Browsing by Author "Breurec, S."
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- Dormant phages of Helicobacter pylori reveal distinct populations in EuropePublication . Vale, F.F; Vadivelu, J.R.; Oleastro, Mónica; Breurec, S.; Engstrand, L.; Perets, T.T.; Mégraud, F.; Lehours, P.Prophages of Helicobacter pylori, a bacterium known to co-evolve in the stomach of its human host, were recently identified. However, their role in the diversity of H. pylori strains is unknown. We demonstrate here and for the first time that the diversity of the prophage genes offers the ability to distinguish between European populations, and that H. pylori prophages and their host bacteria share a complex evolutionary history. By comparing the phylogenetic trees of two prophage genes (integrase and holin) and the multilocus sequence typing (MLST)-based data obtained for seven housekeeping genes, we observed that the majority of the strains belong to the same phylogeographic group in both trees. Furthermore, we found that the Bayesian analysis of the population structure of the prophage genes identified two H. pylori European populations, hpNEurope and hpSWEurope, while the MLST sequences identified one European population, hpEurope. The population structure analysis of H. pylori prophages was even more discriminative than the traditional MLST-based method for the European population. Prophages are new players to be considered not only to show the diversity of H. pylori strains but also to more sharply define human populations.
- Screening of Prophage Sequences Among Helicobacter PyloriPublication . Timóteo, Andreia; Breurec, S.; Oleastro, Mónica; Roxo-Rosa, Mónica; Vítor, Jorge; Lehours, Phillipe; Vale, FilipaUntil recently, Helicobacter pylori was considered a bacterium without prophages. The presence of an incomplete prophage sequence in strain B38 and a complete prophage sequence in strain B45 showed otherwise. Using a PCR strategy, based on degenerated primers designed after aligning bacteriophage integrase genes from H. pylori strains B38 and B45, and H. acinonychis prophage II, we found that integrase sequence was present in 21.4% (73/341) of the H. pylori clinical strains tested. The phylogenetic analysis of the sequenced region revealed that strains cluster according to their geographic origin, but not to their pathology. We have applied the same methodology to additional 147 European strains and 77 African strains, determining the presence of integrase sequence in 25.2% (37/147) of the former and in 19.5% (15/77) of the latter. Currently, we have a total of 565 strains screened for the presence of integrase gene, with 125 positive for this sequence (22.1%). To understand if these integrase sequences belong to reminiscent or complete prophages we are also screening for the presence of other prophage coding sequences. Among integrase positive strains, we found 19.2% (5/26) positive strains for the primase sequence and 53.3% (8/15) for the presence of the end of the phage. Presently, we are running the sequencing of the PCR amplified products in order to conduct the phylogenetic analysis. The results reinforce the abundance of prophages sequences in H. pylori and suggest that the majority of them belong to reminiscent prophages integrated within the bacterium genome.