Submitted to: Canadian Veterinary Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2008
Publication Date: 3/11/2010
Publication URL: ddr.nal.usda.gov/dspace/bitstream/10113/40677/1/IND44334511.pdf
Citation: Balachandran, A., Harrington, N., Algire, J., Souyrine, A., Spraker, T., Jeffrey, M., Gonzalez, L., Orourke, K.I. 2010. Experimental oral transmission of chronic wasting disease to red deer (Cervus elaphus elaphus): Early detection and late stage distribution of protease-resistant prion protein. Canadian Veterinary Journal. Canadian Veterinary Journal. 51:169-178. 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.