Infectivity assay of wt HIV strains and the PNGS mutants. a) Comparison of the infectivity of wt HIV-1 strains: FE and four other strains. b) Infectivity assay result of all FE PNGS mutants. c) Comparison of relative infectivity of some of the PNGS mutants in FE, Sc19-15 and YU-2 isolates. Data are shown as relative luminescence units (RLU) in a logarithmic scale. Relative infectivity was calculated by dividing the Log10 (RLU of mutant) by Log10 (RLU of wt). The data represent the means of three independent experiments, and the error bars indicate the standard deviations from the means. The cut off value of the infectivity assay is 4.0. #, glycan deletion mutant that could not support virus entry.