title: Two-year follow-up of Helicobacter pylori infection in C57BL/6 and Balb/cA mice.
abstract: Helicobacter pylori infection is associated with chronic gastritis, peptic ulcer disease, gastric adenocarcinoma and MALT lymphoma. We previously found high-grade lymphoma after 13 months' H. pylori infection in C57BL/6 mice. In this study we followed H. pylori infection by three different isolates in C57BL/6 and Balb/cA mice for 23 months. Six-week-old C57BL/6 and Balb/cA mice were infected with H. pylori strains 119p (CagA+, VacA+), SS1 (CagA+, VacA+) and G50 (CagA-, VacA-). Mice were followed at 2 weeks, 10 weeks and 23 months post-inoculation (p.i.) by culture, histopathology and serology. Strain G50 was only reisolated from mice 2 weeks p.i. There was no difference in colonization between strain 119p and SS1 at 10 weeks p.i., whereas SS1 gave 100% colonization versus 119p gave 50% 23 months p.i. Interestingly, the inflammation score was higher in mice infected with strain 119p than with SS1 10-week p.i., and there were lymphoepithelial lesions in mice infected with strain 119p and G50 but not with SS1 at 23 months post-infection. Eight mice infected with strains 119p and G50 developed gastric lymphoma (grade 5 and 4). One C57BL/6 mouse infected with strain 119p developed hepatocellular carcinoma after 23 months. Immunoblot showed specific bands of 26-33 kDa against H. pylori in infected mice, and two mice infected with strain SSI reacted with antibodies to the 120 kDa CagA toxin.
  
  
  CONCLUSIONS
  A reproducible animal model for H. pylori-induced lymphoma and possibly hepatocellular carcinoma is described. Strain diversity may lead to different outcomes of H. pylori infection.
authors.affiliation: Department of Medical Microbiology, University of Lund, Lund, Sweden.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.forename: Roger
authors.initials: R
authors.lastname: Willén
authors.forename: Marie
authors.initials: M
authors.lastname: Svensson
authors.forename: Asa
authors.initials: A
authors.lastname: Ljungh
authors.forename: Torkel
authors.initials: T
authors.lastname: Wadström
mesh_terms: D000818:Animals; D001706:Biopsy; D006528:Carcinoma, Hepatocellular / Q000382:microbiology; D004195:Disease Models, Animal; D005500:Follow-Up Studies; D016481:Helicobacter Infections / Q000150:complications / Q000382:microbiology / Q000473:pathology*; D016480:Helicobacter pylori / Q000254:growth & development*; D008113:Liver Neoplasms / Q000382:microbiology; D008223:Lymphoma / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D013272:Stomach Diseases / Q000150:complications / Q000382:microbiology* / Q000473:pathology