2011 Annual Report
In Objective 1, Assess cross-species transmissibility of transmissible spongiform encephalopathies (TSEs) in livestock and wildlife, numerous experiments assessing the susceptibility of various TSEs in different host species were conducted. Most notable is deer inoculated with scrapie, which exhibits similarities to chronic wasting disease (CWD) in deer suggestive of sheep scrapie as an origin of CWD.
In Objective 2, Investigate the pathobiology of TSEs in natural and secondary hosts, deer were inoculated with CWD-infected blood. Several animals developed clinical signs, a result consistent with CWD infectivity in blood. Also, biochemical strain typing commonly used for rodent models of TSE was investigated to assess the importance of genetic variability in natural hosts and how to apply these methods to natural hosts.
Objective 3, Investigate pathogenesis and antemortem detection of bovine spongiform encephalopathy (BSE), involves several different research areas. Our results in genetic susceptibility of BSE support the now widely accepted conclusion that atypical BSE is a spontaneous TSE in cattle. This has important implications for the ruminant feed ban, food safety, and our understanding of the origins of BSE. Also as part of Obj. 3, we identified the first recognized case of genetic BSE where a natural case of BSE was identified in an animal containing a polymorphism analogous to a human polymorphism that causes a genetic TSE. Bovine spongiform encephalopathy has long been believed to only be a feed-borne disease. Together, our results show for the first time the presence of three different etiologies for BSE as are known to occur in humans. As part of our investigation, classical, and atypical BSE isolates were inoculated into cattle. Upon completion, this work will represent the first thorough comparison of domestic and international BSE isolates, including both classical and atypical BSE. An antemortem diagnostic technique based upon retinal function was developed and is routinely applied to experimental animals on site. This technique detects a TSE before the onset of clinical signs. Work is ongoing to increase the number of animals containing the E211K polymorphism, a potential cause of genetic BSE; this will provide the only means by which to prove the novel allele may cause BSE. The unusual E211K BSE material has also been successfully amplified in one of these animals.
Objective 4, Develop a method to detect CNS tissue contamination on carcasses, resulted in a successful method that may be applied through adaptation of existing technology currently used to detect fecal contamination on carcasses.
In Objective 5, Determine effective methods to inactivate TSE agents in agricultural settings, compounds applicable to agricultural settings were evaluated; the results are being prepared for publication. As part of this objective, a natural host model for assessing inactivation was developed. Despite experimental success the model is not suitable due to incubation time.
Hamir, A.N., Greenlee, J.J., Stanton, T.B., Smith, J.D., Doucette, S., Kunkle, R.A., Stasko, J.A., Richt, J.A., Kehrli, Jr., M.E. 2011. Experimental inoculation of raccoons (Procyon lotor) with Spiroplasma mirum and transmissible mink encephalopathy (TME). Canadian Journal of Veterinary Research. 75(1):18–24.
Hamir, A.N., Greenlee, J.J., Nicholson, E.M., Kunkle, R.A., Richt, J.A., Miller, J.M., Hall, M. 2011. Experimental transmission of chronic wasting disease (CWD) from elk and white-tailed deer to fallow deer by intracerebral route: final report. Canadian Journal of Veterinary Research. 75(2):152-156.
Smith, J.D., Hamir, A.N., Greenlee, J.J. 2011. Cartilaginous metaplasia in the sclera of Suffolk sheep. Veterinary Pathology. 48(4):827-829. Loiacono, C.M., Beckwith, N., Kunkle, R.A., Orcutt, D., Hall, S.M. 2010. Detection of PrPSc in formalin-fixed, paraffin embedded tissue by Western blot differentiates classical scrapie, Nor98 scrapie, and bovine spongiform encephalopathy. Journal of Veterinary Diagnostic Investigation. 22(5):684-689.
Hamir, A.N., Kehrli, Jr., M.E., Kunkle, R.A., Greenlee, J.J., Nicholson, E.M., Richt, J.A., Miller, J.M., Cutlip, R.C. 2011. Experimental interspecies transmission studies of the transmissible spongiform encephalopathies to cattle: comparison to bovine spongiform encephalopathy in cattle. Journal of Veterinary Diagnostic Investigation. 23(3):407-420.
Nicholson, E.M. 2011. Enrichment of PrPSc in formalin-fixed, paraffin-embedded tissues prior to analysis by Western blot. Journal of Veterinary Diagnostic Investigation. 23(4):790-792.