CD4 and AIDS: As a causative agent of AIDS, HIV, a member of the genus Lentivirus in the family Retroviridae, binds to its target CD4+ T cells through binding of the gp120 protein of the virus to the CD4 molecule, and loss of infectivity with the virus collected from HIV-infected cells with CQ treatment was reported in comparison to the virus from the untreated cells, suggesting that CQ changed the structure of HIV gp120 which bound to the host cell receptor (Savarino et al., 2001).