Vertical transmission of human immunodeficiency virus type 1: seroreactivity by maternal antibodies to the carboxy region of the gp41 envelope glycoprotein.

Maternal antibodies against the envelope glycoprotein of human immunodeficiency virus type 1 (HIV-1) have previously been suggested to be important in influencing the rate of vertical transmission. In this study, serum antibody responses in mothers who did or did not transmit HIV-1 infection to their children were measured against the carboxy region of the transmembrane envelope glycoprotein gp41. Results indicate significantly higher binding reactivity of nontransmitter mothers compared with transmitters to three peptides spanning amino acids 771-810 and 841-856. In addition, high neutralization titers in maternal sera against HIV-1(MN) were associated with a nontransmission status. This is the initial report demonstrating a correlation between maternal antibody binding to epitopes within the carboxy region of gp41 envelope glycoprotein and lack of vertical transmission. Immunodetection that identifies antibodies to these regions in gp41 could therefore be considered a strategy to assess the risk of vertical transmission of HIV-1.