CD4 and HIV-1 infection: CCR5 is reported to be the predominant co-receptor for mucosal HIV-1 infection in humans and is expressed on T cells, dendritic cells and macrophages in the mucosal tissue of the FGT74,93, while CCR5+ CD4+ cells are the primary HIV-1 targets for infection94–97, consistent with results from another ex vivo cervico-vaginal tissue model showing predominant R5-tropic infection98.