We have characterized the
neutralizing antibody immune response to six human rotavirus serotypes (G1 to G4, G8, and G9) in Brazilian children with primary and secondary
rotavirus infections and correlated the response with the G serotype of the infecting rotavirus strain. Twenty-five children were studied: 17 had a single
rotavirus infection, 4 were reinfected once, and 4 experienced three
infections. Two of the
reinfections were by non-group A rotaviruses. Among the 25 primary
infections, we observed homotypic as well as heterotypic responses; the serotype G1 viruses, which accounted for 13 of these
infections, induced mostly a homotypic response, while
infections by serotype G2 and G4 viruses induced, in addition to the homotypic, a heterotypic response directed primarily to serotype G1. Two of the primary
infections induced
heterotypic antibodies to 69M, a serotype G8 virus that by
RNA electrophoresis analysis was found not to circulate in the population during the time of the study. The specificity of the
neutralizing antibody immune response induced by a virus of a given serotype was the same in primary as well as
secondary infections. These results indicate that the heterotypic immune response induced in a primary
rotavirus infection is an intrinsic property of the virus strain, and although there seem to be general patterns of serotype-specific seroconversion, these may vary from serotype to serotype and from strain to strain within a serotype.