Helicobacter pylori (H. pylori), is the most common infectious bacterium of the Human stomach. In early childhood, colonization of H. pylori in stomach releases different pathogenic factors which interfere with functions of human cells. Combination of two main genetic pathogenic factors CagA and VacA play important role in causing severity of H. pylori infection. In H. pylori infected patients, CagA and CagPAI positive strains have positive association in development of peptic ulcer disease and gastric cancers.50-70% of H. pylori produces CagA gene that is multifunction toxin. By adapting different mechanisms CagA define its role in oncogenic signaling cascades, in tumor suppressor pathway and in inflammation. CagA gene is strongly associated with VacA cytotoxic function and the strains, ultimately responsible for epithelial destruction of stomach and leading towards cancer. Review provides, CagA has important role in the virulence of H.pylori infection. Different Peptic ulcer diseases and gastric cancers are caused by the presence of CagA gene.
Key words: H. pylori, CagA gene, VacA gene, Gastric cancers, Peptic ulcer disease.