Peptide mimotopes of complex carbohydrates in Salmonella enterica serovar typhi which react with both carbohydrate-specific monoclonal antibody and polyclonal sera from typhoid patients.
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.
Thong
Kwai-Lin
KL
Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia. thongkl@um.edu.my
Tang
Swee-Seong
SS
Tan
Wen-Siang
WS
Devi
Shamala
S
D000907:Antibodies, Bacterial / Q000097:blood*; D000911:Antibodies, Monoclonal / Q000276:immunology; D000918:Antibody Specificity; D000942:Antigens, Bacterial / Q000276:immunology*; D002241:Carbohydrates / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology; D006801:Humans; D019151:Peptide Library; D010455:Peptides / Q000276:immunology*; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D012485:Salmonella typhi / Q000737:chemistry* / Q000302:isolation & purification; D014435:Typhoid Fever / Q000175:diagnosis / Q000276:immunology*
D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D000942:Antigens, Bacterial; D002241:Carbohydrates; D000939:Epitopes; D019151:Peptide Library; D010455:Peptides; D011135:Polysaccharides, Bacterial