DECAY OF TRANSPLACENTAL HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 ANTIBODIES IN NEONATES AND INFANTS

Transplacental human immunodeficiency virus (HIV) antibodies from 11 u ninfected and 3 infected infants of HIV-seropositive mothers were meas ured using end point titration of twofold dilutions of sera by a parti cle-agglutination method. Four or more sequential serum samples from e ach infant were collected between birth and age greater than or equal to 14 months and analyzed. Linear regression of log(2) antibody titers of uninfected infants plotted against age (days) showed an exponentia l decay in maternal HIV antibodies. The mean half-life of passive HIV antibodies was 23.1 +/- SD 4.2 days (range, 18.2-29.3; 95% confidence interval, 20.2-26.0). The median age of clearance of maternal HIV anti bodies was 13.3 months (range, 10.4-15.6). A model assuming first-orde r exponential decay and production of HIV antibodies was fitted to the time course of antibody titers of the infected infants. Minimal titer s in each infected infant occurred at 5.5, 4.9, and 4.0 months, and do ubling times of HIV antibodies from that point ranged from 16.8 to 31. 4 days.