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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Virus and Prion Research » Research » Publications at this Location » Publication #140042
Title: TRANSMISSION OF TRANSMISSIBLE MINK ENCEPHALOPATHY (TME) TO RACCOONS (PROCYON LOTOR) BY INTRACEREBRAL INOCULATION

Author
item Hamir, Amirali
item Miller, Janice
item O'Rourke, Katherine
item BARTZ, JASON - CREIGHTON UNIVERSITY
item STACK, MICK - VLA, WEYBRIDGE, UK
item CHAPLIN, MELANIE - VLA, WEYBRIDGE, UK

Submitted to: Journal of Veterinary Diagnostic Investigation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2003
Publication Date: 1/1/2004
Citation: Hamir, A.N., Miller, J.M., O'Rourke, K.I., Bartz, J.C., Stack, M.J., Chaplin, M.J. 2004. Transmission of transmissible mink encephalopathy (TME) to raccoons (Procyon lotor) by intracerebral inoculation. Journal of Veterinary Diagnostic Investigation. 16(1):57-63.

Interpretive Summary: To determine the transmissibility of transmissible mink encephalopathy (TME) agent to raccoons and to provide information about clinical course, lesions and suitability of currently used diagnostic tests for detection of TSEs in raccoons, 4 raccoon kits were inoculated in the brain with a brain suspension from mink experimentally infected with TME. One uninoculated raccoon kit served as a control. All 4 animals in the TME-inoculated group became sick and were euthanized between 21 and 23 weeks post inoculations (PI). Necropsy examinations revealed no gross lesions. However, laboratory tests were positive for the disease (spongiform encephalopathy). These findings further confirm that TME is transmissible to raccoons and that tests currently used for transmissible spongiform encephalopathy (TSE) in livestock detects the disease (prion protein) in raccoon tissues. According to previously published data, the incubation period of sheep scrapie in raccoons is 2 years, whereas chronic wasting disease (CWD) had not shown transmission after 3 years of observation. Further studies, such as the incubation periods of bovine spongiform encephalopathy (BSE, mad cow disease) and other TSE isolates in raccoons are needed before the raccoon model can be recommended for differentiation of TSE agents. IMPACT: Since incubation periods for the 3 US TSEs (scrapie, TME and CWD) in raccoons appear to be markedly different, it may be possible to use raccoons for differentiating unknown TSE agents.

Technical Abstract: To determine the transmissibility of transmissible mink encephalopathy (TME) agent to raccoons and to provide information about clinical course, lesions and suitability of currently used diagnostic procedures for detection of TSEs in raccoons, 4 raccoon kits were inoculated intracerebrally with a brain suspension from mink experimentally infected with TME. One uninoculated raccoon kit served as a control. All 4 animals in the TME-inoculated group became sick and were euthanized between 21 and 23 weeks post inoculations (PI). Necropsy examinations revealed no gross lesions. Spongiform encephalopathy was observed by light microscopy and the presence of protease-resistant prion protein (PrPres) was detected by immunohistochemistry and Western blot techniques. Scrapie associated fibrils (SAF) were observed by negative stain electron microscopy in the brains of 3/4 inoculated raccoons. These findings further confirm that TME is transmissible to raccoons and that diagnostic techniques currently used for transmissible spongiform encephalopathy (TSE) in livestock detects prion protein in raccoon tissue. According to previously published data, the incubation period of sheep scrapie in raccoons is 2 years, whereas chronic wasting disease (CWD) had not shown transmission after 3 years of observation. Since incubation periods for the 3 US TSEs (scrapie, TME and CWD) in raccoons appear to be markedly different, it may be possible to use raccoons for differentiating unknown TSE agents. However, further studies, such as the incubation periods of bovine spongiform encephalopathy (BSE) and other TSE isolates in raccoons, as well as characterization of the raccoon PrP gene and information concerning PrP polymorphisms are needed before the model can be further characterized for differentiation of TSE agents.