FIG 3.

Relative levels of resistance to broadly neutralizing MAbs in HIV-1 cell-to-cell transmission. Single-round cell-free and cell-to-cell neutralization assays were performed using NLCI constructs with T/F Env clones QH0692 and RHPA, laboratory-adapted NL4-3 Env, and chronic R5-tropic JR-FL Env. Error bars represent mean values and standard errors of the means (SEM) of results from duplicates of at least two independent experiments conducted on different dates. Antibodies targeting different sites of vulnerability on HIV-1 Env were tested. (A) CD4 blocking antibody Leu3a. (B) MAb targeting glycan epitope 2G12. (C) MAb targeting CD4bs VRC01 and HJ16. (D) MAb targeting membrane-proximal external region 2F5 and 4E10. (E) MAb targeting gp120/gp41 interface 35O22. (F) MAb targeting glycan-dependent V1/V2 epitope PG9. (G) MAb targeting V3 glycans PGT121, PGT126, and 10-1074. Each antibody was studied for its neutralization activity against cell-free infection and cell-to-cell infection. Cell-free neutralization curves are shown with closed circles and solid lines, and cell-to-cell neutralization curves are shown with open triangles and dotted lines.