close

Privacy guaranteed - Your email is not shared with anyone.

Excretion of transmissible spongiform encephalopathy infectivity in urine

Discussion in 'Wildlife Diseases' started by terry, Aug 1, 2008.

  1. terry

    terry

    Messages:
    1,324
    Likes Received:
    8
    Location:
    Bacliff, TEXAS USA
    -------------------- BSE-L@LISTS.AEGEE.ORG --------------------

    DOI: 10.3201/eid1409.080259

    Suggested citation for this article: Gregori L, Kovacs GG, Alexeeva I, Budka H, Rohwer RG.

    Excretion of transmissible spongiform encephalopathy infectivity in urine.

    Emerg Infect Dis. 2008 Sep; [Epub ahead of print]

    Excretion of Transmissible Spongiform Encephalopathy Infectivity in Urine Luisa Gregori, Gabor G. Kovacs, Irina Alexeeva, Herbert Budka, and Robert G. Rohwer Author affiliations: Veterans Affairs Medical Center, Baltimore, Maryland, USA (L. Gregori, I. Alexeeva, R.G. Rohwer); University of Maryland, Baltimore (L. Gregori, R.G. Rohwer); and Medical University of Vienna, Vienna, Austria (G.G. Kovacs, H. Budka) The route of transmission of most naturally acquired transmissible spongiform encephalopathy (TSE) infections remains speculative. To investigate urine as a potential source of TSE exposure, we used a sensitive method for detection and quantitation of TSE infectivity. Pooled urine collected from 22 hamsters showing clinical signs of 263K scrapie contained 3.8 ± 0.9 infectious doses/mL of infectivity. Titration of homogenates of kidneys and urinary bladders from the same animals gave concentrations 20,000-fold greater. Histologic and immunohistochemical examination of these same tissues showed no indications of inflammatory or other pathologic changes except for occasional deposits of diseaseassociated prion protein in kidneys. Although the source of TSE infectivity in urine remains unresolved, these results establish that TSE infectivity is excreted in urine and may thereby play a role in the horizontal transmission of natural TSEs. The results also indicate potential risk for TSE transmission from human urine-derived hormones and other medicines.

    snip...

    Discussion Anticipating that the titer of scrapie infectivity in excreted urine would be low, we measured concentration by using limiting dilution titration, a method with which we have extensive experience quantitating TSE infectivity in blood and blood components. In a limiting dilution titration, all animals in the bioassay are inoculated with the highest concentration of inoculum that is tolerated by the intracranial (most efficient) route. Infectivity assorts randomly into the inoculated animals; provided that at least some, but not all, of the animals are infected, the concentration can be calculated from the Poisson distribution of the infections (1). The method is highly sensitive and far more precise than other methods of TSE titration. We considered concentrating the urine before bioassay, but to circumvent uncertainties about the recovery of endogenous infectivity, we decided to inject the urine as collected. We found TSE infectivity in the urine of hamsters that had no evidence of kidney or bladder inflammation. In contrast, Seeger et al. did not detect infectivity in the urine of scrapieinfected mice (11) unless the mice were also affected by nephritis, in which case they found low levels of infectivity. Whether the bioassay they used was capable of detecting infectivity at the Page 9 of 16 concentration we observed for hamsters is not clear. If it was not capable, then detection of infectivity in mice with nephritis implies a higher concentration of infectivity in urine excreted by a nephritic kidney. In another study, urine and feces from deer with chronic wasting disease failed to demonstrate infectivity when orally given to the same susceptible species (17). Although usually an inefficient route of inoculation, the oral route did successfully transmit chronic wasting disease infectivity in saliva. The authors identified several possible reasons for the unsuccessful transmission by excreta, including incubation time, genotype, or sample size. In our experiments, cross-contamination by feces can not be excluded as a source of infectivity. Although the metabolism cage effectively separated urine and feces, some contact is possible because of the anatomy of the hamster. Protein misfolding cyclic amplification uses sonication to generate PrPres and infectivity in vitro. Although we routinely disperse all samples by ultrasonication before injection, our conditions are much harsher than those used to generate PrPres de novo (18) and do not support protein misfolding cyclic amplification of PrPres, or presumably infectivity (L. Gregori and R.G. Rohwer, unpub. data). The kidney and bladder titers were far greater than expected compared with findings of historical studies in which, with only rare exceptions (19-21), most attempts at transmission have been unsuccessful. These titers cannot be explained by the infectivity in residual blood (10 ID/mL) (1,2). In addition, we observed PrPd in the kidneys of scrapie-infected animals that had no indications of tissue inflammation. Heikenwalder et al. found PrPd staining within follicular infiltrates only in kidneys of mice affected by nephritis and not in control mice with noncomplicated scrapie (12). These data together with those by Seeger et al. (11) suggested that renal inflammation might be a prerequisite for TSE infectivity in renal tissue and its excretion in urine. In contrast, our results indicate that renal inflammation is not necessary for the deposition of PrPd in kidneys or for excretion of infectivity. One interpretation is that nephritis enhances the accumulation of PrPd at sites of inflammation, consistent with the excretion of higher levels of infectivity inferred above for this same condition (11). Two studies of scrapie in naturally and experimentally infected sheep reported PrPd depositions in the renal papillae (22) and in the intraepithelial cortex, medulla, and papillae (23). Similar to our findings, both studies indicated that not all scrapie tissues examined were positive Page 10 of 16 for PrPd. In chronic wasting disease, PrPd staining was uniqu ly localized in the ectopic lymphoid follicle of the kidney of a whitetail deer (24). All studies indicated either no changes (23,24) or mild to no inflammatory changes of the kidney (23). Thus, our histologic and immunohistochemical results for scrapie-infected hamsters are consistent with results found for sheep and deer and suggest that under normal conditions TSE diseases do not have concomitant inflammatory changes in the kidney. That urine titer is similar to that of plasma suggests that urine infectivity may originate from blood (25), but how the infectivity would be excreted is not clear. In general, proteins >40 kDa are not excreted and smaller proteins crossing the glomeruli are reabsorbed in the renal tubule and returned to the blood. If TSE infectivity is particulate (>40 kDa), its presence in urine might indicate abnormalities in renal filtration, perhaps related to the accumulation of PrPd in the collecting tubules of the medulla. The accumulation of immunoglobulins in the urine of TSEinfected hamsters and humans may also indicate malfunction of the urinary system (9,26). Excretion of a small C-terminal fragment of the normal cellular form of the prion protein in urine of infected and noninfected animals has been reported (27), but PrPres or PrPd forms can only be inferred from the presence of infectivity. Nevertheless, excretion of proteins similar to PrPres or PrPd forms has been documented. Follicle-stimulating hormone is a glycosylated protein of 203 amino acids organized mostly as a â-sheet, which bears some remarkable similarities to â-rich forms of the prion protein. Follicle-stimulating and several similar hormones are excreted in urine at great enough concentration to be extracted commercially. Alternatively, TSE infectivity may be excreted by processes analogous to those responsible for the low-level virurias that occur during infections of the nervous system by mumps, measles, and West Nile virus (28-30). To the extent that results from the hamster model can be generalized to other TSE infections (and it has so far proven highly predictive), then even the very low concentrations of infectivity measured here could result in substantial environmental contamination. Several liters of urine and several thousand doses of TSE infectivity may be excreted daily over the course of the illness; even higher titers might be excreted by an animal with nephritis. The high stability of TSE infectivity would account for its persistence in pasture years after infected animals are removed (31). Recent studies have shown that infectivity that is adsorbed and immobilized by soil minerals (32) can still infect hamsters by oral exposure 29 months later (33). Our study also Page 11 of 16 warns of a possible risk from TSE contamination to fertility hormones and other medicinal products extracted from human urine.

    Acknowledgments

    snip...full text ;

    http://www.cdc.gov/eid/content/14/9/pdfs/08-0259.pdf


    -------------------- BSE-L@LISTS.AEGEE.ORG --------------------


    Wednesday, June 11, 2008

    Transmission and Detection of Prions in Feces

    The Journal of Infectious Diseases 2008;198:81–89 © 2008 by the Infectious Diseases Society of America. All rights reserved. 0022-1899/2008/19801-0015$15.00 DOI: 10.1086/588193

    snip...

    P04.61 Survival of PrPSc during Simulated Wastewater Treatment Processes

    Pedersen, J1; Hinckley, G1; McMahon, K2; McKenzie, D3; Aiken, JM3 1University of Wisconsin, Soil Science/Civil and Environmental Engineering, USA; 2University of Wisconsin, Civil and Environmental Engineering, USA; 3University of Wisconsin, Comparative Biosciences, USA

    Concern has been expressed that prions could enter wastewater treatment systems through sewer and/or septic systems (e.g., necropsy laboratories, rural meat processors, private game dressing) or through leachate from landfills that have received TSE-contaminated material. Prions are highly resistant to degradation and many disinfection procedures raising concern that they could survive conventional wastewater treatment. Here, we report the results of experiments examining the partitioning and survival of PrPSc during simulated wastewater treatment processes including activated and mesophilic anaerobic sludge digestion. We establish that PrPSc can be efficiently extracted from activated and anaerobic digester sludges with 1% sodium dodecyl sulfate, 10% sodium undecyl sulfate, and 1% sodium N-lauryl sarcosinate. Activated sludge digestion does not result in significant degradation of PrPSc. The protein partitions strongly to the activated sludge solids and is expected to enter biosolids treatment processes. A large fraction of PrPSc survived simulated mesophilic anaerobic sludge digestion. Our results suggest that if prions were to enter municipal waste water treatment systems, most of the agent would partition to activated sludge solids, survive mesophilic anaerobic digestion, and be present in treated biosolids. Land application of biosolids containing prions could represent a route for their unintentional introduction into the environment. Our results argue for excluding inputs of prions to municipal wastewater treatment facilities that would result in unacceptable risk of prion disease transmission via contaminated biosolids.


    http://www.prion2007.com/pdf/Prion Book of Abstracts.pdf


    Oral Transmissibility of Prion Disease Is Enhanced by Binding to Soil Particles

    Christopher J. Johnson1,2, Joel A. Pedersen3, Rick J. Chappell4, Debbie McKenzie2, Judd M. Aiken1,2*

    Soil may serve as an environmental reservoir for prion infectivity and contribute to the horizontal transmission of prion diseases (transmissible spongiform encephalopathies [TSEs]) of sheep, deer, and elk. TSE infectivity can persist in soil for years, and we previously demonstrated that the disease-associated form of the prion protein binds to soil particles and prions adsorbed to the common soil mineral montmorillonite (Mte) retain infectivity following intracerebral inoculation. …

    In conclusion, our results provide compelling support for the hypothesis that soil serves as a biologically relevant reservoir of TSE infectivity. Our data are intriguing in light of reports that naïve animals can contract TSEs following exposure to presumably low doses of agent in the environment [5,7*9]. We find that Mte enhances the likelihood of TSE manifestation in cases that would otherwise remain subclinical (Figure 3B and 3C), and that prions bound to soil are orally infectious (Figure 5). Our results demonstrate that adsorption of TSE agent to inorganic microparticles and certain soils alter transmission efficiency via the oral route of exposure. full text is here:

    http://pathogens.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.ppat.0030093

    http://pathogens.plosjournals.org/perlserv/?request=get-pdf&file=10.1371_journal.ppat.0030093-L.pdf

    http://pathogens.plosjournals.org/perlserv/?request=get-pdf&file=10.1371_journal.ppat.0030093-S.pdf

    http://lists.ifas.ufl.edu/cgi-bin/wa.exe?A2=ind0611&L=sanet-mg&T=0&F=&S=&m=1742&P=7260

    Science 14 October 2005:Vol. 310. no. 5746, pp. 324 - 326DOI: 10.1126/science.1118829 Reports

    Coincident Scrapie Infection and Nephritis Lead to Urinary Prion Excretion

    Harald Seeger,1* Mathias Heikenwalder,1* Nicolas Zeller,1 Jan Kranich,1 Petra Schwarz,1 Ariana Gaspert,2 Burkhardt Seifert,3 Gino Miele,1 Adriano Aguzzi1

    Prion infectivity is typically restricted to the central nervous and lymphatic systems of infected hosts, but chronic inflammation can expand the distribution of prions. We tested whether chronic inflammatory kidney disorders would trigger excretion of prion infectivity into urine. Urinary proteins from scrapie-infected mice with lymphocytic nephritis induced scrapie upon inoculation into noninfected indicator mice. Prionuria was found in presymptomatic scrapie-infected and in sick mice, whereas neither prionuria nor urinary PrPSc was detectable in prion-infected wild-type or PrPC-overexpressing mice, or in nephritic mice inoculated with noninfectious brain. Thus, urine may provide a vector for horizontal prion transmission, and inflammation of excretory organs may influence prion spread.

    snip...

    SEE FULL TEXT ;

    http://chronic-wasting-disease.blogspot.com/2008/04/prion-disease-of-cervids-chronic.html


    Thursday, April 03, 2008 A prion disease of cervids: Chronic wasting disease 2008 1: Vet Res. 2008 Apr 3;39(4):41

    A prion disease of cervids: Chronic wasting disease

    Sigurdson CJ.

    snip...

    *** twenty-seven CJD patients who regularly consumed venison were reported to the Surveillance Center***,

    snip...

    full text ;

    http://chronic-wasting-disease.blogspot.com/2008/04/prion-disease-of-cervids-chronic.html


    P01.47

    Quantifying the Species Barrier in Chronic Wasting Disease by a Novel in vitro Conversion Assay

    Li, L1; Coulthart, MB2; Balachandran, A3; Chakrabartty, A4; Cashman, NR1 1University of British Columbia, Brain Research Centre, Canada; 2Public Health Agency of Canada, National Microbiology Laboratory, Canada; 3Animal Diseases Research Institute, Canada Food Inspection Agency, National Reference Laboratory for Scrapie and CWD, Canada; 4Ontario Cancer Institute and Department of Medical Biophysics, University of Toronto, Canada

    Background: Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy that can affect North American cervids (deer, elk, and moose). Although the risk of CWD crossing the species barrier and causing human disease is still unknown, however, definite bovine spongiform encephalopathy (BSE) transmission to humans as variant CJD (vCJD), it would seem prudent to limit the exposure of humans to CWD.

    Aim: In view of the fact that BSE can be readily transmitted to non-bovid species, it is important to establish the species susceptibility range of CWD.

    Methods: In vitro conversion system was performed by incubation of prions with normal brain homogenates as described before, and protease K (PK) resistant PrP was determined by immunoblotting with 6H4 monoclonal prion antibody.

    Results: Our results demonstrate that PrPC from cervids (including moose) can be efficiently converted to a protease-resistant form by incubation with elk CWD prions, presumably due to sequence and structural similarities between these species. Interestingly, hamster shows a high conversion ratio by PrPCWD. Moreover, partial denaturation of substrate PrPC can apparently overcome the structural barriers between more distant species.

    Conclusions: Our work correctly predicted the transmission of CWD to a wild moose. We find a species barrier for prion protein conversion between cervids and other species, however, this barrier might be overcome if the PrPC substrate has been partially denatured in a cellular environment. Such an environment might also promote CWD transmission to non-cervid species, *** including humans. Acid/GdnHCl-treated brain PrPC was a superior substrate for the in vitro conversion than PrPC treated at physiological pH. This has implications for the process by which the prion protein is converted in disease.

    http://www.prion2007.com/pdf/Prion Book of Abstracts.pdf


    -------- Original Message --------

    Subject: DOCKET-- 03D-0186 -- FDA Issues Draft Guidance on Use of Material From Deer and Elk in Animal Feed; Availability Date: Fri, 16 May 2003 11:47:37 -0500 From: "Terry S. Singeltary Sr." To: fdadockets@oc.fda.gov

    Greetings FDA,

    i would kindly like to comment on;

    Docket 03D-0186

    full text ;

    http://madcowfeed.blogspot.com/2008/07/docket-03d-0186-fda-issues-draft.html



    Friday, August 01, 2008

    Excretion of transmissible spongiform encephalopathy infectivity in urine

    http://creutzfeldt-jakob-disease.blogspot.com/2008/08/excretion-of-transmissible-spongiform.html



    Terry S. Singeltary Sr. P.O. Box 42 Bacliff, Texas USA 77518
     
  2. terry

    terry

    Messages:
    1,324
    Likes Received:
    8
    Location:
    Bacliff, TEXAS USA
    doi:10.1016/j.febslet.2008.08.003 Copyright © 2008 Published by Elsevier B.V.

    Detection of infectious prions in urine

    Dennisse Gonzalez-Romeroa, Marcelo A. Barriaa, Patricia Leona, Rodrigo Moralesa and Claudio Soto, a,

    aGeorge and Cynthia Mitchell Center for Neurodegenerative diseases, Departments of Neurology, Neuroscience and Cell Biology and Biochemistry and Molecular Biology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0646, USA

    Received 26 July 2008; accepted 4 August 2008. Available online 13 August 2008.

    References and further reading may be available for this article. To view references and further reading you must purchase this article.

    Abstract Prions are the infectious agents responsible for prion diseases, which appear to be composed exclusively by the misfolded prion protein (PrPSc). The mechanism of prion transmission is unknown. In this study, we attempted to detect prions in urine of experimentally infected animals. PrPSc was detected in 80% of the animals studied, whereas no false positives were observed among the control animals. Semi-quantitative calculations suggest that PrPSc concentration in urine is around 10-fold lower than in blood. Interestingly, PrPSc present in urine maintains its infectious properties. Our data indicate that low quantities of infectious prions are excreted in the urine. These findings suggest that urine is a possible source of prion transmission.

    http://www.sciencedirect.com/scienc...serid=10&md5=0e87d8b5ff0021ac6f620d73268f0e38

    Detection of infectious prions in urine

    ---------------------------------------

    By Gonzalez-Romero D, Barria MA, Leon P, Morales R, Soto C. At The George and Cynthia Mitchell Center for Neurodegenerative diseases, Departments of Neurology, Neuroscience and Cell Biology and Biochemistry and Molecular Biology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0646, USA.

    Abstract -------- Prions are the infectious agents responsible for prion diseases, which appear to be composed exclusively of the misfolded prion protein (PrP(Sc)). The mechanism of prion transmission is unknown. In this study, we attempted to detect prions in urine of experimentally infected animals [hamster]. PrP(Sc) was detected in approximately 80 per cent of the animals studied, whereas no false positives were observed among the control animals. Semi-quantitative calculations suggest that PrP(Sc) concentration in urine is around 10-fold lower than in blood. Interestingly, PrP(Sc) present in urine maintains its infectious properties. Our data indicate that low quantities of infectious prions are excreted in the urine. These findings suggest that urine is a possible source of prion transmission.

    The following paragraphs are extracts from the Discussion section of this paper:

    "PrPSc in urine retains infectious properties, since injection of the agent amplified from this fluid produced a disease indistinguishable from the one induced by in vivo isolated material. Interestingly, animals [hamsters] inoculated with PrPSc amplified from the HY strain (both from brain and urine) showed a similar incubation time as those injected with the same quantity of PrPSc from sick brain. Our findings suggest that urine is a possible source of prion transmission. Since urine produced by animals potentially infected with prions is permanently released and likely concentrated in environmental samples, such as soil and grass, this route may prove very relevant for spreading of TSEs [Transmissible Spongiform Encephalopathies] in wild and captive animals such as cervids, sheep and cattle. It is known that PrPSc is highly resistant to degradation, and infectivity can survive in the environment for a long time. Recent studies have shown that PrPSc adsorbs efficiently into soil, where it remains infectious, and that both infectivity and PrPSc can stay intact in soil for long periods. Contamination of soil with urinary prions may contribute to spreading prion disease among animals, which are known to ingest large amounts of soil, including cattle, sheep and cervids. Worrisomely, the continuous excretion of urine and the extremely high resistance of prions may lead to a progressive accumulation of infectious material in the environment, with potentially catastrophic consequences in the future.

    "One of the top priorities in the prion field is to minimize further spreading of TSEs to humans or animals by limiting the exposure to contaminated material. This is a difficult problem, because prion diseases have a long clinically-silent incubation period in which infected individuals may unknowingly transmit the disease. In addition, it is possible that many individuals may remain as sub-clinical carriers during their entire life, constituting a permanent source of prions. Therefore, the development and validation of procedures to detect even the tiniest quantities of infectious material is of paramount importance. Implementation of a large scale program to screen animals at risk of infection and diagnosis of the human population requires detection of prions in easily accessible samples, such as blood or urine. Our results showing that PrPSc can be detected in urine of a large proportion of infected animals provide a promising avenue for a sensitive and non-invasive biochemical diagnosis of prion diseases. Adaptation of PMCA [protein misfolding cyclic amplification] for detection of prions in urine of naturally infected animals and humans may offer a great possibility for routine testing of prion infections."

    http://apex.oracle.com/pls/otn/f?p=..._BACK_PAGE,F2400_P1001_PUB_MAIL_ID:1000,73794

    The Journal of Infectious Diseases 2008;198:81–89 © 2008 by the Infectious Diseases Society of America. All rights reserved. 0022-1899/2008/19801-0015$15.00 DOI: 10.1086/588193 MAJOR ARTICLE Transmission and Detection of Prions in Feces Jiri G. Safar,1,2 Pierre Lessard,1 Gültekin Tamgüney,1,2 Yevgeniy Freyman,1 Camille Deering,1 Frederic Letessier,1 Stephen J. DeArmond,1,3 and Stanley B. Prusiner1,2,4

    1Institute for Neurodegenerative Diseases, Departments of 2Neurology, 3Pathology, and 4Biochemistry and Biophysics, University of California, San Francisco, San Francisco

    In chronic wasting disease (CWD) in cervids and in scrapie in sheep, prions appear to be transmitted horizontally. Oral exposure to prion-tainted blood, urine, saliva, and feces has been suggested as the mode of transmission of CWD and scrapie among herbivores susceptible to these prion diseases. To explore the transmission of prions through feces, uninoculated Syrian hamsters (SHas) were cohabitated with or exposed to the bedding of SHas orally infected with Sc237 prions. Incubation times of 140 days and a rate of prion infection of 80%–100% among exposed animals suggested transmission by feces, probably via coprophagy. We measured the disease-causing isoform of the prion protein (PrPSc) in feces by use of the conformation-dependent immunoassay, and we titrated the irradiated feces intracerebrally in transgenic mice that overexpressed SHa prion protein (SHaPrP). Fecal samples collected from infected SHas in the first 7 days after oral challenge harbored 60 ng/g PrPSc and prion titers of 106.6 ID50/g. Excretion of infectious prions continued at lower levels throughout the asymptomatic phase of the incubation period, most likely by the shedding of prions from infected Peyer patches. Our findings suggest that horizontal transmission of disease among herbivores may occur through the consumption of feces or foodstuff tainted with prions from feces of CWD-infected cervids and scrapie-infected sheep.

    Received 9 October 2007; accepted 15 November 2007; electronically published 27 May 2008.

    (See the editorial commentary by Bosque and Tyler, on pages 8–9.)

    Potential conflicts of interest: none reported.

    Financial support: National Institutes of Health (grants AG02132, AG010770, NS22786, and NS14069); G. Harold and Leila Y. Mathers Foundation; Sherman Fairchild Foundation.

    Reprints or correspondence: Dr. Stanley B. Prusiner, 513 Parnassus Ave., HSE-774, San Francisco, CA 94143-0518 (stanley@ind.ucsf.edu).

    http://www.journals.uchicago.edu/doi/abs/10.1086/588193

    http://stanford.wellsphere.com/heal...ission-and-detection-of-prions-in-feces/13816

    http://www.michigan-sportsman.com/forum/showthread.php?p=2218816

    http://creutzfeldt-jakob-disease.blogspot.com/2008/08/excretion-of-transmissible-spongiform.html

    Subject: Infectious Prions in the Saliva and Blood of Deer with Chronic Wasting Disease

    Date: October 5, 2006 at 1:45 pm PST

    Infectious Prions in the Saliva

    and Blood of Deer with Chronic

    Wasting Disease

    Candace K. Mathiason,1 Jenny G. Powers,3 Sallie J. Dahmes,4 David A. Osborn,5 Karl V. Miller,5

    Robert J. Warren,5 Gary L. Mason,1 Sheila A. Hays,1 Jeanette Hayes-Klug,1 Davis M. Seelig,1

    Margaret A. Wild,3 Lisa L. Wolfe,6 Terry R. Spraker,1,2 Michael W. Miller,6 Christina J. Sigurdson,1

    Glenn C. Telling,7 Edward A. Hoover1*

    A critical concern in the transmission of prion diseases, including chronic wasting disease (CWD) of cervids, is the potential presence of prions in body fluids. To address this issue directly, we exposed cohorts of CWD-nai¨ve deer to saliva, blood, or urine and feces from CWD-positive deer.

    We found infectious prions capable of transmitting CWD in saliva (by the oral route) and in blood (by transfusion). The results help to explain the facile transmission of CWD among cervids and prompt caution concerning contact with body fluids in prion infections.

    SNIP...

    Deer cohorts 1 (blood), 2 (saliva), and 3 (urine and feces) were electively euthanized at 18 months pi to permit whole-body examination for PrPCWD. The greatest scrutiny was directed toward those tissues previously established to have highest frequency of PrPCWD deposition in infected deer and generally regarded as the most sensitive indicators of infection- medulla oblongata and other brainstem regions, tonsil, and retropharyngeal lymph node. We found unequivocal evidence of PrPCWD in brain and lymphoid tissue of all six tonsil biopsy- positive deer in cohorts 1 (blood) and 2 (saliva), whereas all deer in cohorts 3 and 5 were negative for PrPCWD in all tissues (Table 2 and

    Figs. 1 and 2).

    The transmission of CWD by a single blood transfusion from two symptomatic and one asymptomatic CWDþ donor is important in at least three contexts: (i) It reinforces that no tissue from CWD-infected cervids can be considered free of prion infectivity; (ii) it poses the possibility of hematogenous spread of CWD, such as through insects; and (iii) it provides a basis for seeking in vitro assays sufficiently sensitive to demonstrate PrPCWD or alternate prion protein conformers in blood-one of the grails of prion biology and epidemiology.

    The identification of blood-borne prion transmission has been sought before with mixed results (9-11). Bovine spongiform encephalopathy and scrapie have been transmitted to naBve sheep through the transfer of 500 ml of blood or buffy coat white blood cells from infected sheep (12, 13). In addition, limited but compelling evidence argues for the transmission of variant Creutzfeldt-Jakob disease (vCJD) through blood from asymptomatic donors (14-16). Even in sporadic CJD, PrPres has been found in peripheral organs of some patients (17). The present work helps establish that prion diseases can be transmitted through blood.

    The presence of infectious CWD prions in saliva may explain the facile transmission of CWD. Cervid-to-cervid interactions (SOM text), especially in high density and captive situations, would be expected to facilitate salivary crosscontact (11, 18, 19). Salivary dissemination of prions may not be limited to CWD. Proteaseresistant prion protein has been demonstrated in the oral mucosa, taste buds, lingual epithelium, vomeronasal organ, and olfactory mucosa of hamsters infected with transmissible mink encephalopathy (19) and ferrets infected with CWD (20). Although no instance of CWD transmission to humans has been detected, the present results emphasize the prudence of using impervious gloves during contact with saliva or blood of cervids that may be CWD-infected.

    Environmental contamination by excreta from infected cervids has traditionally seemed the most plausible explanation for the dissemination of CWD (21). However, we could not detect PrPCWD in cohort 3 deer inoculated repeatedly with urine and feces from CWDþ deer and examined up to 18 months pi (Table 2). There are several reasons to view this negative finding cautiously, including small sample size, elective preclinical termination, and potential variation in individual susceptibility that may be associated with the 96 G/S polymorphism in the PRNP gene (7, 22). Although no genotype of white-tailed deer is resistant to CWD infection, PRNP genotypes S/S or G/S at codon 96 appear to have reduced susceptibility manifest by longer survival (7). Both deer in cohort 3 (urine and feces) were subsequently shown to be of the PRNP 96 G/S genotype. Thus, it is possible, although we think unlikely, that these deer had a prolonged incubation period (918 months pi) before the amplification of PrPCWD became detectable in tissues. Recent studies have shown that PrPres is poorly preserved after incubation with intestinal or fecal content (23, 24). Further research using cervid and surrogate cervid PrP transgenic mice (25) are indicated to continue to address the presence of infectious CWD prions in excreta of CWDþ deer and to provide a more substantial basis for reconsideration of the assumption that excreta are the chief vehicle for CWD dissemination and transmission.

    The results reported here provide a plausible basis for the efficient transmission of CWD in nature. We demonstrate that blood and saliva in particular are able to transmit CWD to naBve deer and produce incubation periods consistent with those observed in naturally acquired infections (3, 26). The time from exposure to first detection of PrPCWD by tonsil biopsy was variable-as short as 3 months but as long as 18 months (likely underestimates due to sampling frequency). The results also reinforce a cautious view of the exposure risk presented by body fluids, excreta, and all tissues from CWDþ cervids. ...

    SNIP...END

    http://www.sciencemag.org/cgi/content/abstract/314/5796/133

    http://www.sciencemag.org/

    CWD AND ENVIRONMENTAL FACTORS i.e. saliva, fecal shedding and fecal-oral transmission is likely

    http://p079.ezboard.com/fwolftracksproductionsfrm2.showMessage?topicID=592.topic

    Tuesday, August 26, 2008 CWD Stakeholder Advisory Group Wednesday, August 22, 2007 11:31 AM

    http://chronic-wasting-disease.blogspot.com/2008/08/cwd-stakeholder-advisory-group.html

    Chronic Wasting Disease CWD

    http://chronic-wasting-disease.blogspot.com/

    TSS
     

  3. Rancid Crabtree

    Rancid Crabtree

    Messages:
    416
    Likes Received:
    0
    I like to skip to the end and reap the summary.

    The results reported here provide a plausible basis for the efficient transmission of CWD in nature. We demonstrate that blood and saliva in particular are able to transmit CWD to naBve deer and produce incubation periods consistent with those observed in naturally acquired infections (3, 26). The time from exposure to first detection of PrPCWD by tonsil biopsy was variable-as short as 3 months but as long as 18 months (likely underestimates due to sampling frequency). The results also reinforce a cautious view of the exposure risk presented by body fluids, excreta, and all tissues from CWDþ cervids. ...

    My take on it: Once a deer has detectable amounts of CWD Prions, ALL PARTS of the deer can shed those prions into the environment.

    Saliva, blood, urine, feces, GUT PILES, Car kills decomposing in the woods. Natural deaths, etc. A CWD infected deer will contaminate all the environment that it is contact with for as long as it can. The big question is, Why then DO NOT 100% of the deer that come in contact with that prion rich environment contract CWD??? Why do only a minority of wild deer contract CWD? That is the big unknown and why
     
  4. Liv4Huntin'

    Liv4Huntin'

    Messages:
    1,531
    Likes Received:
    0
    Location:
    S.W. Michigan
    Perhaps some could have a longer period to show positive... incubation period. That's the really scary part.
    ~m~
     
  5. Liv4Huntin'

    Liv4Huntin'

    Messages:
    1,531
    Likes Received:
    0
    Location:
    S.W. Michigan
    Many thanks for your research, reporting, and vigilance.
    ~m~