Abstract
Helicobacter pylori are 'slow' bacteria that may cause disease decades after acquisition. Bacterial pathogenesis often involves features, including conserved genes, shared by many different species. As such, despite its unique niche in the human body, the pathogenesis of H. pylori infection most likely shares mechanisms with other bacteria. In this paper, two genes, vacA and cagA, which appear unique to H. pylori and which may reflect the particular requirements of H. pylori for long-term residence in the human stomach will be discussed. At present the function of these genes for H. pylori is not known yet other characteristics have been defined.