TM-Pst1 inhibition of 2G12-gp120 interaction. (A) The percent 2G12 binding to 100 ng of immobilized JR-FL gp120 was analyzed by ELISA in the presence of TM-Pst1, Pst1-Endo H, Yu2 gp120, and JR-FL gp120. There was no preincubation of inhibitors with 2G12, and 100% represents 2G12 binding in the absence of inhibitor. The values are the averages ± standard errors of the means (error bars) of three independent experiments. Molar IC50s were calculated by nonlinear regression using GraphPad Prism 5.0, using the apparent molecular masses of TM-Pst1, Yu2, and JR-FL gp120 at 100 kDa (Fig. 5B). (B) (Top) Neutralization activity of MAb 2G12 against HxB-pseudotyped virus in the presence of Pst1-Endo H and TM-Pst1, with MAb 2F5 as a control. The results are representative of three separate experiments. (Bottom) Neutralization activity of 2G12 assessed against SF162-pseudotyped virus in the presence of Pst1-Endo H and TM-Pst1. The results are representative of two separate experiments.