Identification of diverse HIV type 1 subtypes and dual HIV type 1 infection in pregnant Ugandan women

Vertical (mother-to-child) transmission accounts for the majority of pediat ric HIV-1 infections. Many factors are involved in vertical transmission, h owever it is not clear which factors are most important for determining whe ther a mother will transmit HIV-1 to her infant. It has been suggested that HIV-1 subtype may influence vertical transmission and that subtype D virus es may be less likely to be transmitted in this setting. We analyzed HIV-1 gp120 V3 region sequences from the plasma of 20 pregnant Ugandan women of k nown transmission status who did not receive antiretroviral prophylaxis. V3 regions were cloned, sequenced, and subtyped by phylogenetic analysis. Amo ng 11 women who transmitted HIV-1 to their infants, we detected subtypes A, C, D, and G, Two of the transmitters had dual infection with subtypes A an d D, In addition, a third was infected with two distinct strains of subtype G viruses. HIV-1 subtype A and D viruses were found in 9 women who did not transmit the virus to their infants. This study reveals that pregnant Ugan dan women harbor diverse HIV-1 subtypes, including women who transmit HIV-1 to their infants. Transmission of HIV-1 with subtype D V3 regions was conf irmed in 4 of the 11 transmitters, including 2 who had dual infection with subtype A and D HIV-1.