Evolution of HIV-1 envelope sequences and coreceptor tropism during pregnancy

Background HIV-1 Env mediates viral entry into target cells and defines R5 or X4 phenotype. HIV tropism is important in pathogenesis and is associated with mother-to-child transmission. Env is under strong selective pressure within the host. The aim of this study was to determine whether changes in maternal immunity associated with initiation and progression of pregnancy influence Env sequence variation and HIV-1 coreceptor usage.