgenic mice expressing bovine PrP (4). It would be prudent to carry out additional infectivity assays on fat from BSE agent-infected cattle and scrapie agent-infected sheep using appropriate transgenic mice or homologous species to determine the risk from these sources.
Thursday, August 28, 2008
CWD TISSUE INFECTIVITY brain, lymph node, blood, urine, feces, antler velvet and muscle
Sunday, April 12, 2009
CWD UPDATE Infection Studies in Two Species of Non-Human Primates and one Environmental reservoir infectivity study and evidence of two strains
Sunday, December 06, 2009
Detection of Sub-Clinical CWD Infection in Conventional Test-Negative Deer Long after Oral Exposure to Urine and Feces from CWD+ Deer
Wednesday, March 18, 2009
Detection of CWD Prions in Urine and Saliva of Deer by Transgenic Mouse Bioassay
Tuesday, June 16, 2009
Infectious Prions in Pre-Clinical Deer and Transmission of Chronic Wasting Disease Solely by Environmental Exposure
Wednesday, October 14, 2009
Detection of protease-resistant cervid prion protein in water from a CWD-endemic area
AS THE CROW FLIES, SO DOES CWD
Sunday, November 01, 2009
American crows (Corvus brachyrhynchos) and potential spreading of CWD through feces of digested infectious carcases