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Title: Experimental oral transmission of chronic wasting disease to reindeer (Rangifer tarandus tarandus)

Author
item MITCHELL, G - Canadian Food Inspection Agency
item SIGURDSON, C - University Of California
item O'Rourke, Katherine
item ALGIRE, J - Canadian Food Inspection Agency
item HARRINGTON, N - Canadian Food Inspection Agency
item WALTHER, I - Canadian Food Inspection Agency
item SPRAKER, T - Colorado State University
item BALACHANDRAN, A - Canadian Food Inspection Agency

Submitted to: PLoS Pathogens
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/12/2012
Publication Date: 6/19/2012
Citation: Mitchell, G.B., Sigurdson, C.J., Orourke, K.I., Algire, J., Harrington, N.P., Walther, I., Spraker, T.R., Balachandran, A. 2012. Experimental oral transmission of chronic wasting disease to reindeer (Rangifer tarandus tarandus). PLoS Pathogens. 7(6)e39055.

Interpretive Summary: Chronic wasting disease (CWD) is a fatal transmissible neurodegenerative disease known to affect wild and farmed populations of elk, white-tailed deer, mule deer and moose. Similar to related diseases in humans (Creutzfeldt-Jakob disease), cattle (bovine spongiform encephalopathy) and sheep (scrapie), CWD is caused by the accumulation of misfolded prion protein aggregates in the brain leading to the progressive manifestation of neurological deficits. Although CWD has not been reported in reindeer or caribou, their habitat may overlap with cervid species which are infected with CWD. Here we examine whether CWD taken from infected elk or white-tailed deer is able to infect reindeer by the oral route. We demonstrate that CWD from white-tailed deer is transmissible to reindeer and that the prion genotype of reindeer may be an important determinant of CWD susceptibility in this species.

Technical Abstract: Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy or TSE of wild and farmed cervid ruminants in the North America, including white tailed, black tailed and mule deer, Rocky Mountain elk and Shira's moose. CWD, like the other TSEs, is associated with accumulation of an abnormal isoform of the normal prion protein. The sequence of the gene encoding the normal prion protein varies slightly among individuals and polymorphisms at codon 96 in white tailed deer, 132 in Rocky Mountain elk, and 226 in mule deer are associated with either prolonged incubation times or relative resistance to disease, evidenced by reduced prevalence in exposed populations. The susceptibility of reindeer, a species of considerable cultural and economic significance in the the far northern regions of North America, is unknown, although the range of some subspecies of reindeer overlaps with that of highly susceptible species. In this experiment, domestic reindeer (Rangifer tarandus tarandus) were exposed to the CWD agent by oral dosing with brain homogenate from infected elk or white tailed deer. Retrospective analysis of the gene encoding the normal prion protein demonstrated polymorphisms at 4 sites with the entire research group. Two of the reindeer developed clinical signs consistent with CWD by 2 years of age and post mortem analysis demonstrated extensive distribution of the abnormal form of the prion protein in neural and extraneural tissue, consistent with findings of CWD in other cervid species. Four reindeer survived past two years of age and one was alive at the time of the writing of the manuscript, 58 months after exposure. All 4 shared at least one prion gene polymorphism, suggesting that the prion genotype of reindeer may be an important determinant in CWD susceptibility in this species.