Approximately 15%-40% of children born to HIV-1 seropositive mothers will be infected, and the prognosis for these infants is poor. Factors that determine whether or not a child becomes infected are currently not understood, and methods for early diagnosis of HIV infection in neonates need to be established. The major goals of this study are a) evaluation of newly developed methods for early detection of HIV-1 infection in infants, b) comparison of maternal and infant viral antigenic determinants, and c) investigation of maternal and neonatal humoral responses in relation to the occurrence of perinatal transmission of HIV-1. Methods to be studied for early detection include measurement of infant IgA anti-HIV-l antibody in sera by ELISA and Western blot assays, detection of in vitro antibody production, virus isolation from CD8+-depleted infant PBMC, and PCR detection of proviral DNA. Molecular studies will address which maternal HIV-1 quasi-species are perinatally transmitted, and compare antigenic regions from maternal and infant viruses. Maternal and infant viral env regions encoding the V3 loop will be amplified from PBMC by PCR, cloned and sequenced to obtain consensus and variant V3 sequences. These mother and infant V3 sequences will be used for synthesis of peptides in studies focused on the role of maternal antibodies to the V3 region of gpl2O. We will measure maternal and infant seroreactivity to these V3 peptides with ELISA assays designed to assess affinity/avidity. Knowledge of the V3 sequences in the mother and/or infected infant is required to accurately assess the role of V3 directed antibodies in virus transmission. There is some urgency to resolve this question. If indeed V3 reactivity serves as a marker for infant protection this would be useful for targeting infants as candidates for interventive therapeutics as well as suggesting other immune based interventive strategies. The role of specific HIV-1 neutralizing antibodies will be investigated in relation to perinatal transmission. Maternal and infant sera will be assayed for their ability to neutralize both maternal- and infant-derived viral isolates. With a better understanding of factors influencing the transmission of HIV-1 from mother to child, strategies for intervention can be developed.
