title: B-cell epitope KT-12 of enterohemorrhagic Escherichia coli O157:H7: a novel peptide vaccine candidate.
abstract: Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is associated with hemorrhagic colitis, thrombotic thrombocytopenic purpura, and hemolytic-uremic syndrome in humans. B-cell epitopes of intimin γ from EHEC O157:H7 were predicted and synthesized for evaluating their immunogenicity and protective effect and for screening a novel synthetic peptide vaccine. In the present study, five B-cell epitopes of IntC300 were predicted by Hopp-Woods, Chou-Fasman, Karplus-Schulz, Emini, Jameson-Wolf and Kolaskar-Tongaonakar analysis. One of them, KT-12 (KASITEIKADKT) was coupled with keyhole limpet hemocyanin, and used to immunize BALB/c mice three times by subcutaneous and intranasal injection. Mouse serum titers of IgG and IgA were assessed by indirect ELISA. Oral inoculation of EHEC O157:H7 resulted in infection and death of the mice. It was found that B-cell epitopes are located within or near the peptide segments 658-669, 711-723, 824-833, 897-914, 919-931. Both subcutaneous and intranasal immunization induced higher concentrations of IgG antibodies, as detected by indirect ELISA, and nasal-mucosal immunization induced the production of high concentrations of IgA antibodies. After infection with a lethal dose of EHEC O157:H7, the survival rate of mice that had received subcutaneous immunization was not significantly different from that of the control group (P > 0.05). On the other hand, mice that received intranasal immunization showed a better survival rate than the group that received subcutaneous immunization (P < 0.05). The synthesized antigenic peptide KT-12 induced mice to produce higher concentrations of IgG and IgA after immunization, but only intranasal immunization of KT-12 succeeded in protecting most mice from infection with EHEC O157:H7. This study suggests that the synthesized antigenic peptide KT-12 is be a potential vaccine candidate against EHEC O157:H7.
authors.affiliation: Department of Microbiology, School of Public Health and Tropical Medicine, Southern Medical University, Tonghe, Guangzhou 510515, China.
authors.forename: Cheng-song
authors.initials: CS
authors.lastname: Wan
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhou
authors.forename: Yang
authors.initials: Y
authors.lastname: Yu
authors.forename: Li Juan
authors.initials: LJ
authors.lastname: Peng
authors.forename: Wei
authors.initials: W
authors.lastname: Zhao
authors.forename: Xue-li
authors.initials: XL
authors.lastname: Zheng
mesh_terms: D018829:Adhesins, Bacterial / Q000008:administration & dosage / Q000737:chemistry / Q000276:immunology*; D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology; D018604:Epitope Mapping; D018985:Epitopes, B-Lymphocyte / Q000008:administration & dosage / Q000737:chemistry / Q000276:immunology*; D004927:Escherichia coli Infections / Q000276:immunology* / Q000382:microbiology / Q000517:prevention & control; D019453:Escherichia coli O157 / Q000276:immunology* / Q000502:physiology; D029968:Escherichia coli Proteins / Q000008:administration & dosage / Q000737:chemistry / Q000276:immunology*; D022361:Escherichia coli Vaccines / Q000008:administration & dosage / Q000737:chemistry / Q000276:immunology*; D005260:Female; D006801:Humans; D007114:Immunization; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data
chemical_list: D018829:Adhesins, Bacterial; D000907:Antibodies, Bacterial; D018985:Epitopes, B-Lymphocyte; D029968:Escherichia coli Proteins; D022361:Escherichia coli Vaccines; C073819:eaeA protein, E coli