Correlation of maternal cytophilic human immunodeficiency virus (HIV)-1 V3 loop peptide-specific antibodies in infants with vertical HIV transmission.

Approximately 70% of human immunodeficiency virus (HIV)-1-infected pregnant women do not transmit HIV to their offsprings. The identification of factors involved in maternal-child transmission of HIV is important for the design and implementation of therapeutic and prevention strategies. Recently we have developed a modified peripheral mononuclear cell (PBMC) culture system for in vitro antibody production (IVAP) by which we can distinguish serum-derived cytophilic anti-HIV-1 antibody from de novo synthesized antibody. In this study, we analyzed the presence of antibodies directed to HIV-1 gp160, gp120, gp41, and V3 loop synthetic peptides (C51, C53, and C57 from MN and IIIB strains) utilizing the grid-blot method in PBMC cultures of 52 mother-child pairs. Among the mothers (39 nontransmitters and 13 transmitters), presence of serum-derived cytophilic antibodies or de novo synthesized HIV V3 loop peptide-specific antibodies did not correlate with vertical transmission. However, PBMC-associated, cytophilic antibodies of maternal origin reactive with C51, C53, and C57 from MN and IIIB strains were identified in cultures of uninfected infants, but not in infected infants. These observations suggest that cytophilic antibodies of maternal origin directed to HIV-1 V3 loop peptides which are bound to infant cells might play a role in preventing vertical transmission.