White-tailed Deer are Susceptible to Scrapie by Natural Route of Infection
Jodi D. Smith, Justin J. Greenlee, and Robert A. Kunkle; Virus and Prion Research Unit, National Animal Disease Center, USDA-ARS
Interspecies transmission studies afford the opportunity to better understand the potential host range and origins of prion diseases. Previous experiments demonstrated that white-tailed deer are susceptible to sheep-derived scrapie by intracranial inoculation. The purpose of this study was to determine susceptibility of white-tailed deer to scrapie after a natural route of exposure. Deer (n=5) were inoculated by concurrent oral (30 ml) and intranasal (1 ml) instillation of a 10% (wt/vol) brain homogenate derived from a sheep clinically affected with scrapie. Non-inoculated deer were maintained as negative controls. All deer were observed daily for clinical signs. Deer were euthanized and necropsied when neurologic disease was evident, and tissues were examined for abnormal prion protein (PrPSc) by immunohistochemistry (IHC) and western blot (WB). One animal was euthanized 15 months post-inoculation (MPI) due to an injury. At that time, examination of obex and lymphoid tissues by IHC was positive, but WB of obex and colliculus were negative. Remaining deer developed clinical signs of wasting and mental depression and were necropsied from 28 to 33 MPI. Tissues from these deer were positive for scrapie by IHC and WB. Tissues with PrPSc immunoreactivity included brain, tonsil, retropharyngeal and mesenteric lymph nodes, hemal node, Peyer’s patches, and spleen. This work demonstrates for the first time that white-tailed deer are susceptible to sheep scrapie by potential natural routes of inoculation. In-depth analysis of tissues will be done to determine similarities between scrapie in deer after intracranial and oral/intranasal inoculation and chronic wasting disease resulting from similar routes of inoculation.
see full text ; http://www.usaha.org/Portals/6/Repo...l-2010.pdf
White-tailed deer are susceptible to the agent of sheep scrapie by intracerebral inoculation
It is unlikely that CWD will be eradicated from free-ranging cervids, and the disease is likely to continue to spread geographically . However, the potential that white-tailed deer may be susceptible to sheep scrapie by a natural route presents an additional confounding factor to halting the spread of CWD. This leads to the additional speculations that
1) infected deer could serve as a reservoir to infect sheep with scrapie offering challenges to scrapie eradication efforts and
2) CWD spread need not remain geographically confined to current endemic areas, but could occur anywhere that sheep with scrapie and susceptible cervids cohabitate.
This work demonstrates for the first time that white-tailed deer are susceptible to sheep scrapie by intracerebral inoculation with a high attack rate and that the disease that results has similarities to CWD. These experiments will be repeated with a more natural route of inoculation to determine the likelihood of the potential transmission of sheep scrapie to white-tailed deer. If scrapie were to occur in white-tailed deer, results of this study indicate that it would be detected as a TSE, but may be difficult to differentiate from CWD without in-depth biochemical analysis. http://www.ncbi.nlm.nih.gov/pmc/art...ool=pubmed http://chronic-wasting-disease.blog...le-to.html
Wednesday, February 16, 2011
SCRAPIE TRANSMISSION TO CHIMPANZEES
IN CONFIDENCE http://scrapie-usa.blogspot.com/201...on-to.html
PO-039: A comparison of scrapie and chronic wasting disease in white-tailed deer
Justin Greenlee, Jodi Smith, Eric Nicholson US Dept. Agriculture; Agricultural Research Service, National Animal Disease Center; Ames, IA USA
Interspecies transmission studies afford the opportunity to better understand the potential host range and origins of prion diseases. The purpose of these experiments was to determine susceptibility of white-tailed deer (WTD) to scrapie and to compare the resultant clinical signs, lesions, and molecular profiles of PrPSc to those of chronic wasting disease (CWD). We inoculated WTD intracranially (IC; n = 5) and by a natural route of exposure (concurrent oral and intranasal (IN); n = 5) with a US scrapie isolate.
All deer were inoculated with a 10% (wt/vol) brain homogenate from sheep with scrapie (1ml IC, 1 ml IN, 30 ml oral). All deer inoculated by the intracranial route had evidence of PrPSc accumulation. PrPSc was detected in lymphoid tissues as early as 7 months-post-inoculation (PI) and a single deer that was necropsied at 15.6 months had widespread distribution of PrPSc highlighting that PrPSc is widely distributed in the CNS and lymphoid tissues prior to the onset of clinical signs. IC inoculated deer necropsied after 20 months PI (3/5) had clinical signs, spongiform encephalopathy, and widespread distribution of PrPSc in neural and lymphoid tissues.
The results of this study suggest that there are many similarities in the manifestation of CWD and scrapie in WTD after IC inoculation including early and widespread presence of PrPSc in lymphoid tissues, clinical signs of depression and weight loss progressing to wasting, and an incubation time of 21-23 months. Moreover, western blots (WB) done on brain material from the obex region have a molecular profile similar to CWD and distinct from tissues of the cerebrum or the scrapie inoculum. However, results of microscopic and IHC examination indicate that there are differences between the lesions expected in CWD and those that occur in deer with scrapie: amyloid plaques were not noted in any sections of brain examined from these deer and the pattern of immunoreactivity by IHC was diffuse rather than plaque-like.
After a natural route of exposure, 100% of WTD were susceptible to scrapie. Deer developed clinical signs of wasting and mental depression and were necropsied from 28 to 33 months PI. Tissues from these deer were positive for PrPSc by IHC and WB. Similar to IC inoculated deer, samples from these deer exhibited two different molecular profiles: samples from obex resembled CWD whereas those from cerebrum were similar to the original scrapie inoculum. On further examination by WB using a panel of antibodies, the tissues from deer with scrapie exhibit properties differing from tissues either from sheep with scrapie or WTD with CWD. Samples from WTD with CWD or sheep with scrapie are strongly immunoreactive when probed with mAb P4, however, samples from WTD with scrapie are only weakly immunoreactive. In contrast, when probed with mAb’s 6H4 or SAF 84, samples from sheep with scrapie and WTD with CWD are weakly immunoreactive and samples from WTD with scrapie are strongly positive. This work demonstrates that WTD are highly susceptible to sheep scrapie, but on first passage, scrapie in WTD is differentiable from CWD. http://www.landesbioscience.com/jou...trains.pdf
PO-081: Chronic wasting disease in the cat— Similarities to feline spongiform encephalopathy (FSE) http://www.landesbioscience.com/jou...hology.pdf http://chronic-wasting-disease.blog...n2012.html
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*** Spraker suggested an interesting explanation for the occurrence of CWD. The deer pens at the Foot Hills Campus were built some 30-40 years ago by a Dr. Bob Davis. At or abut that time, allegedly, some scrapie work was conducted at this site. When deer were introduced to the pens they occupied ground that had previously been occupied by sheep.
(PLEASE NOTE SOME OF THESE OLD UK GOVERNMENT FILE URLS ARE SLOW TO OPEN, AND SOMETIMES YOU MAY HAVE TO CLICK ON MULTIPLE TIMES, PLEASE BE PATIENT, ANY PROBLEMS PLEASE WRITE ME PRIVATELY, AND I WILL TRY AND FIX OR SEND YOU OLD PDF FILE...TSS) http://collections.europarchive.org.../tab01.pdf