Rotavirus subgroups and serotypes in Pune, India

Group A rotavirus-positive stool specimens, collected from 432 hospitalized patients of all age groups with diarrhoea during 1990-1997 from Pune, India, were characterized for subgroups (SGs) and G serotypes (1, 2, 3, 4, 6, 8, and 10). ELISA for subgrouping was carried out by employing subgroup I and II-specific monoclonal antibodies (MAbs). For serotyping, MAbs against G1 (Ku), G2 (S2), G3 (Yo), and G4 (ST-3) were used. In addition, MAbs against G3 (RV-3), G8 (B37), G6 (bovine U.K.), and G10 (B223) were also employed. Of the 432 specimens, 174 (40.27%) belonged to subgroup I, 187 (43.29%) to subgroup II, 15 (3.47%) to subgroup I and II, and 56 (12.96%) did not react to MAbs specific to subgroup I and subgroup II MAbs. Of the 432 specimens, 111 (25.69%) reacted to one of the MAbs used. Thirty-five of the 111 specimens were serotyped as G1, 34 as G2, and 42 as G3, G4, G6, G8, and G10. Sixty-seven (21%) specimens gave dual reaction mainly to MAbs against G6, G10; G2, and G4, and in several other combinations. Forty-seven specimens (10.88%) showed multireactivities. A large number of specimens (47.92%) did not show any reactivity with MAbs employed in this study, and remained non-serotypeable. Subgroup I was found to be more common in Pune, and most specimens negative for subgroup I and II were non-serotypeable. The results implicate the need for characterization of unusual and non-typeable strains before undertaking any rotaviral vaccine studies in India.