[Helicobacter pylori and the others]

Since the discovery of H. pylori, several new Helicobacter species have been isolated from man and mainly from animals. Helicobacter species can be broadly grouped according to whether they colonize the gastric or enterohepatic niche. H. pylori is a bacterium of great clinical importance, essentially in the domain of gastroenterology. H. pylori infection is the first chronic infection known to give rise to cancer in man (gastric carcinoma and MALT lymphoma). The pathogenesis of H. pylori is now well studied. Two H. pylori strains have been sequenced: the first one isolated from a patient with gastric ulcer, the second one associated with gastritis. Global analysis of the gene content of H. pylori strains gives insight into the extent of its genetic diversity. Substantial evidence attests to certain extragastric Helicobacter species playing a role in the pathogenesis of enteric, hepatic and biliary disorders, especially for H. hepaticus which have just been sequenced. But isolation of non-pylori Helicobacter species continues to be a major problem, substantially limiting a better understanding of their prevalence and role. Therefore, animal models are of interest because of their value for modeling human disease and testing therapeutic strategies such as vaccines.