Abstract
Prevalence of Helicobacter pylori infection in Nepal, a low-risk country for gastric cancer, is debatable. To our knowledge, no studies have examined H. pylori virulence factors in Nepal. We determined the prevalence of H. pylori infection by using three different tests, and the genotypes of virulence factors were determined by PCR followed by sequencing. Multilocus sequence typing was used to analyze the population structure of the Nepalese strains. The prevalence of H. pylori infection in dyspeptic patients was 38.4% (56/146), and was significantly related with source of drinking water. In total, 51 strains were isolated and all were cagA-positive. Western-type-cagA (94.1%), cagA pre-EPIYA type with no deletion (92.2%), vacA s1a (74.5%), and m1c (54.9%) were the predominant genotypes. Antral mucosal atrophy levels were significantly higher in patients infected with vacA s1 than in those infected with s2 genotypes (P = 0.03). Several Nepalese strains were H. pylori recombinants with genetic features of South Asian and East Asian genotypes. These included all East-Asian-type-cagA strains, with significantly lesser activity and inflammation in the corpus than the strains of the specific South Asian genotype (P = 0.03 and P = 0.005, respectively). Although the population structure confirmed that most Nepalese strains belonged to the hpAsia2 population, some strains shared hpEurope- and Nepalese-specific components. Nepalese patients infected with strains belonging to hpEurope showed higher inflammation in the antrum than strains from the Nepalese specific population (P = 0.05). These results support that ancestor roots of Kathmandu`s people not only connected with India alone.
Highlights
Helicobacter pylori, a major pathogen of the gastrointestinal tract, has been implicated in a wide spectrum of gastric disorders, including gastritis, peptic ulcer, gastric cancer, and mucosa-associated lymphoid tissue lymphoma [1,2]
H. pylori infection is a major factor in the development of gastric cancer [4], the difference in H. pylori infection rate between countries is not enough to explain the difference in the incidence of gastric cancer in the world
Patients were considered to be negative for H. pylori infection when all three test results were negative, whereas patients with at least one positive test result were considered positive for H. pylori infection
Summary
Helicobacter pylori, a major pathogen of the gastrointestinal tract, has been implicated in a wide spectrum of gastric disorders, including gastritis, peptic ulcer, gastric cancer, and mucosa-associated lymphoid tissue lymphoma [1,2]. H. pylori infection is a major factor in the development of gastric cancer [4], the difference in H. pylori infection rate between countries is not enough to explain the difference in the incidence of gastric cancer in the world. The pre-EPIYA region, located about 300 base pairs (bp) upstream of the first EPIYA motif, has been investigated as a virulence factor. Alignment of these sequences revealed that a 39 bp deletion was present in most strains isolated from East Asia, but was absent in most strains from Western countries (nondeletion type) [8]
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