Characteristics of an SA 11 rotavirus variant differing in the outer capsid glycoprotein

The ease with which variants of rotaviruses arise has been further illustrated by the isolation of a variant of simian rotavirus SA 11 differing in the major outer capsid glycoprotein VP7. The difference in mol.wt. between VP7 of the variant (STA virus) and SA 11 virus was 3 X 10(3), with this polypeptide of STA virus still retaining the mannose-rich carbohydrate moiety. Limited proteolytic analysis using Staphylococcus aureus V.8 protease and trypsin also showed a difference in structure between the VP7 of the two viruses. SA 11 and STA viruses differed antigenically, although they could not be considered to be different serotypes. In other properties, such as rate of growth, the two viruses appeared to be very similar. The evidence overall pointed to STA virus being a variant strain rather than a reassortant, but the appearance of such variants may prove to have important implications in rotavirus immunoprophylaxis.