Evidence for efficient vertical transfer of maternal HIV-1 envelope-specific neutralizing antibodies but no association of such antibodies with reduced infant infection.

: Little is known about the efficiency of vertical transfer of HIV-1-specific antibodies. Antibody levels in plasma from 60 mother-infant pairs near the time of birth, including 14 breast-feeding transmission pairs, were compared. The envelope-binding titers were strongly correlated (r = 0.91, P < 0.0001) and similar (1.4-fold greater in maternal plasma) between a mother and her corresponding infant as were the neutralizing antibody (Nab) levels (r = 0.80, P < 0.0001; 1.3-fold higher), suggesting efficient transfer. There was no significant difference in Nab responses between transmitting and nontransmitting mothers, although there was a trend for transmitting mothers to have higher HIV-1-specific Nabs.