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. MATERIALS AND 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.
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. MATERIALS AND 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: Filipa F Vale; Alexandra Nunes; Mónica Oleastro; João P Gomes; Daniel A Sampaio; Raquel Rocha; Jorge M B Vítor; Lars Engstrand; Ben Pascoe; Elvire Berthenet; Samuel K Sheppard; Matthew D Hitchings; Francis Mégraud; Jamuna Vadivelu; Philippe Lehours Journal: Sci Rep Date: 2017-02-16 Impact factor: 4.379