title: Nonbinding site-directed mutants of transferrin binding protein B exhibit enhanced immunogenicity and protective capabilities.
abstract: Host-adapted Gram-negative bacterial pathogens from the Pasteurellaceae, Neisseriaceae, and Moraxellaceae families normally reside in the upper respiratory or genitourinary tracts of their hosts and rely on utilizing iron from host transferrin (Tf) for growth and survival. The surface receptor proteins that mediate this critical iron acquisition pathway have been proposed as ideal vaccine targets due to the critical role that they play in survival and disease pathogenesis in vivo. In particular, the surface lipoprotein component of the receptor, Tf binding protein B (TbpB), had received considerable attention as a potential antigen for vaccines in humans and food production animals but this has not translated into the series of successful vaccine products originally envisioned. Preliminary immunization experiments suggesting that host Tf could interfere with development of the immune response prompted us to directly address this question with site-directed mutant proteins defective in binding Tf. Site-directed mutants with dramatically reduced binding of porcine transferrin and nearly identical structure to the native proteins were prepared. A mutant Haemophilus parasuis TbpB was shown to induce an enhanced B-cell and T-cell response in pigs relative to native TbpB and provide superior protection from infection than the native TbpB or a commercial vaccine product. The results indicate that binding of host transferrin modulates the development of the immune response against TbpBs and that strategies designed to reduce or eliminate binding can be used to generate superior antigens for vaccines.
authors.affiliation: Laboratory of Immunology, Faculty of Agronomy and Veterinary Medicine, University of Passo Fundo, São José, Passo Fundo, Brazil Department of Animal Health, University of León, León, Spain.
authors.forename: Rafael
authors.initials: R
authors.lastname: Frandoloso
authors.affiliation: Department of Animal Health, University of León, León, Spain.
authors.forename: Sonia
authors.initials: S
authors.lastname: Martínez-Martínez
authors.affiliation: Department of Biochemistry, University of Toronto, Toronto, Canada.
authors.forename: Charles
authors.initials: C
authors.lastname: Calmettes
authors.affiliation: Department of Microbiology, Immunology, and Infectious Diseases, University of Calgary, Calgary, Canada.
authors.forename: Jamie
authors.initials: J
authors.lastname: Fegan
authors.affiliation: Department of Microbiology, Immunology, and Infectious Diseases, University of Calgary, Calgary, Canada.
authors.forename: Estela
authors.initials: E
authors.lastname: Costa
authors.affiliation: Department of Microbiology, Immunology, and Infectious Diseases, University of Calgary, Calgary, Canada.
authors.forename: Dave
authors.initials: D
authors.lastname: Curran
authors.affiliation: Department of Microbiology, Immunology, and Infectious Diseases, University of Calgary, Calgary, Canada.
authors.forename: Rong-Hua
authors.initials: RH
authors.lastname: Yu
authors.affiliation: Department of Animal Health, University of León, León, Spain.
authors.forename: César B
authors.initials: CB
authors.lastname: Gutiérrez-Martín
authors.affiliation: Department of Animal Health, University of León, León, Spain.
authors.forename: Elías F
authors.initials: EF
authors.lastname: Rodríguez-Ferri
authors.affiliation: Department of Biochemistry, University of Toronto, Toronto, Canada.
authors.forename: Trevor F
authors.initials: TF
authors.lastname: Moraes
authors.affiliation: Department of Microbiology, Immunology, and Infectious Diseases, University of Calgary, Calgary, Canada schryver@ucalgary.ca.
authors.forename: Anthony B
authors.initials: AB
authors.lastname: Schryvers
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis*; D001402:B-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D015870:Gene Expression; D006192:Haemophilus Infections / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control*; D018073:Haemophilus Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D044137:Haemophilus parasuis / Q000737:chemistry / Q000187:drug effects / Q000276:immunology*; D007111:Immunity, Cellular; D056724:Immunity, Humoral; D007075:Immunoglobulin M / Q000096:biosynthesis*; D007501:Iron / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D013552:Swine; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D014168:Transferrin / Q000235:genetics / Q000378:metabolism; D033882:Transferrin-Binding Protein B / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D014611:Vaccination
chemical_list: D000907:Antibodies, Bacterial; D018073:Haemophilus Vaccines; D007075:Immunoglobulin M; D011994:Recombinant Proteins; D014168:Transferrin; D033882:Transferrin-Binding Protein B; D007501:Iron