Glycosylation of the major outer capsid protein of bluetongue viruses.

The major outer capsid protein, VP5, of five US bluetongue viruses, was found to be glycosylated. Enzymatic removal of the carbohydrate moiety did not affect the electrophoretic mobility of VP5 in SDS-PAGE, indicating the presence of only short and possibly unbranched oligosaccharide chains. The surface accessibilities and immunogenic specificities of two conformational-dependent antigenic epitopes on VP5 of BTV were not affected by deglycosylation. Selective binding of those lectins which have well-defined sugar specificities suggests that the potential short N-linked carbohydrate chain present on BTV VP5 might be composed of sialic acid alpha(2-6)-N-acetylgalactosamine-beta(1-3)-galactose-beta(1-4)-N- acetylglucosamine-beta(1-2)-mannose-N-acetylglucosamine-Asn. In accordance with the standard nomenclature, BTV-VP5 should now be termed GP5 due to the presence of the carbohydrate moiety.