title: Proteomic analysis of Lawsonia intracellularis reveals expression of outer membrane proteins during infection.
abstract: Lawsonia intracellularis is the aetiological agent of the commercially significant porcine disease, proliferative enteropathy. Current understanding of host-pathogen interaction is limited due to the fastidious microaerophilic obligate intracellular nature of the bacterium. In the present study, expression of bacterial proteins during infection was investigated using a mass spectrometry approach. LC-ESI-MS/MS analysis of two isolates of L. intracellularis from heavily-infected epithelial cell cultures and database mining using fully annotated L. intracellularis genome sequences identified 19 proteins. According to the Clusters of Orthologous Groups (COG) functional classification, proteins were identified with roles in cell metabolism, protein synthesis and oxidative stress protection; seven proteins with putative or unknown function were also identified. Detailed bioinformatic analyses of five uncharacterised proteins, which were expressed by both isolates, identified domains and motifs common to other outer membrane-associated proteins with important roles in pathogenesis including adherence and invasion. Analysis of recombinant proteins on Western blots using immune sera from L. intracellularis-infected pigs identified two proteins, LI0841 and LI0902 as antigenic. The detection of five outer membrane proteins expressed during infection, including two antigenic proteins, demonstrates the potential of this approach to interrogate L. intracellularis host-pathogen interactions and identify novel targets which may be exploited in disease control.
authors.affiliation: Moredun Research Institute, Bush Loan, Penicuik, United Kingdom. Electronic address: Eleanor.Watson@moredun.ac.uk.
authors.forename: Eleanor
authors.initials: E
authors.lastname: Watson
authors.affiliation: Moredun Research Institute, Bush Loan, Penicuik, United Kingdom; Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom.
authors.forename: M Pilar
authors.initials: MP
authors.lastname: Alberdi
authors.affiliation: Moredun Research Institute, Bush Loan, Penicuik, United Kingdom.
authors.forename: Neil F
authors.initials: NF
authors.lastname: Inglis
authors.affiliation: Moredun Research Institute, Bush Loan, Penicuik, United Kingdom.
authors.forename: Alex
authors.initials: A
authors.lastname: Lainson
authors.affiliation: Division of Infection and Immunity, The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, United Kingdom.
authors.forename: Megan E
authors.initials: ME
authors.lastname: Porter
authors.affiliation: Moredun Research Institute, Bush Loan, Penicuik, United Kingdom.
authors.forename: Erin
authors.initials: E
authors.lastname: Manson
authors.affiliation: Moredun Research Institute, Bush Loan, Penicuik, United Kingdom.
authors.forename: Lisa
authors.initials: L
authors.lastname: Imrie
authors.affiliation: Moredun Research Institute, Bush Loan, Penicuik, United Kingdom.
authors.forename: Kevin
authors.initials: K
authors.lastname: Mclean
authors.affiliation: Moredun Research Institute, Bush Loan, Penicuik, United Kingdom; Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom. Electronic address: David.G.E.Smith@moredun.ac.uk.
authors.forename: David G E
authors.initials: DGE
authors.lastname: Smith
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D019295:Computational Biology; D045824:Desulfovibrionaceae Infections / Q000276:immunology / Q000378:metabolism / Q000662:veterinary* / Q000821:virology; D016680:Genome, Bacterial / Q000235:genetics*; D054884:Host-Pathogen Interactions; D007410:Intestinal Diseases / Q000382:microbiology / Q000662:veterinary*; D020639:Lawsonia Bacteria / Q000276:immunology / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D040901:Proteomics; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology*; D053719:Tandem Mass Spectrometry
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins
keywords: Lawsonia intracellularis; Proliferative enteropathy; Serology; Shotgun proteomics; Surface proteins