VERTICAL TRANSMISSION OF HIV-1 - CORRELATION WITH MATERNAL VIRAL LOADAND PLASMA-LEVELS OF CD4 BINDING-SITE ANTI-GP120 ANTIBODIES

Almost all childhood HIV-1 is now acquired through vertical transmissi on. Identifying factors that affect the rate of transmission may lead to the initiation of specific preventive strategies. In this study, an tibody levels against different neutralizing epitopes on the envelope glycoprotein of HIV-1 (gp120) were measured in HIV-1-infected pregnant women that either transmitted HIV-1 to their infants (18 women) or di d not (29 women). Differences in levels of antibodies directed against the monomeric gp120 molecule and against the V3 loop region of gp120 were not significantly different between the two groups studied. Howev er, significant differences were observed in the levels of CD4 binding site antibodies, as determined by the ability of diluted maternal pla sma to inhibit binding of the CD4 binding site monoclonal antibody F10 5 (mAb F105) to monomeric gp120. In addition, more nontransmitting mot hers had low viral load as defined by having two or more negative HIV- 1 viral cultures during pregnancy compared with transmitters. This pil ot study suggests that in addition to higher viral load, low levels of CD4 binding site antibodies correlate with increased risk of HIV-1 ve rtical transmission. Passive immunotherapy with broadly neutralizing C D4 binding site antibodies should be considered as a strategy to reduc e this risk.