|Hall, S mark|
Submitted to: Journal of Veterinary Diagnostic Investigation
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/20/2006
Publication Date: 3/1/2007
Citation: Richt, J.A., Kunkle, R.A., Alt, D., Nicholson, E.M., Hamir, A.N., Czub, S., Kluge, J., Davis, A.J., Hall, S.M. 2007. Identification and characterization of two bovine spongiform encephalopathy cases diagnosed in the United States. Journal of Veterinary Diagnostic Investigation. 19(2):142-154. Interpretive Summary: Bovine spongiform encephalopathy (BSE), also known as "mad cow disease," is a transmissible spongiform encephalopathy of cattle, first detected in 1986 in the United Kingdom and subsequently in other countries. Here we report the identification and characterization the two cases of BSE diagnosed in the United States. BSE case 1 (12/2003) and BSE case 2 (11/2004) were identified and characterized using various diagnostic methods specific for BSE (rapid test, Western blot, immunohistochemistry). Sequencing of the prion protein gene of both BSE-positive animals revealed that the sequences of both cattle were similar as previously reported for cattle. These results confirm that two cases of BSE have been identified in the United States so far: one in a cow imported from Canada and one in a cow born and raised in Texas.
Technical Abstract: Bovine spongiform encephalopathy (BSE) is a transmissible spongiform encephalopathy of cattle, first detected in 1986 in the United Kingdom and subsequently in other countries. It is the most likely cause of variant Creutzfeldt-Jakob disease (vCJD) in humans, but the origin of BSE has not been elucidated so far. Here we report the identification and characterization of the two cases of BSE diagnosed in the United States. Case 1 (12/2003) revealed spongiform changes in the obex area of the brainstem and the presence of the abnormal form of the prion protein, PrP**Sc, in the same brain area, by immunohistochemistry and Western blot analysis. Initial suspect diagnosis of BSE for case 2 (11/2004) was made by a rapid ELISA-based BSE test. Case 2 did not reveal unambiguous spongiform changes in the obex area, but PrP**Sc was detected by immunohistochemistry and enrichment Western Blot analysis in the obex. Using Western blot analysis, PrP**Sc from case 1 showed molecular features similar to typical BSE isolates, whereas PrP**Sc from case 2 revealed an unusual molecular PrP**Sc pattern: molecular mass of the unglycosylated and monoglycosylated isoform was higher than that of typical BSE isolates and case 2 was strongly labeled with antibody P4, which is consistent with a higher molecular mass. Sequencing of the prion protein gene of both BSE-positive animals revealed that the sequences of both animals were within the range of the prion protein gene sequence diversity previously reported for cattle.