Homotypic and heterotypic serum isotype-specific antibody responses to rotavirus nonstructural protein 4 and viral protein (VP) 4, VP6, and VP7 in infants who received selected live oral rotavirus vaccines.

Homotypic and heterotypic serum isotype-specific antibody responses to rotavirus enterotoxin nonstructural protein (NSP)-4, independent neutralization antigens viral protein (VP)-4 and VP7, and group A rotavirus common antigen VP6 were analyzed by an immunocytochemistry assay in infants who received 1 of several live oral rotavirus vaccines. Significant serum immunoglobulin (Ig) A and IgG antibody responses to homotypic and/or heterotypic NSP4s of genotype [ A], [ B], or [ C] were detected after vaccination. The magnitude of antibody responses to homotypic and heterotypic NSP4s was not significantly different, irrespective of the NSP4 genotype of the administered vaccine strain. In addition, there were no significant differences between IgA antibody responses to homotypic and heterotypic VP7s. In contrast, IgA antibody responses to VP4 were predominantly homotypic. IgA antibody responses to VP7 were lower in magnitude than those to VP4 but were comparable to those to NSP4. Antibody titers to homotypic and/or heterotypic NSP4s were positively correlated with those to VP6 before and after vaccination.