Regulation of HIV-1 Infection in Cells Derived from Purified CD34+ Cells Through Manipulation of APOBEC3G Expression.

The cytidine deaminase APOBEC3G has been identified as an antiviral host factor that combats HIV-1. The protein was found to be present in HIV-1 target cells such as macrophages and dendritic cells. The antiviral state of these cells has been partially attributed to a G→A hypermutation of the HIV genome caused by APOBEC3G during reverse transcription. However, the viral infectivity factor (Vif) counteracts this antiviral mechanism by inducing the inactivation of APOBEC3G. In this study, we tested the effect of APOBEC3G expression on the HIV-1 infection of cells derived from purified CD34+ cells that have been transduced with lentiviral vectors containing APOBEC3G and/or shRNAs directed against APOBEC3G and then have been differentiated before infection with HIV-1. In cell lines, the infection was strongly inhibited after upregulation of APOBEC3G. The infection could then be rescued after transducing these cells with shRNAs targeting APOBEC3G. In cells derived from purified CD34+ cells a strong inhibition of the HIV-1 infection was observed in both a Vif defective HIV-1 virus and the corresponding wild-type HIV-1 virus with Vif. Our data implies that when APOBEC3G is expressed high enough, it can escape the inhibition from Vif, thereby exerting its antiviral activity.