|Hall, S Mark|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 1/2/2004
Publication Date: 1/4/2004
Citation: Richt, J.A., Kluge, J.P., Alt, D.P., Kunkle, R.A., Hamir, A.N., Czub, S., Davis, A.J., Hall, S. 2004. Identification and characterization of the first U.S. bovine spongiform encephalopathy case. Poster created for use by the USDA at a meeting with the Office of International Epizootics. Interpretive Summary:
Technical Abstract: Bovine spongiform encephalopathy (BSE) is a transmissible spongiform encephalopathy of cattle, first detected in 1986 in the U.K. and subsequently in other countries. BSE may have arisen either from the infectious agent scrapie, which causes a similar disease in sheep and goats, or from a germline mutation in the protein-coding region of the prion protein (PrP) gene of affected cattle. Here, we report on the prion protein polypeptide profile and genotype from the first identified case of BSE in the State of Washington in the United States. The six-year old Holstein cow was nonambulatory at slaughter and the formalin-fixed obex area of the brainstem was found to contain spongiform changes and vacuolated neurons by histopathology and the abnormal form of the prion protein, PrPBSE, by immunohistochemistry. Species determination was made on the formalin-fixed tissue. Extensive PrPBSE deposition in the obex was confirmed by Western blot analyses and enzyme-linked immunosorbent assay using brainstem and cerebellum derived from fresh tissue from the suspect animal. The PrPBSE polypeptide profile from the U.S. BSE case was characterized by (i) a lower molecular mass of the unglycosylated PrPBSE polypeptide fragment compared to samples from sheep with scrapie and deer with chronic wasting disease, (ii) good immunoreactivity with monoclonal antibody 6H4 directed against the central region of the PrP, but a lack of staining with monoclonal antibody P4, which recognizes the protease-resistant N-terminal end of the PrP; and (iii) a glycoform profile with a high proportion of the diglycosylated PrPBSE isoform. Comparison of the U.S. BSE isolate to the recent Canadian and European BSE isolates revealed similar sized PrPBSE polypeptide fragments using anti-PrP antibody 6H4. The PrP gene from the U.S. BSE case was amplified from both, fresh and formalin-fixed brain material and found to be of bovine origin with a normal, rather unremarkable cattle PrP sequence. This cow had a synonymous polymorphism at codon 192, and both alleles contained the six-copy octapeptide repeat region. We conclude from these studies that (i) the PrPBSE profile from the first U.S. BSE case showed similar molecular properties to the typical PrPBSE pattern described for the Canadian and European BSE isolates, and (ii) a germline mutation in the bovine PrP gene is not likely the etiological cause in this case. This information is consistent with the hypothesis that the U.S. BSE case - similar to the one in Canada - was most likely exposed to contaminated feed.