Peptide mimotopes of complex carbohydrates in Salmonella enterica serovar typhi which react with both carbohydrate-specific monoclonal antibody and polyclonal sera from typhoid patients

Microbiol Immunol. 2007;51(11):1045-52. doi: 10.1111/j.1348-0421.2007.tb03997.x.

Abstract

Polyclonal sera from typhoid patients and a monoclonal antibody, mAb ATVi, which recognizes the capsular polysaccharide Vi antigen (ViCPS), were used to select for peptides that mimic the ViCPS by using a phage-displayed random 12-mer peptide library. Two major common mimotopes selected from the library carried the amino acid sequences TSHHDSHGLHRV and ENHSPVNIAHKL. Enzyme-linked immunosorbent assays (ELISAs) showed that these peptides carry mimotopes to ViCPS. Phage clones that contained the 12-mer peptides were also tested against pooled/individual typhoid patients' sera and found to have 3 to 5 times higher binding compared to normal sera. By using Phage-ELISA assays, the derived synthetic peptides, TSHHDSHGLHRV and ENHSPVNIAHKL, were tested against a monoclonal antibody mAb ATVi and over 2-fold difference in binding was found between these peptides and a control unrelated peptide, CTLTTKLYC. Inhibition of the mAb's binding to ViCPS indicated that the synthetic peptides successfully competed with the capsular polysaccharide for antibody binding.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Bacterial / blood*
  • Antibodies, Monoclonal / immunology
  • Antibody Specificity
  • Antigens, Bacterial / immunology*
  • Carbohydrates / immunology*
  • Enzyme-Linked Immunosorbent Assay
  • Epitopes / immunology
  • Humans
  • Peptide Library
  • Peptides / immunology*
  • Polysaccharides, Bacterial / immunology*
  • Salmonella typhi / chemistry*
  • Salmonella typhi / isolation & purification
  • Typhoid Fever / diagnosis
  • Typhoid Fever / immunology*

Substances

  • Antibodies, Bacterial
  • Antibodies, Monoclonal
  • Antigens, Bacterial
  • Carbohydrates
  • Epitopes
  • Peptide Library
  • Peptides
  • Polysaccharides, Bacterial