Impaired immune function remains a major problem in HIV infection, primarily due to CD4+T cell decline and hypofunction, which is attributed to the lytic destruction of infected CD4+T lymphocytes by HIV and the damage caused by the targeting of uninfected CD4+T cells by the glycoprotein gp120, which is attacked by CD8+ cytotoxic T cell-mediated cytotoxicity (CTL) and antibody-dependent cytotoxicity (ADCC). Here, CD4 is linked to HIV infectious disease.