title: Identification and characterization of H-2d restricted CD4+ T cell epitopes on Lpp20  of Helicobacter pylori.
abstract: BACKGROUND
  Previous investigation has demonstrated that CD4+ T cells play a crucial role in effective immunity against Helicobacter pylori (H.pylori) infection. It has been well proved that Lpp20 is one of major protective antigens that induce immune responses after H.pylori invades host. Therefore it is valuable to identify CD4+ T cell epitopes on Lpp20, which is uncharacterized.
  
  
  METHODS
  Putative epitopes of H-2d restricted CD4+ T cell on Lpp20 of H.pylori were predicted by the SYFPEITHI algorithm and then eight hypothetical epitope peptides were synthesized. After BALB/c mice were primed with recombinant Lpp20, splenic CD4+ T cells were isolated and stimulated with synthesized peptides to measure T cell proliferation and MHC restriction. Cytokine profile was determined by ELISA and real-time PCR. Two identified epitopes were used to immunize mice to investigate CD4+ T cell response by flow cytometry.
  
  
  RESULTS
  Two of eight peptides were able to stimulate CD4+ T cell proliferation and were mapped to residues 83-97aa and 58-72aa on Lpp20 respectively. These two peptides additively stimulated Th1 cells to secrete IFN-γ. The percentage of CD4+ T cell from mice immunized with two identified epitopes respectively was higher than the control group.
  
  
  CONCLUSIONS
  The identification and characterization of two CD4+ T cell epitopes of Lpp20 helps understand the protective immunity of Lpp20 in H.pylori infection and design effective epitope vaccines against H.pylori.
authors.affiliation: Institute of Biotherapy, School of Biotechnology, Southern Medical University, North1838 Guangzhou Road, Guangzhou 510515, PR China. liyan_nys@hotmail.com
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Yin
authors.initials: Y
authors.lastname: Jiang
authors.forename: Yue
authors.initials: Y
authors.lastname: Xi
authors.forename: Lili
authors.initials: L
authors.lastname: Zhang
authors.forename: Jun
authors.initials: J
authors.lastname: Luo
authors.forename: Diandian
authors.initials: D
authors.lastname: He
authors.forename: Shuang
authors.initials: S
authors.lastname: Zeng
authors.forename: Yunshan
authors.initials: Y
authors.lastname: Ning
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000942:Antigens, Bacterial / Q000737:chemistry / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D049109:Cell Proliferation; D016207:Cytokines / Q000378:metabolism; D018984:Epitopes, T-Lymphocyte / Q000737:chemistry / Q000276:immunology*; D005260:Female; D016480:Helicobacter pylori / Q000276:immunology*; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D007114:Immunization; D008074:Lipoproteins / Q000737:chemistry / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000276:immunology; D011485:Protein Binding / Q000276:immunology; D013154:Spleen / Q000276:immunology; D018417:Th1 Cells / Q000378:metabolism
chemical_list: D000942:Antigens, Bacterial; D016207:Cytokines; D018984:Epitopes, T-Lymphocyte; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; D008074:Lipoproteins; C089630:Lpp20 protein, Helicobacter pylori; D010455:Peptides