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Lack of a maternal viral threshold for vertical transmission of HIV-1.
Koup RA; Yunzhen C; Ho DD; Krogstad PA; Chen IS; Korber BT; Wolinsky SM;
November 30, 1996
3rd Conf Retro and Opportun Infect. 1996 Jan 28-Feb 1;:161. Unique

As part of the Ariel Project, we prospectively studied 151 HIV-1-infected women during and after pregnancy to determine the influence of maternal virus load on vertical transmission. Of the 151 infected pregnant women, 19 gave birth to infants infected with HIV-1 as determined by repeated positive culture and PCR results. Maternal viral load in plasma (RT-PCR, Roche) and PBMC (quantitative cultures and proviral DNA PCR) was determined during the first, second and third trimesters of pregnancy, at delivery, and 2 and 6 months after delivery. Mean viral loads were higher in the transmitting than the non-transmitting mothers (eg. plasma load at delivery of 5245 copies/ml vs. 2633 copies/ml, respectively), but there was large overlap in the data sets and the differences were not statistically significant. In addition, there was no evidence for a plasma viral load threshold above which there was a high likelihood of transmission. Transmission rates were below 25% even for mothers with plasma viral loads in the upper quartile of all patients in the study. The predictive value of a woman with a single plasma virus load greater than 50,000 copies/ml at any time point during pregnancy of transmitting was 40%, while the predictive value of not having a plasma load greater than 50,000 copies/ml for non-transmission was 89% as compared to the non-transmission rate of 86% in the absence of any test. Maternal viral load is a poor predictor of mother-to-infant transmission of HIV-l.

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