CD4 and HIV-1 infection: The initial identification of DC-SIGN as an HIV receptor permitting trans-infection of T cells led to the “Trojan horse” hypothesis, which relates the preliminary establishment of HIV-1 infection to the ability of iDCs to capture the virus via DC-SIGN in the peripheral tissue and then migrate to the lymph nodes, where HIV-1 transferred to CD4+ T cells could easily start the spread of infection [5],[7],[10].