Determination of mAb epitopes by surface mutant libraries and ELISA. mAbs 2D10, 2H2, 3D10, and 2C6 were tested for binding against a panel of Sal-1 DBP surface mutants as described in Experimental Procedures. (A) Sal-1 DBP wild type. (B) Mutant 6 (K414A, P430A, P431A, N434A, K437A, Q441A). (C) Mutant 9 (N434R, K437R). (D) Mutant 1 (N218S, R221G, K222S, R223G). (E) Mutant 12 (K479A, Q480A). (F) Mutant 8 (K428A, P430A). All error bars are ±1 SD, calculated from three replicate experiments.