Fig. 4.

CD4 and HLA-I down-regulation ability of Nefs encoding escape and co-varying mutations. The CD4 down-regulation ability of the subtype B NL4-3 Nef (panel a) and the subtype C SK68 Nef (panel b) encoding the S88G mutation as well as S88G accompanied by the co-varying E98D mutation is shown. Similarly the HLA-I down-regulation ability of these mutants is shown in panels c and d. Down-regulation activity is expressed relative to the respective wild-type protein (NL4-3 or SK68), which represents 100 %. The CD4 and HLA-I down-regulation ability expressed relative to SF2 was 97 and 99 % respectively for NL4-3, and 89 and 69 % respectively for SK68. Bars represent the mean of at least 3 replicates, and error bars represent standard deviations from the means. Asterisks indicate mutant clones that were > 10 % different in function from the wild-type and were significantly different from the wild-type as indicated by the Student’s T test (p < 0.05)