NEUTRALIZING ANTIBODY IMMUNE-RESPONSE IN CHILDREN WITH PRIMARY AND SECONDARY ROTAVIRUS INFECTIONS

We have characterized the neutralizing antibody immune response to six human rotavirus serotypes (G1 to G4, G8, and G9) in Brazilian childre n with primary and secondary rotavirus infections and correlated the r esponse with the G serotype of the infecting rotavirus strain. Twenty- five children were studied: 17 had a single rotavirus infection, 4 wer e reinfected once, and 4 experienced three infections. Two of the rein fections were by non-group A rotaviruses. Among the 25 primary infecti ons, we observed homotypic as well as heterotypic responses; the serot ype G1 viruses, which accounted for 13 of these infections, induced mo stly a homotypic response, while infections by serotype G2 and G4 viru ses induced, in addition to the homotypic, a heterotypic response dire cted primarily to serotype G1. Two of the primary infections induced h eterotypic antibodies to 69M, a serotype G8 virus that by RNA electrop horesis analysis was found not to circulate in the population during t he time of the study. The specificity of the neutralizing antibody imm une response induced by a virus of a given serotype was the same in pr imary 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 sero type.