THE MUTATION FREQUENCY OF FELINE IMMUNODEFICIENCY VIRUS ENHANCED BY 3'-AZIDO-3'-DEOXYTHYMIDINE

We have developed a host range system to measure the mutation frequenc y of feline immunodeficiency virus (FIV), the feline homologue of huma n immunodeficiency virus type 1 (HIV-I). When wild-type FIV was grown in the presence of a known mutagen, 5-bromo-2'-deoxquridine (BUdR), a dose-dependent increase of host range mutants was detected. Using this system, we have evaluated the effects of antiviral drugs upon the mut ation frequency of FIV. Subinhibitory concentrations of 3'-azido-3'-de oxythymidine (AZT), the most common antiviral drug used in AIDS chemot herapy, increased the mutation frequency of FIV in a dose-dependent ma nner. Two other antivirals, 2',3'-dideoxyinosine (ddI) and 2',3'-dideo xycytidine (ddC), did not show this effect.