Three genes which have variants acting as anti-HIV-1 were described so far. Among three, two are genes encoding receptors for chemokines, namely CCR5 and CCR2, which act as entry coreceptors for HIV-1 virus. The other gene is SDF1 gene. SDF-1, a cytokine belonging to the chemokine family has an inhibitory activity against the HIV-1 infection, because SDF-1 Is the physiological ligand for CXCR4, the entry coreceptor for T tropic HIV-1 virus. Recently, an SDF1 gene polymorphism was figured out to be one of the human genetic factors which regulate the period between the HIV-1 infection and the AIDS onset. By this finding, it was strongly suggested that SDF-1 regulates the onset of AIDS in the actual human population.