title: Comparative immunogenicity of M. hyopneumoniae NrdF encoded in different expression systems delivered orally via attenuated S. typhimurium aroA in mice.
abstract: The Mycoplasma hyopneumoniae ribonucleotide reductase R2 subunit (NrdF) gene fragment was cloned into eukaryotic and prokaryotic expression vectors and its immunogenicity evaluated in mice immunized orally with attenuated Salmonella typhimurium aroA CS332 harboring either of the recombinant expression plasmids. We found that NrdF is highly conserved among M. hyopneumoniae strains. The immunogenicity of NrdF was examined by analyzing antibody responses in sera and lung washes, and the cell-mediated immune (CMI) response was assessed by determining the INF-gamma level produced by splenocytes upon in vitro stimulation with NrdF antigen. S. typhimurium expressing NrdF encoded by the prokaryotic expression plasmid (pTrcNrdF) failed to elicit an NrdF-specific serum or secretory antibody response, and IFN-gamma was not produced. Similarly, S. typhimurium carrying the eukaryotic recombinant plasmid encoding NrdF (pcNrdF) did not induce a serum or secretory antibody response, but did elicit significant NrdF-specific IFN-gamma production, indicating induction of a CMI response. However, analysis of immune responses against the live vector S. typhimurium aroA CS332 showed a serum IgG response but no mucosal IgA response in spite of its efficient invasiveness in vitro. In the present study we show that the DNA vaccine encoding the M. hyopneumoniae antigen delivered orally via a live attenuated S. typhimurium aroA can induce a cell-mediated immune response. We also indicate that different live bacterial vaccine carriers may have an influence on the type of the immune response induced.
authors.affiliation: Department of Biological and Physical Sciences, University of Southern Queensland, Cnr Baker and West Street, Toowoomba, Qld 4350, Australia.
authors.forename: Austen Y
authors.initials: AY
authors.lastname: Chen
authors.forename: Scott R
authors.initials: SR
authors.lastname: Fry
authors.forename: Judy
authors.initials: J
authors.lastname: Forbes-Faulkner
authors.forename: Grant E
authors.initials: GE
authors.lastname: Daggard
authors.forename: T K S
authors.initials: TK
authors.lastname: Mukkur
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis; D001426:Bacterial Proteins / Q000276:immunology*; D005260:Female; D005822:Genetic Vectors; D007114:Immunization / Q000662:veterinary*; D007071:Immunoglobulin A, Secretory / Q000096:biosynthesis; D007371:Interferon-gamma / Q000096:biosynthesis; D051379:Mice; D008807:Mice, Inbred BALB C; D045705:Mycoplasma hyopneumoniae / Q000276:immunology* / Q000472:pathogenicity; D010957:Plasmids; D045729:Pneumonia of Swine, Mycoplasmal / Q000517:prevention & control*; D011994:Recombinant Proteins; D012264:Ribonucleotide Reductases / Q000276:immunology*; D022562:Salmonella Vaccines / Q000276:immunology*; D012486:Salmonella typhimurium; D013552:Swine; D014436:Typhoid-Paratyphoid Vaccines / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D007071:Immunoglobulin A, Secretory; D011994:Recombinant Proteins; D022562:Salmonella Vaccines; D014436:Typhoid-Paratyphoid Vaccines; C087350:aroA Salmonella vaccine; D007371:Interferon-gamma; C114872:NrdF protein, bacteria; D012264:Ribonucleotide Reductases; C108427:ribonucleotide reductase R2 subunit