VERTICAL TRANSMISSION OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 - AUTOLOGOUS NEUTRALIZING ANTIBODY, VIRUS LOAD, AND VIRUS PHENOTYPE

Objective: To evaluate immunologic and virologic correlates of vertical transmission of human immunodeficiency virus type 1 (HIV-1). Design: Case-control study. Patients: Women who were prospectively enrolled in a natural history study of HIV-1 infection in women and infants. Sixteen HIV-1-infected women whose infants became infected were matched by CD4(+) cell percentage and use of zidovudine during pregnancy with women whose infants did not become infected. Measurements: Maternal autologous neutralizing antibody, virus load determined by RNA-polymerase chain reaction (RNA-PCR), and virus phenotype. Results: Most women in both groups had low titers of autologous neutralizing antibody, and no difference in neutralizing titers was observed (range, <4 to 181 in both groups), The HIV-1 copy number in maternal plasma was not significantly different in the two groups but was inversely correlated with maternal CD4(+) cell percentage (p <0.005). Five women in the transmitting group and four in the nontransmitting group had syncytium-inducing (SI) phenotype virus. Two infected infants had SI phenotype virus. The SI phenotype virus was associated with a greater HIV-1 copy number in maternal plasma (p <0.05) and an increase in the mortality rate for the infants (p <0.01). Conclusions: In women matched for CD4(+) cell percentage, low titers of autologous neutralizing antibody, high virus load, and SI phenotype virus were not associated with an increased risk of transmission of HIV-1 to their infants.