Glycosylation patterns of the envelope glycoproteins of an equine-virulent venezuelan encephalitis virus and its vaccine derivative.

The equine-virulent Venezuelan encephalitis virus, Trinidad donkey (TRD), was compared to its vaccine derivative, TC-83 virus, by examining the glycosylation of the two structural envelope glycoproteins (E1 and E2). The number of size classes of glycopeptides on the glycoproteins was determined by P-6 column chromatography following Pronase digestion. The E1 glycoprotein had three glycopeptide size species and the E2 glycoprotein contained four size species ranging in mol. wt. from 1900 to 2700. Both viruses contained similar glycopeptide size species, although the relative amounts on the E2 glycoproteins appeared to be somewhat different. All of the glycopeptide species appeared to be complex, since all were labelled with glucosamine, mannose, galactose and fucose. No mannose-rich species could be detected. The different glycopeptide species appeared to be sialylation isomers of a smaller core glycopeptide with an apparent mol. wt. of 1800 which was the sole product following desialylation of the larger glycopeptides. The number of oligosaccharide attachment sites present on both E1 and E2 of each virus was determined using reverse-phase high pressure liquid chromatography. This analysis indicated that the E1 glycoprotein of both viruses had six or seven similar sugar-labelled peptide fragments following trypsin digestion. However, the E2 glycoprotein of TRD virus contained three oligosaccharide attachment sites, whereas TC-83 E2 glycoprotein had only two.