FIG 4.

Phe43 cavity and inner domain changes enhance susceptibility of the CRF01_AE HIV-1 strain to ADCC responses mediated by HIV⁺ sera in the presence of CD4mc. (A to C) Cell surface staining of primary CD4⁺ T cells infected with a CRF01_AE transmitted-founder (TF) strain (40061) and variants with 10 different HIV⁺ sera. (A) Histograms depicting representative HIV⁺ serum staining. (B and C) The graphs shown represent the compiled mean fluorescence intensities (MFI) obtained with 10 HIV⁺ sera (B) and the fold increase in MFI in the presence of CD4mc calculated for the infected (p24⁺) population (C). (D and E) Infected primary CD4⁺ T cells were also used as target cells, and autologous PBMCs were used as effector cells in a FACS-based ADCC assay. The graphs shown represent (D) the ADCC values and (E) the increase (in percentage points) of ADCC levels obtained in the presence of CD4mc with 10 HIV⁺ sera. These results were obtained in at least 2 independent experiments. Error bars indicate means ± SEM. Statistical significance was tested using a paired t test or a Wilcoxon rank test based on statistical normality (**, P < 0.01; ***, P < 0.001; ****, P < 0.0001; ns, nonsignificant).