NEUTRALIZING ANTIBODY AND PERINATAL TRANSMISSION OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1

The major immunologic determinants for perinatal transmission of human immunodeficiency virus type 1 (HIV-1) remain largely unknown, The pre sence of maternal neutralizing antibodies has been proposed as an expl anation for why the majority of infants born to untreated HIV-1-infect ed women do not become infected, Using maternal and infant specimens c ollected as part of a longitudinal cohort study of perinatal transmiss ion in New York City between 1991 and 1995, we successfully obtained p rimary viral isolates from 10 of 20 perinatally nontransmitting (NTR) women, 14 of 20 perinatally transmitting (TR) women, and 13 of 13 of t heir HIV-1-infected infants, Neutralizing antibody titers were then de termined using a titer reduction assay, TR and NTR women did not diffe r in their ability to neutralize autologous virus or laboratory strain s LAI and MN, Infant viruses were not less sensitive to neutralization by maternal sera than autologous viruses, Similarly, TR and NTR isola tes were neutralized equally well using a reference serum with broad n eutralizing ability, Finally, a heteroduplex tracking assay (HTA) was used to analyze the degree of viral homology within 13 TR maternal-inf ant pairs. In eight pairs, maternal and infant isolates were highly ho mologous, In five pairs, lesser degrees of homology were observed, con sistent with perinatal transmission of a minor species, However, these isolates were no more or less resistant to maternal sera than were ho mologous isolates, Thus we found no association between the presence o f neutralizing antibody in maternal sera as measured by a titer reduct ion neutralization (inactivation) assay and perinatal transmission of HIV-1.