Virulence Factors of Helicobacter pylori

Helicobacter pylori is a Gram-negative bacterium living in the stomach of its human host. The infection causes chronic gastric mucosal inflammation and is etiologically related to gastritis-associated diseases, gastric cancer and peptic ulcer disease. As with other chronic infectious diseases associated with a long latent period (e.g., syphilis and tuberculosis), clinical manifestations develop in only a minority of infected individuals. The outcome for any of these diseases is dependent on the interplay between host, environmental, and bacterial factors. The variable virulence of H. pylori in relation to the presence or absence of a specific virulence factor reflects the differences in risk of a clinical outcome. The best-studied virulence factors are the vacuolating cytotoxin A (VacA) and cytotoxin-associated gene A product (CagA). This chapter will discuss the clinical relevance of typing H. pylori virulence factors CagA and VacA. Approximately 1,600 genes make up the H. pylori genome suggesting that there may be other unidentified virulence factors, many likely to be discovered using whole-genome sequencing.

Keywords: Helicobacter pylori, gastric cancer, peptic ulcer, virulence factors, vacuolating cytotoxin (VacA), cytotoxin-associated gene A product (CagA), nextgeneration sequencers.