Virulence mechanisms of helicobacter pylori: An overview

Helicobacter pylori is a highly successful human pathogen, able to establish a chronic infection in the harsh environment of the stomach. These bacteria express a variety of virulence factors that promote their survival under acidic conditions, motility and spatial orientation in gastric mucus and adherence to epithelial cells. Other pathogenicity-associated mechanisms contribute to chronic gastritis by inducing pro-inflammatory responses and by manipulating cellular responses in host cells. Although H. pylori elicits a strong inflammatory response, the immune system fails to clear the infection. The pathogen employs a range of evasion strategies to dampen or reduce host immune responses. These strategies enable H. pylori to establish an equilibrium with its host, so that the vast majority of the chronically infected individuals do not develop severe disease. However, in a subset of patients, disturbance of this equilibrium in favour of the pathogen may lead to the development of gastroduodenal ulceration, mucosa-associated lymphoid tissue (MALT) lymphoma or adenocarcinoma.