Viral infectivity factor

Viral infectivity factor, or Vif, is an accessory protein found in HIV and other lentiviruses. Its role is to disrupt the antiviral activity of the human enzyme APOBEC (specifically APOBEC3G, "A3G" in short, and other A3 enzymes) by targeting it for ubiquitination and cellular degradation. APOBEC is a cytidine deaminase enzyme that mutates viral nucleic acids.

Despite the functional and (weak) structural similarities, Vif found in lentiviruses can function in quite different ways. For example, the HIV-1 Vif ("Vif₁" hereafter) and HIV-2 Vif ("Vif₂") attach to APOBEC from different ends of themselves and have a different spectrum of inhibition. As HIV-1 is older and more virulent, many more studies have been done on the Vif₁ than on the Vif₂. Similarly, more studies have been done on the HIV/SIV Vif than on any other lentiviral Vif.