RESISTANCE TO NUCLEOSIDE ANALOGS OF SELECTIVE MUTANTS OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-2 REVERSE-TRANSCRIPTASE

We have studied selected mutants of human immunodeficiency virus type 2 (HIV-2) reverse transcriptase (RT) in a cell-free system in order to assess whether the mutant proteins exhibit a reduction in the sensitivity to nucleoside analog inhibitors similar to that of HIV-1 RT. We have modified, by site-directed mutagenesis, several of those amino acid residues so that their equivalent substitutions in HIV-1 RT have led to the formation of HIV-1 RT variants with the highest degree of resistance to dideoxynucleoside triphosphates (i.e., Glu-89-->Gly, Leu-74-->Val, and Ser-215-->Tyr [which is comparable to the Thr-215-->Tyr mutation of HIV-1 RT] and the double mutations Glu-89-->Gly/Ser-215-->Tyr and Leu-74-->Val/Ser-215-->Tyr). The similarity found between resistance of the newly generated HIV-2 RT mutants to nucleoside analogs and that of the comparable mutants of HIV-1 RT can support the notion that the overall protein folding around the DNA polymerase active site in HIV-2 RT is quite similar to that of HIV-1 RT.