Applicability for High-throughput screening (HTS). Drug-sensitivity of wild-type (Pol wt) and mutant gag-pol (Pol NRFQ = D67N/K70R/T215F/K219Q) proteins was tested using HTS (A) as compared to conventional FACS screening (B). As exemplarily shown for AZT, very similar results were obtained with both methods. GFP expressing wild-type strain (filled squares/dark blue) and mCherry-expressing quadruple mutant strain (filled diamonds/light blue) are shown. HTS analysis was based on 2,400 cells whereas 10,000 cells were analysed by FACS. Note that both vectors were pseudotyped with ecotropic envelope protein compatible with S1 biosafety environment. P-values that were significantly different between the second data group are denoted with *, for values < 0.05 or **, for values < 0.0001.