On the antigenic determinants of the lipopolysaccharides of Vibrio cholerae O:1, serotypes Ogawa and Inaba.

This 2-O-methylated, terminal monosaccharide is the dominant serotype-specific determinant for 2 mAbs specific for the LPS from Ogawa strain, since they do not show any appreciable affinity for internal residues shared by the O-polysaccharides of both Inaba and Ogawa strains. The IgG1 monoclonal antibodies S-20-4 and A-20-6, and the IgA,kappa 2D6, all specific for the LPS from Ogawa strain, are shown to recognize preferentially the 2-O-methylated, terminal monosaccharide since that residue contributed ~90% of the maximal binding energy shown by the hexasaccharide terminal region. For 2D6, the reactivity was determined in competitive ELISA. Also, monosaccharide analogs are recognized similarly as long as they share the 2-O-methyl group. Moreover, the mAbs do not show any appreciable affinity for internal residues, shared by the O-polysaccharides of both Inaba and Ogawa strains.