Molecular characterisation of virulent gene vacA in Helicobacter pylori clinical isolates from patients with gastroduodenal diseases in Assam, India

Background: Helicobacter pylori, the gastric bacterium, is widely known to be one of the most genetically diverse group of organisms whose pathogenesis as well as the diversity in infection outcome may be attributed to a variety of virulent genes. Aim: This study aimed to study the molecular profile of H. pylori vacA gene by determining the phylogenetic relatedness and genetic diversity of the strains isolated in this region with those of other geographical regions. Materials and Methods: A total of twenty H. pylori clinical strains were isolated from randomly selected 100 patients suffering from gastroduodenal diseases as well as endoscopically normal patients in a cross-sectional hospital-based setting from January 2016 to May 2017. VacA signal sequence and mid regions of H. pylori were amplified by polymerase chain reaction followed by DNA sequencing and phylogenetic analysis. Results: VacA s1m1 allelic variant was more prevalent in our study, regardless of the clinical outcomes. Phylogenetic analysis of VacA s1 strains revealed clustering of most of the strains. VacA m1 strains clustered with Bangladesh strains which is a country nearest to India. Conclusion: Prevalence of VacA s1m1 strains may account for high risk of transmission of this gastric pathogen and the overall risk of acquiring infection. Phylogenetic analysis results suggests the prevalence of high genetic diversity in our region. Our findings may aid in developing a better understanding of the genetic structure of H. pylori and the pathophysiology of associated diseases, thus facilitating the implementation of various treatment options.