title: Immunogenicity of iron-regulated outer membrane proteins of Pasteurella multocida A:3 in cattle: molecular characterization of the immunodominant heme acquisition system receptor (HasR) protein.
abstract: The iron-regulated outer membrane proteins (IROMPs) of Pasteurella multocida A:3 strain 232 (Pm232), a bovine isolate, were investigated as potential immunogens in cattle. We addressed the ability of P. multocida IROMP-enriched fractions to induce antibody responses in cattle by different vaccination strategies and the protective efficacy of these antibodies using a P. multocida-induced pneumonia challenge model. Vaccination of cattle with outer membrane-enriched fractions derived from Pm232 grown on either iron-depleted (IROMPs) or iron-sufficient (OMPs) conditions induced significant antibody responses; however, the correlation with lung lesion scores was not significant (P = 0.01 and P < 0.07, respectively). SDS-PAGE, Western blots and densitometric analyses of Pm232 grown under iron-deficient conditions revealed five major IROMPs including an immunodominant 96 kDa protein band. Mass spectrometry analysis of the 96kDa protein band suggested homology with the heme acquisition system receptor (HasR) of avian P. multocida (strain Pm70) and was confirmed by DNA sequence analysis of the cloned Pm232 hasR gene. Further analyses indicated that Pm232 HasR is a surface-exposed OMP and conserved among most P. multocida isolates investigated. In addition, cattle vaccinated with live Pm232 or IROMPs had significantly higher antibody responses to the 96 kDa protein band and the correlation with lung lesion scores approached significance (P = 0.056). These results indicate that antibody responses in cattle are induced by P. multocida IROMPs, and that the 96 kDa HasR protein is an immunodominant IROMP.
authors.affiliation: Department of Veterinary Pathobiology, College of Veterinary Medicine, Oklahoma State University, RM 250 McElroy Hall, Stillwater, OK 74078-2007, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: Prado
authors.forename: S M
authors.initials: SM
authors.lastname: Dabo
authors.forename: A W
authors.initials: AW
authors.lastname: Confer
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis* / Q000097:blood; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology; D001426:Bacterial Proteins / Q000276:immunology*; D001428:Bacterial Vaccines / Q000276:immunology; D001483:Base Sequence; D015153:Blotting, Western / Q000662:veterinary; D002417:Cattle; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel / Q000662:veterinary; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D016056:Immunodominant Epitopes / Q000235:genetics / Q000276:immunology; D007501:Iron / Q000378:metabolism; D033862:Iron-Binding Proteins; D008970:Molecular Weight; D016979:Pasteurella multocida / Q000276:immunology*; D012766:Pasteurellosis, Pneumonic / Q000276:immunology / Q000517:prevention & control*; D033902:Periplasmic Binding Proteins; D011897:Random Allocation; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics* / Q000276:immunology; D014611:Vaccination / Q000662:veterinary
chemical_list: D000907:Antibodies, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D001428:Bacterial Vaccines; D016056:Immunodominant Epitopes; D033862:Iron-Binding Proteins; D033902:Periplasmic Binding Proteins; D011956:Receptors, Cell Surface; C028027:heme receptor; D007501:Iron