title: Characteristics of a clinical isolate of urease-negative Helicobacter pylori and its ability to induce gastric ulcers in Mongolian gerbils.
abstract: BACKGROUND
  We clinically obtained urease-negative mutant strains of Helicobacter pylori. The goal of this study was to investigate the ability of the urease-negative strain to colonize and subsequently damage the gastric mucosa in Mongolian gerbils. In addition, the genes encoding the urease production in the test strain were analyzed, and other genes encoding the virulence factors, cytotoxin-associated protein and vacuolating-cytotoxin were evaluated.
  
  
  METHODS
  The character of urease-negative isolates of H. pylori was defined. The identification of H. pylori was confirmed by polymerase chain reaction (PCR). The H. pylori isolate was transfected into Mongolian gerbils as previously described, which were followed up to 42 weeks, and the changes in their gastric mucosa were examined histologically.
  
  
  CONCLUSIONS
  Fifteen Mongolian gerbils orally infected with 10(7) colony forming units of urease-negative H. pylori were killed at 4, 12, 24, 36 and 42 weeks (n = 3) after infection. Culture medium without urease-negative H. pylori was given to the Mongolian gerbils as control. H. pylori continued to exist in the subject's stomach and gastric ulceration was observed and compared with the control. Clinically obtained urease-negative H. pylori continued to exist for at least 42 weeks in the subject's stomach and it induced gastric ulcers. These data demonstrated that the urease in H. pylori was not a necessary factor in the formation of gastric ulcers in the Mongolian gerbil model.
authors.affiliation: Department of Internal Medicine, University of Tokai School of Medicine, Bohseidai, Isehara, Kanagawa 259-1193, Japan. tetsu-m@is.icc.u-tokai.ac.jp
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Mine
authors.forename: Hiroe
authors.initials: H
authors.lastname: Muraoka
authors.forename: Takeshi
authors.initials: T
authors.lastname: Saika
authors.forename: Intetsu
authors.initials: I
authors.lastname: Kobayashi
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005753:Gastric Mucosa / Q000382:microbiology / Q000473:pathology; D005798:Genes, Bacterial; D005849:Gerbillinae; D016481:Helicobacter Infections / Q000150:complications*; D016480:Helicobacter pylori / Q000235:genetics / Q000472:pathogenicity*; D006801:Humans; D008297:Male; D009154:Mutation; D016133:Polymerase Chain Reaction; D013276:Stomach Ulcer / Q000209:etiology* / Q000382:microbiology / Q000473:pathology; D014510:Urease / Q000235:genetics; D014774:Virulence
chemical_list: D014510:Urease