title: Epitope-specific immune recognition of the nontypeable Haemophilus influenzae outer membrane protein 26.
abstract: Previous studies using rodent respiratory infection models of nontypeable Haemophilus influenzae (NTHi) infection have established the 26-kDa outer membrane protein of the bacterium, OMP26, as a potential vaccine antigen for NTHi. This study undertook a comprehensive immunological identification of OMP26 T- and B-cell epitopes. A series of OMP26 peptides were constructed and regions of the OMP26 antigen involved in recognition by lymphocyte receptors and induction of acquired immune responses were identified. The dominant T-cell epitopes for OMP26 were located toward the C-terminus between amino acid residues 95 and 197 (T3+T4 region) as mapped using antigen-specific lymphocyte proliferation assays. The newly identified T-cell epitopes exhibited strong capacity for efficient T-cell activation, suggesting that, compared with other OMP26 regions; epitopes within the T3+T4 region have the highest affinity for binding to major histocompatibility complex molecules. In contrast, the predominant B-cell epitopes of OMP26 were located more centrally within the molecule between amino acid residues 45 and 145 (T2+T3 region) as determined using enzyme-linked immunosorbent assay and surface plasmon resonance assays. The T2+T3 region was immunodominant in several species including chinchilla, mice and rats when assessed using both mucosal and parenteral immunization regimes. In addition, the antibodies directed against the T2+T3 region bound to intact NTHi cell surface, according to flow cytometry. Collectively, these results specifically locate the amino acid sequences containing the OMP26 T- and B-cell epitopes, which, as newly mapped antigenic epitopes for lymphocyte recognition, will be useful to improve existing NTHi vaccine strategies. Comprehensive definition of the minimum epitope length required for optimal B- and T-cell responses requires further study.
authors.affiliation: Faculty of Medical Science; Naresuan University; Phitsanulok, Thailand.
authors.forename: Duangkamol
authors.initials: D
authors.lastname: Kunthalert
authors.forename: Laura A
authors.initials: LA
authors.lastname: Novotny
authors.forename: Helen M
authors.initials: HM
authors.lastname: Massa
authors.forename: Glen C
authors.initials: GC
authors.lastname: Ulett
authors.forename: Lauren O
authors.initials: LO
authors.lastname: Bakaletz
authors.forename: Jennelle M
authors.initials: JM
authors.lastname: Kyd
authors.forename: Allan W
authors.initials: AW
authors.lastname: Cripps
mesh_terms: D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology*; D049109:Cell Proliferation / Q000187:drug effects; D002682:Chinchilla; D004797:Enzyme-Linked Immunosorbent Assay; D018604:Epitope Mapping; D018985:Epitopes, B-Lymphocyte / Q000276:immunology*; D018984:Epitopes, T-Lymphocyte / Q000276:immunology*; D006193:Haemophilus influenzae / Q000276:immunology*; D016056:Immunodominant Epitopes / Q000276:immunology; D008297:Male; D008807:Mice, Inbred BALB C; D051381:Rats; D020349:Surface Plasmon Resonance; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D001425:Bacterial Outer Membrane Proteins; D018985:Epitopes, B-Lymphocyte; D018984:Epitopes, T-Lymphocyte; D016056:Immunodominant Epitopes; C118414:OMP26 protein, Haemophilus influenzae
keywords: B and T-cell epitopes; OMP26; immune response; mucosal; nontypeable Haemophilus influenzae; outer membrane protein; parenteral; peptide vaccine; vaccine