title: Proteomic characterization of Helicobacter pylori CagA antigen recognized by child serum antibodies and its epitope mapping by peptide array.
abstract: Serum antibodies against pathogenic bacteria play immunologically protective roles, and can be utilized as diagnostic markers of infection. This study focused on Japanese child serum antibodies against Helicobacter pylori, a chronically-infected gastric bacterium which causes gastric cancer in adults. Serological diagnosis for H. pylori infection is well established for adults, but it needs to be improved for children. Serum samples from 24 children, 22 H. pylori (Hp)-positive and 2 Hp-negative children, were used to catalogue antigenic proteins of a Japanese strain CPY2052 by two-dimensional electrophoresis followed by immunoblot and LC-MS/MS analysis. In total, 24 proteins were identified as candidate antigen proteins. Among these, the major virulence factor, cytotoxin-associated gene A protein (CagA) was the most reactive antigen recognized by all the Hp-positive sera even from children under the age of 3 years. The major antigenic part of CagA was identified in the middle region, and two peptides containing CagA epitopes were identified using a newly developed peptide/protein-combined array chip method, modified from our previous protein chip method. Each of the epitopes was found to contain amino acid residue(s) unique to East Asian CagA. Epitope analysis of CagA indicated importance of the regional CagA antigens for serodiagnosis of H. pylori infection in children.
authors.affiliation: Department of Biochemistry and Functional Proteomics, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, Japan.
authors.forename: Junko
authors.initials: J
authors.lastname: Akada
authors.affiliation: Sasayama Medical Center, Hyogo College of Medicine, Sasayama, Hyogo, Japan; Department of General Medicine and Community Health Science, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan.
authors.forename: Masumi
authors.initials: M
authors.lastname: Okuda
authors.affiliation: Department of Biochemistry and Functional Proteomics, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, Japan.
authors.forename: Narumi
authors.initials: N
authors.lastname: Hiramoto
authors.affiliation: Department of Biochemistry and Functional Proteomics, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Kitagawa
authors.affiliation: Department of Biochemistry and Functional Proteomics, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, Japan.
authors.forename: Xiulian
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Technical Research Laboratory, Toyo Kohan Company, Ltd., Kudamatsu, Yamaguchi, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Kamei
authors.affiliation: Technical Research Laboratory, Toyo Kohan Company, Ltd., Kudamatsu, Yamaguchi, Japan.
authors.forename: Akane
authors.initials: A
authors.lastname: Ito
authors.affiliation: Innovation Center with University-Industry-Public Cooperation, Organization for Research Initiatives, Yamaguchi University, Tokiwadai, Ube, Yamaguchi, Japan.
authors.forename: Mikiko
authors.initials: M
authors.lastname: Nakamura
authors.affiliation: Department of Molecular Pathology, Oita University, Faculty of Medicine, Oita University, Yufu, Oita, Japan.
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Uchida
authors.affiliation: Wakayama-Rosai Hospital, Wakayama, Wakayama, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Hiwatani
authors.affiliation: Sasayama Medical Center, Hyogo College of Medicine, Sasayama, Hyogo, Japan; Department of General Medicine and Community Health Science, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Fukuda
authors.affiliation: Department of Microbiology and Immunology, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, Japan.
authors.forename: Teruko
authors.initials: T
authors.lastname: Nakazawa
authors.affiliation: Department of Biochemistry and Functional Proteomics, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kuramitsu
authors.affiliation: Department of Biochemistry and Functional Proteomics, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, Japan.
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Nakamura
mesh_terms: D000942:Antigens, Bacterial / Q000276:immunology*; D001426:Bacterial Proteins / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D018604:Epitope Mapping; D016481:Helicobacter Infections / Q000175:diagnosis* / Q000276:immunology; D016480:Helicobacter pylori / Q000276:immunology*; D006801:Humans; D040901:Proteomics
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C080866:cagA protein, Helicobacter pylori