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.