SIMULTANEOUS MUTATIONS AT TYR-181 AND TYR-188 IN HIV-1 REVERSE-TRANSCRIPTASE PREVENTS INHIBITION OF RNA-DEPENDENT DNA-POLYMERASE-ACTIVITY BY THE BISHETEROARYLPIPERAZINE (BHAP) U-90152S

The replacement of either Tyr-181 or Tyr-188 of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) by the corresponding HIV-2 RT amino acids Ile-181 or Leu-188 is known to result in active m utant enzymes (Y181I; Y188L) with virtual loss of sensitivity towards three structural classes of nonnucleoside RT inhibitors; L-697,661, ne virapine, and TIBO R82913, The bisheteroarylpiperazine (BHAP) U-90152S , a highly specific inhibitor (IC50, 0.29 +/- 0.01 mu M) of HIV-1 RT, inhibited the recombinant Y181I and Y188L HIV-I RT mutants,vith IC50 v alues of 3.6 +/- 0.15 mu M and 0.71 +/- 0.02 mu M, respectively, Const ruction and in vitro analysis of double mutants Y181I/Y188L and Y181C/ Y188L of HIV-1 RT showed > 150-fold resistance to U-90152S, An HIV-2 R T mutant containing amino acids 176-190 from HIV-1 RT acquired full se nsitivity to U-90152S IC50, 0.26 +/- 0.01 mu M) It is concluded that s imultaneous mutations at Tyr-181 and Tyr-188 of HIV-1 RT promotes resi stance to U-90152S.