title: The Presence of Phage Orthologous Genes in Helicobacter pylori Correlates with the Presence of the Virulence Factors CagA and VacA.
abstract: BACKGROUND
  The bacterium Helicobacter pylori is associated with ulcers and the development of gastric cancer. Several genes, including cytotoxin-associated gene A (CagA) and vacuolating cytotoxin A (VacA), are associated with increased gastric cancer risk. Some strains of H. pylori also contain sequences related to bacteriophage phiHP33; however, the significance of these phage-related sequences remains unknown.
  
  
  METHODS
  We assessed the extent to which phiHP33-related sequences are present in 335 H. pylori strains using homology searches then mapped shared genes between phiHP33 and H. pylori strains onto an existing phylogeny.
  
  
  RESULTS
  One hundred and twenty-one H. pylori strains contain phage orthologous sequences, and the presence of the phage-related sequences correlates with the presence of CagA and VacA. Mapping of the phage orthologs onto a phylogeny of H. pylori is consistent with the hypothesis that these genes were acquired by horizontal gene transfer.
  
  
  CONCLUSIONS
  phiHP33 phage orthologous sequences might be of significance in understanding virulence of different H. pylori strains.
authors.affiliation: Department of Biology, Georgetown University, Washington, DC, USA.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Kyrillos
authors.affiliation: Department of Biology, Georgetown University, Washington, DC, USA.
authors.forename: Gaurav
authors.initials: G
authors.lastname: Arora
authors.affiliation: Department of Biology, Georgetown University, Washington, DC, USA.
authors.forename: Bradley
authors.initials: B
authors.lastname: Murray
authors.affiliation: Department of Biology, Georgetown University, Washington, DC, USA.
authors.forename: Anne G
authors.initials: AG
authors.lastname: Rosenwald
mesh_terms: D000942:Antigens, Bacterial / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D001435:Bacteriophages / Q000235:genetics*; D016481:Helicobacter Infections / Q000382:microbiology*; D016480:Helicobacter pylori / Q000235:genetics* / Q000472:pathogenicity; D006801:Humans; D010802:Phylogeny; D013274:Stomach Neoplasms / Q000382:microbiology*; D013276:Stomach Ulcer / Q000382:microbiology*; D037521:Virulence Factors / Q000235:genetics
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C074689:VacA protein, Helicobacter pylori; D037521:Virulence Factors; C080866:cagA protein, Helicobacter pylori
keywords: CagA; VacA; horizontal gene transfer