OBJECTIVE: To determine whether maternal plasma HIV viral load as measured by RT PCR for HIV RNA predicts vertical transmission. METHODS: Plasma was collected at 1st, 2nd, and 3rd trimester and delivery (visits 1,2,3 and 4, respec) from HIV-infected pregnant women enrolled to the Women and Infant Transmission Study at 6 sites in the US and Puerto Rico and stored at -7OC until thawed and analyzed in batch. HIV-1 RNA was determined using the Roche Amplicor HIV Monitor Kit (400 copies/ml dectable) after deheparinization by silica binding. All assays were run with the complete ACTG QC panel. HIV-infected offspring were classified as early if positive culture less than or equal to 7 d of age and late if neg 1st culture, then pos at greater than 7 d of age. Infants with neg cultures for greater than 6 mo were defined as uninfected. 115 maternal sample sets were analyzed (43ZDV tx). Results:(Table: See Text). In the ZDV naive qroup at delivery, 0/12 transmitted if less than 1000 copies/ml; 7/20 if 1,000-5000; 6/12 if 5,000-10,000; and 11/28 if greater than or equal to 10,0OO copies HIV RNA/ml respectively. CONCLUSIONS: ZDV naive transmitters tended to have higher RNA copy no. than non-transmitters. Mothers of infants with an early positive culture tended to have higher RNA copy no. than those of late positive infants. Lack of transmission was associated with a low/undetectable maternal RNA, but an absolute correlation with rate of transmission was not seen.

*Disease Transmission, Vertical Female HIV Infections/BLOOD/*TRANSMISSION HIV-1/GENETICS/*ISOLATION & PURIF Human Polymerase Chain Reaction Pregnancy Pregnancy Complications, Infectious ABSTRACT

www.aegis.org