Development of peptide mimics of a protective epitope of Vibrio cholerae Ogawa O-antigen and investigation of the structural basis of peptide mimicry.

This epitope is a structural peptide mimic of the Ogawa O-antigen from Vibrio cholera O1. Phage display libraries were biopanned against mAbs S-20-4 and S-20-6, which are specific for the protective epitope of Ogawa LPS, using low pH elution or non-elution. This unique sequence bound both monoclonal antibodies. Alanine scanning and site-directed mutagenesis showed that residues His at position 2, Pro at position 5, Pro at position 6, Leu at position 9 and Leu at position 10 are all critical for binding these mAbs.