title: HorB (HP0127) is a gastric epithelial cell adhesin.
abstract: BACKGROUND
  The Helicobacter pylori protein HorB (encoded by HP0127) is a member of a paralogous family that includes the adhesins BabA, AlpA, AlpB, and HopZ, which contribute to adhesion to gastric epithelial cells. Of the verified H. pylori porins, the HorB sequence is most similar to that of HopE, but the function of HorB is unknown. The aim of our study was to investigate the role of HorB in H. pylori gastric epithelial cell adhesion.
  
  
  METHODS
  We disrupted the horB gene in H. pylori and measured the adhesion to gastric epithelial cells (AGS cells). We then assessed the effect that HorB disruption had on lipopolysaccharide (LPS) O-chain production and Lewis x and Lewis y antigen expression. A HorB mutant in the mouse-adapted strain H. pylori SS1 was created by marker exchange and mouse stomach colonization was quantified. Using reverse transcription polymerase chain reaction, human gastric biopsy material from H. pylori-infected patients was then examined for expression of the horB gene.
  
  
  RESULTS
  Disruption of the horB gene reduced H. pylori adhesion by more than twofold. Adhesion in the horB knockout strain was restored to wild-type levels by re-introduction of HorB into the chromosome. Disruption of HorB reduced production of LPS O-chains and lowered the level of expression of Lewis x and Lewis y antigens. Insertional mutagenesis of the horB gene in H. pylori SS1 reduced mouse stomach colonization threefold. Finally, expression of the horB gene was detected in human gastric biopsy material from H. pylori-infected patients.
  
  
  CONCLUSIONS
  From these data we conclude that HorB has a role in H. pylori adhesion during infection.
authors.affiliation: Department of Microbiology and Alimentary Pharmabiotic Centre, University College Cork, Ireland. b.snelling@ulster.ac.uk
authors.forename: William J
authors.initials: WJ
authors.lastname: Snelling
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Moran
authors.forename: Kieran A
authors.initials: KA
authors.lastname: Ryan
authors.forename: Paul
authors.initials: P
authors.lastname: Scully
authors.forename: Kieran
authors.initials: K
authors.lastname: McGourty
authors.forename: Jakki C
authors.initials: JC
authors.lastname: Cooney
authors.forename: Heidi
authors.initials: H
authors.lastname: Annuk
authors.forename: Paul W
authors.initials: PW
authors.lastname: O'Toole
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics / Q000276:immunology* / Q000502:physiology; D000818:Animals; D001422:Bacterial Adhesion / Q000276:immunology*; D004847:Epithelial Cells / Q000382:microbiology*; D041981:Gastrointestinal Tract / Q000166:cytology; D015870:Gene Expression; D016481:Helicobacter Infections / Q000378:metabolism*; D016480:Helicobacter pylori / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D051379:Mice
chemical_list: D018829:Adhesins, Bacterial; C521329:HorB protein, Helicobacter pylori