title: A novel Lawsonia intracellularis autotransporter protein is a prominent antigen.
abstract: Investigation of antigenic determinants of the microaerophilic obligate intracellular bacterium Lawsonia intracellularis using a mass spectrometry approach identified a novel bacterial protein present in an extract of cell culture medium aspirated from heavily infected in vitro cell cultures. Western immunoblotting analysis of SDS-PAGE-resolved proteins using immune sera pooled from L. intracellularis-infected pigs revealed the presence of a strongly immunoreactive band of ∼ 72 kDa. Liquid chromatography-electrospray ionization-tandem mass spectrometry analysis of this component and database mining using a fully annotated L. intracellularis genome sequence and the comprehensive GenBank prokaryotic genomic database highlighted the presence of a protein that shares little sequence similarity with other prokaryotic proteins and appears to be highly species specific. Detailed bioinformatic analyses identified the protein as member of the autotransporter protein family of surface-exposed proteins, and the designation LatA (Lawsonia autotransporter protein A) is suggested. Recognition of recombinant LatA on Western blots by a panel of sera from infected and control pigs corresponded 100% with a commercial serodiagnostic that relies on in vitro culture of this fastidious organism. LatA therefore represents a potential candidate for the development of a rapid and species-specific serodiagnostic reagent.
authors.affiliation: Foodborne Pathogen Research Group, Division of Bacteriology, Moredun Research Institute, Bush Loan, Penicuik, United Kingdom. Eleanor.Watson@moredun.ac.uk
authors.forename: Eleanor
authors.initials: E
authors.lastname: Watson
authors.forename: Ewan M
authors.initials: EM
authors.lastname: Clark
authors.forename: M Pilar
authors.initials: MP
authors.lastname: Alberdi
authors.forename: Neil F
authors.initials: NF
authors.lastname: Inglis
authors.forename: Megan
authors.initials: M
authors.lastname: Porter
authors.forename: Lisa
authors.initials: L
authors.lastname: Imrie
authors.forename: Kevin
authors.initials: K
authors.lastname: McLean
authors.forename: Erin
authors.initials: E
authors.lastname: Manson
authors.forename: Alex
authors.initials: A
authors.lastname: Lainson
authors.forename: David G E
authors.initials: DG
authors.lastname: Smith
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D000942:Antigens, Bacterial / Q000032:analysis / Q000276:immunology* / Q000378:metabolism*; D015153:Blotting, Western; D019295:Computational Biology; D045824:Desulfovibrionaceae Infections / Q000175:diagnosis / Q000662:veterinary; D007118:Immunoassay; D020639:Lawsonia Bacteria / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism*; D013058:Mass Spectrometry; D026901:Membrane Transport Proteins / Q000032:analysis / Q000276:immunology* / Q000378:metabolism*; D013552:Swine
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D026901:Membrane Transport Proteins