Determination of linear B-cell epitopes and immunogenic peptide mapping of wild-type ADI. Spots 1 to 133 are 15-residue-long peptides encompassing the ADI sequence immobilized on cellulose membrane. Each peptide is shifted by 3 amino acids toward the C terminus. (A to G) Membranes probed with pooled serum from BALB/c mice (n = 5) subcutaneously immunized as follows: A, wild-type ADI; B, TBS (sham); C, D166A mutant ADI; D, E220A mutant ADI; E, H275A mutant ADI; F, D277A mutant ADI; G, C401A mutant ADI. (H) Linear B-cell epitopes are highlighted in rainbow colors, starting with blue at the N terminus and ending with red at the C terminus. Individual residues targeted by site-directed mutagenesis are in bold with underlining. (I) Immunogenic epitopes in the structure of GAS ADI are highlighted in rainbow colors.