Comparison of levels of HIV-1 resistance to protease inhibitors by recombinant versus conventional virus phenotypic assay and two genotypic interpretation procedures in treatment-naive and HAART-experienced HIV-infected patients.

OBJECTIVES To compare genotypic and phenotypic HIV-1 drug resistance assays. METHODS Protease inhibitor (PI) susceptibility was phenotypically analysed in HIV-1 isolates and recombinant viruses expressing proteases from viral isolates. Two genotypic interpretation methods were carried out in parallel. RESULTS Entirely concordant resistance levels were shown in 5/10 (50%) highly active anti-retroviral therapy (HAART)-experienced patients, whereas minor discrepancies were observed in the remaining five patients. CONCLUSIONS The four assays provide comparable results. The recombinant virus phenotypic assay may provide the most accurate evaluation of resistance; however, genotypic interpretation procedures are helpful for daily therapeutic decisions.