The study of virulence factor for Helicobacter pylori isolates from Mongolia

Abstract

Background: Mongolia is the world leading country by the gastric cancer morbidity and mortality. In particular, in terms of geographical location, gastric cancer is more common in the western regions of Mongolia. The main etiology of gastric cancer is considered to be H. pylori infection. The lack of research on the prevalence of H. pylori and cancer risk factors in different geographical regions of Mongolia is the basis of our study. Aim: To study the characteristics of H. pylori infection at the molecular biological level, which is the main cause of gastric cancer in the Mongolian population. Materials and Methods: In 2014-2018, a total of 905 people with dyspeptic syndrome aged 16 and over were surveyed in different geographical areas of Mongolia. Clinical examination was based on questionnaires, endoscopy, and histology. H. pylori was cultured and the CagA and VacA genes were determined by PCR. Results:The prevalence of H. pylori infection is 77.5% in Ulaanbaatar (154/206), 77.5% in Uvs aimag (93/120), 78.4% in Khuvsgul (134/171), 87.1% (108/124) in Umnugovi aimag, and 87% in Khentii ( 100/115) are distributed, respectively. In a total of 368 cases of isolated H. pyloristrains, the CagA-positivite strains were 83.2% (306/368) and 16.8% (62/368) were cagA-negative. For the VacA gene subtype, S1M1 was 53.3% (196/368), S1M2 was 27.1% (100/368), S2M1 was 1.1% (4/368), and S2M2 was 18.4% (68/368). Conclusions:The prevalence of H. pylori infection is high. The virulence of H. pylori is dominated by the Western-type genotype in 95.8% of the CagA genes, which is very different from other Asian countries, indicating the need for further in-depth study.