title: Fine-mapping of immunodominant linear B-cell epitopes of the Staphylococcus aureus SEB antigen using short overlapping peptides.
abstract: Staphylococcal enterotoxin B (SEB) is one of the most potent Staphylococcus aureus exotoxins (SEs). Due to its conserved sequence and stable structure, SEB might be a good candidate antigen for MRSA vaccines. Although cellular immune responses to SEB are well-characterized, much less is known regarding SEB-specific humoral immune responses, particularly regarding detailed epitope mapping. In this study, we utilized a recombinant nontoxic mutant of SEB (rSEB) and an AlPO4 adjuvant to immunize BALB/c mice and confirmed that rSEB can induce a high antibody level and effective immune protection against MRSA infection. Next, the antisera of immunized mice were collected, and linear B cell epitopes within SEB were finely mapped using a series of overlapping synthetic peptides. Three immunodominant B cell epitopes of SEB were screened by ELISA, including a novel epitope, SEB205-222, and two known epitopes, SEB97-114 and SEB247-261. Using truncated peptides, an ELISA was performed with peptide-KLH antisera, and the core sequence of the three immunodominant B cell epitopes were verified as SEB97-112, SEB207-222, and SEB247-257. In vitro, all of the immunodominant epitope-specific antisera (anti-SEB97-112, anti-SEB207-222 and anti-SEB247-257) were observed to inhibit SEB-induced T cell mitogenesis and cytokine production from splenic lymphocytes of BALB/c mice. The homology analysis indicated that SEB97-112 and SEB207-222 were well-conserved among different Staphylococcus aureus strains. The 3D crystal structure of SEB indicated that SEB97-112 was in the loop region inside SEB, whereas SEB207-222 and SEB247-257 were in the β-slice region outside SEB. In summary, the fine-mapping of linear B-cell epitopes of the SEB antigen in this study will be useful to understand anti-SEB immunity against MRSA infection further and will be helpful to optimize MRSA vaccine designs that are based on the SEB antigen.
authors.affiliation: National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, PR China.
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Zhao
authors.affiliation: National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, PR China.
authors.forename: Bin
authors.initials: B
authors.lastname: Li
authors.affiliation: National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, PR China.
authors.forename: He-Qiang
authors.initials: HQ
authors.lastname: Sun
authors.affiliation: National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, PR China.
authors.forename: Jin-Yong
authors.initials: JY
authors.lastname: Zhang
authors.affiliation: National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, PR China.
authors.forename: Yi-Lin
authors.initials: YL
authors.lastname: Wang
authors.affiliation: National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, PR China.
authors.forename: Li
authors.initials: L
authors.lastname: Chen
authors.affiliation: Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, PR China.
authors.forename: Jian
authors.initials: J
authors.lastname: Hu
authors.affiliation: Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, PR China.
authors.forename: Ya-Fei
authors.initials: YF
authors.lastname: He
authors.affiliation: National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, PR China.
authors.forename: Hao
authors.initials: H
authors.lastname: Zeng
authors.affiliation: National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, PR China.
authors.forename: Quan-Ming
authors.initials: QM
authors.lastname: Zou
authors.affiliation: National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, PR China.
authors.forename: Chao
authors.initials: C
authors.lastname: Wu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001428:Bacterial Vaccines / Q000737:chemistry / Q000276:immunology; D049109:Cell Proliferation; D016207:Cytokines / Q000378:metabolism; D004768:Enterotoxins / Q000737:chemistry / Q000276:immunology*; D018604:Epitope Mapping; D018985:Epitopes, B-Lymphocyte / Q000737:chemistry / Q000276:immunology*; D005260:Female; D006801:Humans; D016056:Immunodominant Epitopes / Q000737:chemistry / Q000276:immunology*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000276:immunology*; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000276:immunology; D013203:Staphylococcal Infections / Q000276:immunology / Q000517:prevention & control*; D013601:T-Lymphocytes / Q000502:physiology; D014611:Vaccination
chemical_list: D001428:Bacterial Vaccines; D016207:Cytokines; D004768:Enterotoxins; D018985:Epitopes, B-Lymphocyte; D016056:Immunodominant Epitopes; D010446:Peptide Fragments; C031818:enterotoxin B, staphylococcal