SEROTYPE SPECIFICITY OF THE NEUTRALIZING-ANTIBODY RESPONSE INDUCED BYTHE INDIVIDUAL SURFACE-PROTEINS OF ROTAVIRUS IN NATURAL INFECTIONS OFYOUNG-CHILDREN

The relative contribution of the rotavirus surface proteins, VP4 and V P7, to the induction of homotypic as weal as heterotypic neutralizing antibodies (NtAbs) in natural infections,vas studied. The NtAb titers of paired sera from 70 infants with serologically defined primary rota virus infections were determined with a panel of rotavirus reassortant s having one surface protein from a human rotavirus (serotypes G1 to G 4 for VP7 and P1A and P1B for VP4) and the other surface protein from a heterologous animal rotavirus strain. A subset of 37 children were e valuated for epitope-specific antibodies to the two proteins by an epi tope-blocking assay. The infants mere found to seroconvert more freque ntly to VP4 than to VP7 by both methods, although the titers of the se roconverters were higher to VP7 than to VP4, Both proteins induced hom otypic as well as heterotypic NtAbs. G1 VP7 frequently induced a respo nse to both G1 and G3 VP7s, while G3 VP7 and P1A VP4 induced mostly ho motypic responses.