Inhibition by azidothymidine triphosphate of reverse transcriptase from paired AZT-susceptible and -resistant primary isolates of human immunodeficiency virus type 1

The kinetics and inhibition by 3′-azido-3′-deoxythymidine triphosphate (AZT-TP) of reverse transcriptase (RT) from paired AZT-susceptible and -resistant primary isolates of HIV-1 taken from patients before and after therapy were examined in vitro. The resistant isolates showed mutations in the RT at positions 67, 70, 215 and 219, and also in one case at positions 41 and 215. No changes in the V max , the K m for dTTP or the K i for AZT-TP of a magnitude sufficient to account for the observed development of resistance to AZT in primary isolates from these patients were found.