Helicobacter pylori strains and their relationship with vacuolating cytotoxin A gene in the increased risk of gastric cancer

Abstract

Objectives: The main objective of this study is to analyze the relationship of H. pylori vacuolating gene in gastric cancer. Methods: H. pyroli strains were isolated from the biopsy specimens collected from 50 patients suspected of gastritis, gastric carcinoma and peptic ulcer disease. H. pylori JK was identified and the virulence gene was determined. The presence of vacuolating cytotoxin A gene was amplified using a polymerase chain reaction. The growth kinetics of the strain JK were evaluated up to 96 h at 37 °C and the culture was used for the determination of VacA gene expression. Results: The screened H. pylori JK was positive for vacA gene and showed heterogeneity among H. pylori. Bacterial growth increased up to 48 h incubation and declined after 48 h. The isolated strain showed maximum growth after 72 h incubation, whereas, the toxic protein reached maximum yield after 96 h incubation and was not associated with growth. It was resistant to antibiotics such as ceftriaxone, cefuroxime, cefalexin, and co-trimoxazole. The intracellular H. pylori culture extracts induced vacuolation in HeLa cell lines in vitro. The isolated H. pylori strain showed more than 43% vacuolating activity after 24 h incubation. Immunoblotting assay revealed the presence of an immuno-reactive protein band in the culture supernatant of H. pylori JK. These results indicated the pathogenic activity of the VacA gene and toxin production. Conclusions: Generally, H. pylori persists for the lifetime of the individual, revealing the significance of eradication from the host.

Keywords

• Gastric cancer
• H. pylori
• Drug resistance
• vacA gene
• Expression
• Toxic protein