Helicobacter pylori: molecular detection of vacA gene and vacuolating activity in human gastric adenocarcinoma cells

Background and Aims. Helicobacter pylori strains secrete a vacuolating cytotoxin (VacA), plays an important role for the development of peptic ulcer disease and gastro-duodenal diseases. vacA gene is responsible to regulate the activity of the vacuolating cytotoxin. The objective of this study was molecular detection of vacA gene and observes the vacuolating activity on human gastric adenocarcinoma (AGS) cells. Materials and Methods. H. pylori vacA gene was determined by polymerase chain reaction. Vacuolation activity of VacA toxin in broth culture filtrates was assessed in AGS cells and quantified by neutral uptake assay. Different concentration dosages of VacA and incubation time were used in the measurement of the vacuolating activity on AGS cells. Results. The results showed that VacA toxin could stimulate vacuolating activity on AGS cells with minimum concentration 1.0 mu g/ml from both of s1m1 and s1m2 alleles (vacA gene). The toxin produced optimal reaction at 5.0 mu g/ml with significant differences observed between the alleles. The results also showed that both alleles commenced the vacuolating activity at the minimum of 3 hr incubation time, and the activity showed in time-dependent manner. Conclusion. Optimal concentration of VacA toxin (s1m1 allele) causes more interaction with AGS cell producing more vacuolating activities. Time-dependent vaculation of both alleles might allow H. pylori for persistent infection without rapid destruction of gastric cells might promote gastro-duodenal diseases. The study provided us better understanding of the pathogenesis of the diseases associated with H. pylori infection which is an emerging problem in developing countries.