title: The fimbrial protein FlfA from Gallibacterium anatis is a virulence factor and vaccine candidate.
abstract: The Gram-negative bacterium Gallibacterium anatis is a major cause of salpingitis and peritonitis in egg-laying chickens, leading to decreased egg production worldwide. Widespread multidrug resistance largely prevents treatment of this organism using traditional antimicrobial agents, while antigenic diversity hampers disease prevention by classical vaccines. Thus, insight into its pathogenesis and knowledge about important virulence factors is urgently required. A key event during the colonization and invasion of mucosal surfaces is adherence, and recently, at least three F17-like fimbrial gene clusters were identified in the genomes of several G. anatis strains. The objective of this study was to characterize the putative F17-like fimbrial subunit protein FlfA from G. anatis 12656-12 and determine its importance for virulence. In vitro expression and surface exposure of FlfA was demonstrated by flow cytometry and immunofluorescence microscopy. The predicted function of FlfA as a fimbrial subunit protein was confirmed by immunogold electron microscopy. An flfA deletion mutant (ΔflfA) was generated in G. anatis 12656-12, and importantly, this mutant was significantly attenuated in the natural chicken host. Furthermore, protection against G. anatis 12656-12 could be induced by immunizing chickens with recombinant FlfA. Finally, in vitro expression of FlfA homologs was observed in a genetically diverse set of G. anatis strains, suggesting the potential of FlfA as a serotype-independent vaccine candidate This is the first study describing a fimbrial subunit protein of G. anatis with a clear potential as a vaccine antigen.
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health Sciences, University of Copenhagen, Frederiksberg C, Denmark.
authors.forename: Ragnhild J
authors.initials: RJ
authors.lastname: Bager
authors.forename: Barbara
authors.initials: B
authors.lastname: Nesta
authors.forename: Susanne E
authors.initials: SE
authors.lastname: Pors
authors.forename: Marco
authors.initials: M
authors.lastname: Soriani
authors.forename: Laura
authors.initials: L
authors.lastname: Serino
authors.forename: John D
authors.initials: JD
authors.lastname: Boyce
authors.forename: Ben
authors.initials: B
authors.lastname: Adler
authors.forename: Anders M
authors.initials: AM
authors.lastname: Bojesen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001428:Bacterial Vaccines / Q000276:immunology*; D002645:Chickens; D003001:Cloning, Molecular; D010861:Fimbriae, Bacterial; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D015661:Pasteurellaceae / Q000235:genetics / Q000378:metabolism*; D016871:Pasteurellaceae Infections / Q000517:prevention & control / Q000662:veterinary; D011201:Poultry Diseases / Q000382:microbiology / Q000517:prevention & control; D016415:Sequence Alignment; D037521:Virulence Factors / Q000235:genetics / Q000276:immunology / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D001428:Bacterial Vaccines; D037521:Virulence Factors