title: An investigation of the expression and adhesin function of H7 flagella in the interaction of Escherichia coli O157 : H7 with bovine intestinal epithelium.
abstract: Enterohaemorrhagic Escherichia coli O157 : H7 is a bacterial pathogen that can cause haemorrhagic colitis and haemolytic uremic syndrome. In the primary reservoir host, cattle, the terminal rectum is the principal site of E. coli O157 colonization. In this study, bovine terminal rectal primary epithelial cells were used to examine the role of H7 flagella in epithelial adherence. Binding of a fliC(H7) mutant O157 strain to rectal epithelium was significantly reduced as was binding of the flagellated wild-type strain following incubation with H7-specific antibodies. Complementation of fliC(H7) mutant O157 strain with fliC(H7) restored the adherence to wild-type levels; however, complementation with fliC(H6) did not restore it. High-resolution ultrastructural and imunofluorescence studies demonstrated the presence of abundant flagella forming physical contact points with the rectal epithelium. Binding to terminal rectal epithelium was specific to H7 by comparison with other flagellin types tested. In-cell Western assays confirmed temporal expression of flagella during O157 interaction with epithelium, early expression was suppressed during the later stages of microcolony and attaching and effacing lesion formation. H7 flagella are expressed in vivo by individual bacteria in contact with rectal mucosa. Our data demonstrate that the H7 flagellum acts as an adhesin to bovine intestinal epithelium and its involvement in this crucial initiating step for colonization indicates that H7 flagella could be an important target in intervention strategies.
authors.affiliation: Division of Infection and Immunity, The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Penicuik EH25 9EZ, UK.
authors.forename: Arvind
authors.initials: A
authors.lastname: Mahajan
authors.forename: Carol G
authors.initials: CG
authors.lastname: Currie
authors.forename: Shona
authors.initials: S
authors.lastname: Mackie
authors.forename: Jai
authors.initials: J
authors.lastname: Tree
authors.forename: Sean
authors.initials: S
authors.lastname: McAteer
authors.forename: Iain
authors.initials: I
authors.lastname: McKendrick
authors.forename: Tom N
authors.initials: TN
authors.lastname: McNeilly
authors.forename: Andrew
authors.initials: A
authors.lastname: Roe
authors.forename: Roberto M
authors.initials: RM
authors.lastname: La Ragione
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Woodward
authors.forename: David L
authors.initials: DL
authors.lastname: Gally
authors.forename: David G E
authors.initials: DG
authors.lastname: Smith
mesh_terms: D018829:Adhesins, Bacterial / Q000378:metabolism*; D000818:Animals; D001422:Bacterial Adhesion; D002417:Cattle; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000382:microbiology*; D019453:Escherichia coli O157 / Q000502:physiology* / Q000648:ultrastructure; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D005407:Flagella / Q000502:physiology* / Q000648:ultrastructure; D005408:Flagellin; D020869:Gene Expression Profiling; D005816:Genetic Complementation Test; D007413:Intestinal Mucosa / Q000382:microbiology*; D009154:Mutation
chemical_list: D018829:Adhesins, Bacterial; D029968:Escherichia coli Proteins; C516095:FliC protein, E coli; D005408:Flagellin