Identification of Core B Cell Epitope in the Synthetic Peptide Inducing Cross-Inhibiting Antibodies to a Surface Protein Antigen of Streptococcus Mutans

A surface protein antigen (PAc) of Streptococcus mutans, in particular, A—region of the molecule, has been considered as a possible target for the development of an effective anticaries vaccine. This region might be implicated in the induction of dental caries via interaction with salivary components. We have recently specified a unique peptide, TYEAALKQYEADL, as one of the minimum peptides that completely corresponds to the amino acid sequence of a part of the A—region. The unique peptide contains both T and B cell epitopes for the induction of cross—reacting antibodies to the PAc. In this study, we synthesized valine or glycine—substituted peptide analogs of this peptide and examined core B cell epitopes of this unique peptide by using ELISA inhibition assay. As a result, the core amino acid residues of—Y—Y—for B cell recognition were found to likely be not only important amino acids stabilizing the structure, but also might be essential for induction of the cross-inhibiting antibodies against PAc. These results will hopefully provide us with useful information for the design of an effective anticaries peptide vaccine.