Submitted to: Veterinary Pathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/12/2005
Publication Date: 3/1/2006
Citation: Hamir, A.N., Kunkle, R.A., Miller, J.M., Bartz, J.C., Richt, J.A. 2006. First and second cattle passage of transmissible mink encephalopathy (TME) by intracerebral inoculation. Veterinary Pathology. 43(2):118-126. Interpretive Summary: Transmissible mink encephalopathy (TME) is a fatal neurologic disease. It is similar to bovine spongiform encephalopathy (BSE) or mad cow disease. To compare TME infection with other similar diseases in cattle, 2 groups of calves were inoculated in the brain with TME agents from 2 different sources. Two uninoculated calves served as controls. Within 15.3 months post inoculation, animals from both inoculated groups developed clinical signs of central nervous system (CNS) abnormality. Laboratory tests revealed lesions and presence of the TME agent in their tissues. Both findings could not be differentiated from those seen in BSE. Our findings also demonstrated that the laboratory tests that are currently used for BSE surveillance would detect TME in cattle should it occur naturally. However, it would be a diagnostic challenge to differentiate TME in cattle from BSE by clinical signs or laboratory tests that are currently available. Results of this study will have an impact on directing future research on TSEs to search for specific laboratory tests to differentiate BSE from TME in cattle.
Technical Abstract: To compare clinicopathological findings of transmissible mink encephalopathy (TME) with other transmissible spongiform encephalopathies (TSE, prion diseases) that have been shown to be experimentally transmissible to cattle (sheep scrapie, and chronic wasting disease, CWD), 2 groups of calves (n = 4 each) were intracerebrally inoculated with TME agents from 2 different sources (mink with TME and a bovine with TME). Two uninoculated calves served as controls. Within 15.3 months post inoculation (PI), animals from both inoculated groups developed clinical signs of central nervous system (CNS) abnormality; their CNS tissues had microscopic spongiform encephalopathy (SE); and PrPres was detected in their CNS tissues by immunohistochemistry (IHC) and Western blot (WB) techniques. These findings demonstrate that intracerebrally inoculated cattle not only amplify TME PrPres but also develop clinical CNS signs and extensive lesions of SE. The latter has not been shown with other TSE agents (scrapie and CWD) similarly inoculated into cattle. The findings also demonstrate that the diagnostic techniques currently used for bovine spongiform encephalopathy (BSE) surveillance would detect TME in cattle should it occur naturally. However, it would be a diagnostic challenge to differentiate TME in cattle from BSE by clinical signs, neuropathology, or the presence of PrPres by IHC and WB.