Peptide Mimotopes of Complex Carbohydrates in Salmonella enterica serovar typhi which React with both carbohydrate-Specific Monoclonal Antibody and Polyclonal Sera from Typhoid Patients

• Main Authors: Thong, Kwai Lin, Tang, Swee Seong, Tan, Wen Siang, Devi, Shamala
• Format: Article
• Published: Wiley 2007
• Subjects: Q Science (General); QH Natural history; QR Microbiology
• Online Access: http://eprints.um.edu.my/5601/; https://doi.org/10.1111/j.1348-0421.2007.tb03997.x

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.