Posted by 
An infected mother can transmit HIV-1 to her child during pregnancy, while breastfeeding, or at the time of delivery. Antiretroviral drugs reduce transmission risk, immune system proteins that can attack viruses in a mother might be less effective against certain genetic variants of HIV-1 in the mother’s body, this allows transmission of resistant viruses to her infant at delivery.
The research team analyzed HIV-1 viruses present in blood samples from different infants infected at delivery and their mothers; the samples had been collected in the early 1990s in the Women and Infants Transmission Study, before antiretroviral treatments were available. The researchers sequenced the HIV-1 variants, and for each mother-infant pair, they tested the sensitivity of both transmitted and non-transmitted viruses to antibodies concurrently present in the mother’s blood.
The analysis showed that most HIV-1 variants transmitted to infants at delivery were more resistant to the mothers’ antibodies than were non-transmitted variants. However, the transmitted viruses were sensitive to a separate panel of broadly neutralizing HIV-1 antibodies, which can block infection of diverse HIV-1 strains. Genetic analysis uncovered particular sites in the membrane-proximal external region (MPER) and variable loop 3 (V3) of the HIV-1 envelope glycoprotein may be important in mediating maternal antibody resistance.
These findings could lead to development of a new vaccine for pregnant mothers with HIV-1. Such a vaccine would boost maternal antibody attack of HIV-1 variants circulating in the blood, so that transmission risk is reduced when an infant is exposed to maternal blood during delivery.
haleplushearty.org