The expression of functional recombinant envelopes on transfected HeLa cells. Env-expressing plasmids constructed from three patients carrying an amino acid N, T or I at position 140 with (V38A) without substitutions at position 38 of gp41 were transfected into HeLa cells. The surface expression of Env was analyzed 24 hours post-transfection by staining the cells with the 2G12 antibody. Env expression was determined by the percentage of Env-positive cells in an inter-patient analysis using the clones constructed from each patient or in an intra-patient analysis using clones constructed from baseline and after treatment (V38A) samples (A). The total level of Env expression was determined by calculating the relative fluorescence intensity (RFI = % of Env-positive cells × geometric mean fluorescence of Env-positive cells) in an intra-patient analysis (B). Baseline samples (white boxes) and V38A samples (gray boxes). The boxes represent the median and interquartile range of the values. The median values were compared using a nonparametric Mann Whitney test. * p < 0.05, *** p = 0.0006, and ns denotes non-significant differences.