Helicobacter pylori determinants of pathogenicity

The bacterium Helicobacter pylori colonises the stomach of man and induces a strong inflammatory response. Differences in the possession of pathogenic ity determinants by H. pylori isolates could account in part for the differ ent clinical outcomes of infection. The main H. pylori pathogenic factors, i.e. urease, the cytotoxin VacA, and the genes involved in virulence contai ned in the pathogenicity island (PAI) cag, may promote tissue damage and ul ceration, and could contribute to gastric cancer development. Strains with the mosaic vacA allelic type s1a/m1 and possessing the cag insertion are co nsidered endowed with increased inflammatory potential, and are more likely to be isolated from patients with peptic ulcer and gastric cancer. The pre sence in H. pylori cag PAI of operons involved in the stimulation of gastri c epithelial cells to secrete high levels of inflammatory cytokines, in mob ilisation of DNA, and formation of secretory mechanisms and conjugation app arati, could contribute to increase the risk of gastric cancer development in patients infected by this microorganism.