Genetic Markers of Genome Rearrangements in Helicobacter pylori.
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ABSTRACT:
SUBMITTER: Noureen M
PROVIDER: S-EPMC8002640 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Helicobacter pylori is a common bacterial infection. It can lead to severe stomach problems, including stomach cancer. Researchers want to look at samples of the bacteria. These H. pylori strains will be taken from chronically infected people. They want to identify the genetic and epigenetic differences in H. pylori strains. This could help predict which people who get infected with the bacteria will get stomach cancer. This could lead to the cancer being detected earlier. It could also mean less people get stomach cancer.
Objectives:
To study genetic variations of H. pylori strains based on samples from chronically infected people. To identify the features of strains that might lead to severe stomach problems or stomach cancer.
Eligibility:
People ages 30-70 years who need an upper endoscopy or who were recently diagnosed with stomach cancer
Design:
Participants will be screened by the doctor who does their procedure and a study nurse.
Participants who have endoscopy will have ~6 biopsies removed. These are tissue samples. They are about the size of a grain of rice. Participants will allow the study team to access reports from their stomach exam.
Participants with stomach cancer will donate some of the tissue that will be removed during their clinical care. They will allow the study team to access reports of their surgery. They will also allow them to access the microscope slides of their stomach.
| 2216372 | ecrin-mdr-crc
Project description:Helicobacter pylori colonizes the stomach of half of the world's population, causing a wide spectrum of disease ranging from asymptomatic gastritis to ulcers to gastric cancer. Although the basis for these diverse clinical outcomes is not understood, more severe disease is associated with strains harboring a pathogenicity island. To characterize the genetic diversity of more and less virulent strains, we examined the genomic content of 15 H. pylori clinical isolates by using a whole genome H. pylori DNA microarray. We found that a full 22% of H. pylori genes are dispensable in one or more strains, thus defining a minimal functional core of 1281 H. pylori genes. While the core genes encode most metabolic and cellular processes, the strain-specific genes include genes unique to H. pylori, restriction modification genes, transposases, and genes encoding cell surface proteins, which may aid the bacteria under specific circumstances during their long-term infection of genetically diverse hosts. We observed distinct patterns of the strain-specific gene distribution along the chromosome, which may result from different mechanisms of gene acquisition and loss. Among the strain-specific genes, we have found a class of candidate virulence genes identified by their coinheritance with the pathogenicity island. Keywords: other
2001-07-25 | GSE6 | GEO
Project description:Helicobacter pylori colonizes the stomach of half of the world's population, causing a wide spectrum of disease ranging from asymptomatic gastritis to ulcers to gastric cancer. Although the basis for these diverse clinical outcomes is not understood, more severe disease is associated with strains harboring a pathogenicity island. To characterize the genetic diversity of more and less virulent strains, we examined the genomic content of 15 H. pylori clinical isolates by using a whole genome H. pylori DNA microarray. We found that a full 22% of H. pylori genes are dispensable in one or more strains, thus defining a minimal functional core of 1281 H. pylori genes. While the core genes encode most metabolic and cellular processes, the strain-specific genes include genes unique to H. pylori, restriction modification genes, transposases, and genes encoding cell surface proteins, which may aid the bacteria under specific circumstances during their long-term infection of genetically diverse hosts. We observed distinct patterns of the strain-specific gene distribution along the chromosome, which may result from different mechanisms of gene acquisition and loss. Among the strain-specific genes, we have found a class of candidate virulence genes identified by their coinheritance with the pathogenicity island.
| S-EPMC18976 | biostudies-literature
Project description:Helicobacter pylori colonizes the stomach of half of the world's population, causing a wide spectrum of disease ranging from asymptomatic gastritis to ulcers to gastric cancer. Although the basis for these diverse clinical outcomes is not understood, more severe disease is associated with strains harboring a pathogenicity island. To characterize the genetic diversity of more and less virulent strains, we examined the genomic content of 15 H. pylori clinical isolates by using a whole genome H. pylori DNA microarray. We found that a full 22% of H. pylori genes are dispensable in one or more strains, thus defining a minimal functional core of 1281 H. pylori genes. While the core genes encode most metabolic and cellular processes, the strain-specific genes include genes unique to H. pylori, restriction modification genes, transposases, and genes encoding cell surface proteins, which may aid the bacteria under specific circumstances during their long-term infection of genetically diverse hosts. We observed distinct patterns of the strain-specific gene distribution along the chromosome, which may result from different mechanisms of gene acquisition and loss. Among the strain-specific genes, we have found a class of candidate virulence genes identified by their coinheritance with the pathogenicity island.
2001-07-25 | E-GEOD-6 | biostudies-arrayexpress
Project description:Helicobacter pylori is a genetically diverse and coevolved pathogen inhabiting human gastric niches and leading to a spectrum of gastric diseases in susceptible populations. We describe the genome sequence of H. pylori 908, which was originally isolated from an African patient living in France who suffered with recrudescent duodenal ulcer disease. The strain was found to be phylogenetically related to H. pylori J99, and its comparative analysis revealed several specific genome features and novel insertion-deletion and substitution events. The genome sequence revealed several strain-specific deletions and/or gain of genes exclusively present in HP908 compared with different sequenced genomes already available in the public domain. Comparative and functional genomics of HP908 and its subclones will be important in understanding genomic plasticity and the capacity to colonize and persist in a changing host environment.
| S-EPMC3008520 | biostudies-literature
Project description:Helicobacter pylori colonizes about half of the world's population. It is a causative agent of stomach diseases, including malignant tumors. We report the genome sequence of strain N6, which is widely used in H. pylori research and appreciated for its large cell size and high transformation efficiency.
| S-EPMC3393512 | biostudies-other
Project description:High genetic diversity is a hallmark of the gastric pathogen Helicobacter pylori. We used 454 sequencing technology to perform whole-genome comparisons for five sets of H. pylori strains that had been sequentially cultured from four chronically infected Colombians (isolation intervals=3-16 y) and one human volunteer experimentally infected with H. pylori as part of a vaccine trial. The four sets of genomes from Colombian H. pylori differed by 27-232 isolated SNPs and 16-441 imported clusters of polymorphisms resulting from recombination. Imports (mean length=394 bp) were distributed nonrandomly over the chromosome and frequently occurred in groups, suggesting that H. pylori first takes up long DNA fragments, which subsequently become partially integrated in multiple shorter pieces. Imports were present at significantly increased frequency in members of the hop family of outer membrane gene paralogues, some of which are involved in bacterial adhesion, suggesting diversifying selection. No evidence of recombination and few other differences were identified in the strain pair from an infected volunteer, indicating that the H. pylori genome is stable in the absence of mixed infection. Among these few differences was an OFF/ON switch in the phase-variable adhesin gene hopZ, suggesting strong in vivo selection for this putative adhesin during early colonization.
| S-EPMC3064335 | biostudies-literature
Project description:Although the type 4 secretion system of the integrating and conjugative elements (tfs ICE) is common in Helicobacter pylori, its clinical association with the cag pathogenicity island (cagPAI) have not yet been well-investigated. In this study, Vietnamese patient H. pylori samples (46 duodenal ulcer (DU), 51 non-cardia gastric cancer (NCGC), 39 chronic gastritis (CG)) were fully sequenced using next-generation sequencing and assembled into contigs. tfs3, tfs4, and cagPAI genes were compared with the public database. Most (94%) H. pylori strains possessed a complete cagPAI, which was the greatest risk factor for clinical outcomes, while the prevalences of tfs3 and tfs4 were 45% and 77%, respectively. Complete tfs3 and tfs4 were found in 18.3% and 17.6% of strains, respectively. The prevalence of H. pylori strains with complete tfs3 ICE in DU patients was significantly higher than that in NCGC patients (30.4% vs 11.7%, P < 0.05). In addition, the prevalence of strains with complete tfs3 ICE and cagPAI was significantly higher in DU patients than that in NCGC (28.4% vs 9.8%, P = 0.038) and CG patients (28.2% vs 7.7%, P = 0.024). cagPAI and complete tfs3 increased the risk of DU compared to NCGC (OR = 3.56, 95%CI: 1.1-14.1, P = 0.038) and CG (OR = 4.64, 95%CI: 1.1-27.6, P = 0.024). A complete cluster of tfs3 ICE was associated with gastroduodenal diseases in Vietnam. However, there was a low prevalence of the dupA/complete dupA cluster (15.4%) in the Vietnam strains. The prevalence of cagPAI in Vietnam strains was significantly higher than in US (P = 0.01) and Indonesia (P < 0.0001); the prevalence of the dupA cluster was also higher in the Vietnam strains than in the Indonesian strains (P < 0.05). In addition, the prevalence of ctkA, an accessory gene of tfs3, was significantly different between Vietnam and US strains (28% vs 2%, P = 0.0002). In summary, the acquisition of tfs3/4 ICE was common in H. pylori strains in patients with gastroduodenal disease in Vietnam, and the complete cluster of tfs3 ICE was a reliable marker for the severity of disease in the H. pylori infected population.
| S-EPMC7907105 | biostudies-literature
Project description:Many organisms respond to DNA damage by inducing expression of DNA repair genes. We find that the human stomach pathogen Helicobacter pylori instead induces transcription and translation of natural competence genes, thus increasing transformation frequency. Transcription of a lysozyme-like protein that promotes DNA donation from intact cells is also induced. Exogenous DNA modulates the DNA damage response, as both recA and the ability to take up DNA are required for full induction of the response. This feedback loop is active during stomach colonization, indicating a role in the pathogenesis of the bacterium. As patients can be infected with multiple genetically distinct clones of H. pylori, DNA damage induced genetic exchange may facilitate spread of antibiotic resistance and selection of fitter variants through re-assortment of preexisting alleles in this important human pathogen.
| S-EPMC2912397 | biostudies-literature
Project description:UNLABELLED:Helicobacter pylori chronically infects the gastric mucosa in more than half of the human population; in a subset of this population, its presence is associated with development of severe disease, such as gastric cancer. Genomic analysis of several strains has revealed an extensive H. pylori pan-genome, likely to grow as more genomes are sampled. Here we describe the draft genome sequence (63 contigs; 26× mean coverage) of H. pylori strain B45, isolated from a patient with gastric mucosa-associated lymphoid tissue (MALT) lymphoma. The major finding was a 24.6-kb prophage integrated in the bacterial genome. The prophage shares most of its genes (22/27) with prophage region II of Helicobacter acinonychis strain Sheeba. After UV treatment of liquid cultures, circular DNA carrying the prophage integrase gene could be detected, and intracellular tailed phage-like particles were observed in H. pylori cells by transmission electron microscopy, indicating that phage production can be induced from the prophage. PCR amplification and sequencing of the integrase gene from 341 H. pylori strains from different geographic regions revealed a high prevalence of the prophage (21.4%). Phylogenetic reconstruction showed four distinct clusters in the integrase gene, three of which tended to be specific for geographic regions. Our study implies that phages may play important roles in the ecology and evolution of H. pylori. IMPORTANCE:Helicobacter pylori chronically infects the gastric mucosa in more than half of the human population, and while most of the infected individuals do not develop disease, H. pylori infection doubles the risk of developing gastric cancer. An abundance and diversity of viruses (phages) infect microbial populations in most environments and are important mediators of microbial diversity. Our finding of a 24.6-kb prophage integrated inside an H. pylori genome and the observation of circular integrase gene-containing DNA and phage-like particles inside cells upon UV treatment demonstrate that we have discovered a viable H. pylori phage. The additional finding of integrase genes in a large proportion of screened isolates of diverse geographic origins indicates that the prevalence of prophages may have been underestimated in H. pylori. Since phages are important drivers of microbial evolution, the discovery should be important for understanding and predicting genetic diversity in H. pylori.
| S-EPMC3221604 | biostudies-literature