Genome sequences of three Helicobacter pylori strains isolated from atrophic gastritis and gastric ulcer patients in China

Rapid diagnosis and precision treatment of Helicobacter pylori infection in clinical settings

Helicobacter pylori is a gram-negative bacterium that colonizes the stomach of approximately half of the worldwide population, with higher prevalence in densely populated areas like Asia, the Caribbean, Latin America, and Africa. H. pylori infections range from asymptomatic cases to potentially fatal diseases, including peptic ulcers, chronic gastritis, and stomach adenocarcinoma. The management of these conditions has become more difficult due to the rising prevalence of drug-resistant H. pylori infections, which ultimately lead to gastric cancer and mucosa-associated lymphoid tissue (MALT) lymphoma. In 1994, the International Agency for Research on Cancer (IARC) categorized H. pylori as a Group I carcinogen, contributing to approximately 780,000 cancer cases annually. Antibiotic resistance against drugs used to treat H. pylori infections ranges between 15% and 50% worldwide, with Asian countries having exceptionally high rates. This review systematically examines the impacts of H. pylori infection, the increasing prevalence of antibiotic resistance, and the urgent need for accurate diagnosis and precision treatment. The present status of precision treatment strategies and prospective approaches for eradicating infections caused by antibiotic-resistant H. pylori will also be evaluated.

Helicobacter pylori's historical journey through Siberia and the Americas

The peopling of Siberia and the Americas is intriguing for archaeologists, linguists, and human geneticists, but despite significant recent developments, many details remain controversial. Here, we provide insights based on genetic diversity within Helicobacter pylori, a bacterium that infects 50% of all humans. H. pylori strains were collected from across eastern Eurasia and the Americas. Sequence analyses indicated that Siberia contains both anciently diverged and recently admixed bacteria, supporting both human persistence over the last glacial maximum and more recent human recolonization. We inferred a single migration across the Bering land bridge, accompanied by a dramatic reduction in effective population size, followed by bidirectional Holocene gene flow between Asia and the Americas.

The gastric bacterium Helicobacter pylori shares a coevolutionary history with humans that predates the out-of-Africa diaspora, and the geographical specificities of H. pylori populations reflect multiple well-known human migrations. We extensively sampled H. pylori from 16 ethnically diverse human populations across Siberia to help resolve whether ancient northern Eurasian populations persisted at high latitudes through the last glacial maximum and the relationships between present-day Siberians and Native Americans. A total of 556 strains were cultivated and genotyped by multilocus sequence typing, and 54 representative draft genomes were sequenced. The genetic diversity across Eurasia and the Americas was structured into three populations: hpAsia2, hpEastAsia, and hpNorthAsia. hpNorthAsia is closely related to the subpopulation hspIndigenousAmericas from Native Americans. Siberian bacteria were structured into five other subpopulations, two of which evolved through a divergence from hpAsia2 and hpNorthAsia, while three originated though Holocene admixture. The presence of both anciently diverged and recently admixed strains across Siberia support both Pleistocene persistence and Holocene recolonization. We also show that hspIndigenousAmericas is endemic in human populations across northern Eurasia. The evolutionary history of hspIndigenousAmericas was reconstructed using approximate Bayesian computation, which showed that it colonized the New World in a single migration event associated with a severe demographic bottleneck followed by low levels of recent admixture across the Bering Strait.

Comparative genomics of a Helicobacter pylori isolate from a Chinese Yunnan Naxi ethnic aborigine suggests high genetic divergence and phage insertion

Helicobacter pylori is a common pathogen correlated with several severe digestive diseases. It has been reported that isolates associated with different geographic areas, different diseases and different individuals might have variable genomic features. Here, we describe draft genomic sequences of H. pylori strains YN4-84 and YN1-91 isolated from patients with gastritis from the Naxi and Han populations of Yunnan, China, respectively. The draft sequences were compared to 45 other publically available genomes, and a total of 1059 core genes were identified. Genes involved in restriction modification systems, type four secretion system three (TFS3) and type four secretion system four (TFS4), were identified as highly divergent. Both YN4-84 and YN1-91 harbor intact cag pathogenicity island (cagPAI) and have EPIYA-A/B/D type at the carboxyl terminal of cagA. The vacA gene type is s1m2i1. Another major finding was a 32.5-kb prophage integrated in the YN4-84 genome. The prophage shares most of its genes (30/33) with Helicobacter pylori prophage KHP30. Moreover, a 1,886 bp transposable sequence (IS605) was found in the prophage. Our results imply that the Naxi ethnic minority isolate YN4-84 and Han isolate YN1-91 belong to the hspEAsia subgroup and have diverse genome structure. The genome has been extensively modified in several regions involved in horizontal DNA transfer. The important roles played by phages in the ecology and microevolution of H. pylori were further emphasized. The current data will provide valuable information regarding the H. pylori genome based on historic human migrations and population structure.

Helicobacter pylori genetic diversity and gastro-duodenal diseases in Malaysia

Helicobacter pylori infection results in diverse clinical conditions ranging from chronic gastritis and ulceration to gastric adenocarcinoma. Among the multiethnic population of Malaysia, Indians consistently have a higher H. pylori prevalence as compared with Chinese and Malays. Despite the high prevalence of H. pylori, Indians have a relatively low incidence of peptic ulcer disease and gastric cancer. In contrast, gastric cancer and peptic ulcer disease incidence is high in Chinese. H. pylori strains from Chinese strains predominantly belong to the hspEAsia subpopulation while Indian/Malay strains mainly belong to the hspIndia subpopulation. By comparing the genome of 27 Asian strains from different subpopulations, we identified six genes associated with risk of H. pylori-induced peptic ulcer disease and gastric cancer. This study serves as an important foundation for future studies aiming to understand the role of bacterial factors in H. pylori-induced gastro-duodenal diseases.

Genomic characterization of a Helicobacter pylori isolate from a patient with gastric cancer in China

Background

Helicobacter pylori is well known for its relationship with the occurrence of several severe gastric diseases. The mechanisms of pathogenesis triggered by H. pylori are less well known. In this study, we report the genome sequence and genomic characterizations of H. pylori strain HLJ039 that was isolated from a patient with gastric cancer in the Chinese province of Heilongjiang, where there is a high incidence of gastric cancer. To investigate potential genomic features that may be involved in pathogenesis of carcinoma, the genome was compared to three previously sequenced genomes in this area.

Result

We obtained 42 contigs with a total length of 1,611,192 bp and predicted 1,687 coding sequences. Compared to strains isolated from gastritis and ulcers in this area, 10 different regions were identified as being unique for HLJ039; they mainly encoded type II restriction-modification enzyme, type II m6A methylase, DNA-cytosine methyltransferase, DNA methylase, and hypothetical proteins. A unique 547-bp fragment sharing 93% identity with a hypothetical protein of Helicobacter cinaedi ATCC BAA-847 was not present in any other previous H. pylori strains. Phylogenetic analysis based on core genome single nucleotide polymorphisms shows that HLJ039 is defined as hspEAsia subgroup, which belongs to the hpEastAsia group.

Conclusion

DNA methylations, variations of the genomic regions involved in restriction and modification systems, are the “hot” regions that may be related to the mechanism of H. pylori-induced gastric cancer. The genome sequence will provide useful information for the deep mining of potential mechanisms related to East Asian gastric cancer.

Helicobacter pylori in 2013: multiplying genomes, emerging insights

We describe features of key additions to the existing pool of publicly accessible Helicobacter pylori genome sequences and sequences of Helicobacter pylori phages from April 2012 to March 2013. In addition, important studies involving H. pylori genomes, especially those pertaining to genomic diversity, disease outcome, H. pylori population structure and evolution are reviewed. High degree of homologous recombination contributes to increased diversity of H. pylori genomes. New methods of resolving H. pylori population structure to an ultrafine level led to the proposal of new subpopulations. As the magnitude of diversity in the H. pylori gene pool becomes more and more clear, geographic and demographic factors should be brought to analysis while identifying disease-specific biomarkers and defining new virulence mechanisms.