QUANTITATIVE-ANALYSIS OF THE ENDOGENOUS REVERSE-TRANSCRIPTASE REACTIONS OF HIV TYPE-1 VARIANTS WITH DECREASED SUSCEPTIBILITY TO AZIDOTHYMIDINE AND NEVIRAPINE

A large number of nucleoside analog and nonnucleoside inhibitors of HI V-1 reverse transcriptase (RT) have been developed for clinical use, D ata confirm that;resistant variants of HIV-1 rapidly emerge in respons e to the selective pressure of treatment with these agents, Detection of drug resistance generally involves detection of specific mutations in the viral genome or demonstrating a failure of the drug to suppress virus replication in culture, We have developed a PCR-based method to quantitatively examine HIV-1 DNA synthesis in vitro in endogenous rev erse transcription reactions and tested it as a method to detect resis tance to RT inhibitors, Under certain conditions, we were able to dist inguish HIV strains with high-level resistance to azidothymidine triph osphate inhibition from sensitive strains, This method was quite usefu l as an assay to detect resistance to nevirapine, a nonnucleoside RT i nhibitor; in reconstruction experiments, nevirapine-resistant virus wa s detectable when it represented 10 to 25% of the total amount of viru s present in reaction mixtures, These data are examined in the light o f current models of the mechanisms of action of nucleoside and nonnucl eoside RT inhibitors, This assay may be useful for detecting the emerg ence of drug-resistant HIV-1 variants during therapy.