Maternal markers affecting the risk of vertical transmission of HIV

Various seroepidemiological studies have detected a 22-39% risk of maternal-child transmission of the human immunodeficiency virus (HIV), and identification of the factors that promote in utero transmission is a critical preventive measure. Preliminary studies have confirmed a significant association between lack of vertical transmission and reactivity to certain V3 loop sequences of the HIV genome. Since the V3 loop region is the major neutralizing domain of the envelope glucoprotein gp120 and its structural integrity appears essential for viral infectivity, it has been speculated that a maternal antibody response to this region plays a role in the prevention of maternal-fetal transmission of HIV. Recent studies have shown that a least 3 sequences within the V3 loop are very conserved among more than 240 HIV isolates. These are the cysteine-containing flanking regions and the top sequence identifying the principal neutralizing domain.