In HIV-1 infected cells, CUL-5, a member of the Cullin family, interacts with HIV-1 protein Vif and functions as an E3 ubiquitin ligase to induce polyubiquitination and proteasomal degradation of host antiviral protein APOBEC3G42, thereby promoting HIV-1 infection. This evidence concerns the gene CUL5 and HIV-1 infection.