Query: NC_004917:946550 Helicobacter hepaticus ATCC 51449, complete genome
Lineage: Helicobacter hepaticus; Helicobacter; Helicobacteraceae; Campylobacterales; Proteobacteria; Bacteria
General Information: This organism was found to be linked to an increasing incidence of liver tumors in mouse colonies at the National Cancer Institute in 1992. Normally it resides in the lower intestines, but it can cause chronic hepatitis. This organism has a similar urease gene cluster and cytolethal distending toxin as compared to Helicobacter pylori, but lacks other virulence factors such as the vacuolating cytotoxin and the cag pathogenicity island. However, it does contain a pathogenicity island that encodes proteins similar to those found in a type IV secretion system. Causes liver disease. This genus consists of organisms that colonize the mucosal layer of the gastrointestinal tract or are found enterohepatically (in the liver). This species was associated with an increase in liver tumors. It can cause active chronic hepatitis and typhlitis (inflammation of a region at the beginning of the large intestine), hepatocellular tumors, and gastric bowel disease in various mice strains.
Subject: NC_000921:1007519 Helicobacter pylori J99, complete genome
Lineage: Helicobacter pylori; Helicobacter; Helicobacteraceae; Campylobacterales; Proteobacteria; Bacteria
General Information: This strain was isolated in 1994 in the USA from a patient with duodenal ulcer. This genus consists of organisms that colonize the mucosal layer of the gastrointestinal tract or are found enterohepatically (in the liver). It was only recently discovered (1983) by two Australians (Warren and Marshall) that this organism was associated with peptic ulcers. It is one of the most common chronic infectious organisms, and is found in half the world's population. This organism attacks the gastric epithilial surface, resulting in chronic gastritis, and can cause more severe diseases including those that lead to gastric carcinomas and lymphomas, peptic ulcers, and severe diarrhea. It is an extracellular pathogen that persists in the gastric environment, which has a very low pH, by production of the urease enzyme, which converts urea to ammonia and carbon dioxide, a process which can counteract the acidic environment by production of a base. The toxins include cytolethal distending toxin, vacuolating cytotoxin (VacA) that induces host epithelial cell apopoptosis (cell death), and the cytotoxin associated antigen (CagA) which results in alteration to the host cell signalling pathways. The CagA protein is translocated into host cells by a type IV secretion system encoded by the cag pathogenicity island.