CD4 and infection: In vitro the transmission of HIV-1 from DCs to CD4+ T cells occurs via two mechanisms: 1) trans-infection, i.e. cell-cell transmission by capture and transfer of HIV-1 from iDCs or mDCs to CD4+ T cells which can occur within a few hours post infection with or without virus internalization (4–9); and 2) cis-infection, i.e. cell-free transmission where nascent virions from infected iDCs bud and infect CD4+ T cells which can occur within a few days and is sensitive to antiviral therapy (ART) (8–12).