Binding to soluble and cell surface trimeric gp160Δc. (A) Graphs show optical density at 405 nm (OD_405nm) for the selected IgG antibodies as measured by capture ELISA with purified BaL gp140 WT and BaL gp140_{D474A/M475A/R476A}. See also Fig. S4. Error bars represent the SD from at least two independent experiments. (B) Graphs show apparent K_A (K_A^app, M²¹) for the selected IgG antibodies as measured by surface plasmon resonance (SPR) on chips derivatized with BaL gp140 WT and BaL_{D474A/M475AR/476A}. See also Fig. S5 and Table S2. Error bars represent the SEM from at least two independent experiments. * indicates that no binding to BaL gp140_{D474A/M475A/R476A} was detected. (C) (left) Histogram plots show the binding of the selected antibodies to BaL gp160Δc and BaL gp160Δc_{D474A/M475A/R476A} expressed on GFP-positive BOSC.23 cells. Controls include mgo53 (Wardemann et al., 2003), mAbs 2–1092 (anti-VL) and b12 (anti-CD4bs). BOSC.23 cells gated on GFP^high expression. The number of binding events as percentage of the maximum was plotted against APC fluorescence intensity. (right) Graphs show apparent differences in the relative median fluorescence intensity (ΔrMFI) for the selected IgG antibodies between BaL gp160Δc and BaL gp160Δc_{D474A/M475A/R476A}. Error bars represent the SD from at least two independent experiments.