A standardized mouse model of Helicobacter pylori infection: Introducing the Sydney strain

Background & Aims: Currently available Helicobacter as adjuvant showed protection against challenge with pylori models show variable and, in some instances, living H. felis organisms. 10Later H. pylori antigens were poor colonization.There is a need for a strain with shown to protect against the feline bacterium. 11,12 The high colonizing ability to act as a standard for animal first demonstrations of therapeutic immunization were studies.Methods: After screening a range of fresh clinialso reported with the H. felis model. 13,14 cal isolates and long-term adaptation in mice, a strainRecently, there has been some success in the developof H. pylori has been isolated with a very good colonizment of a mouse model using human strains of H. pylori.ing ability.Results: This strain, named the Sydney Japanese studies achieved successful colonization of nude strain of H. pylori (strain SS1), is cagA and vacA posimice with H. pylori, a model subsequently used for antitive.High levels of colonization (10 6 -10 7 colony-forming units/g tissue) were achieved consistently in microbial screening. 15,16 More importantly, Marchetti et C57BL/6 mice.Colonization levels varied depending al. used a mouse-adapted strain in vaccine studies with on the mouse strain used with BALB/c, DBA/2, andVacA protein antigen and the adjuvant heat-liable toxin C3H/He, all being colonized but in lower numbers.In of Escherichia coli. 17However, the level of colonization in all strains of mice, bacteria were clearly visible at the these studies was very low.Colony counts were minimal junctional zone between the antrum and the body.The (i.e., fewer than 100 colonies per infected mouse), and phenotype was stable with colonizing ability remaining bacteria could not be easily observed by microscopy.after 20 subcultures in vitro.The bacterium attached With such poor colonization, it was difficult to assess firmly to gastric epithelium.During 8 months, a chronic how comparable this model was to human infection.active gastritis slowly developed, progressing to severe None of the published H. pylori models has shown conatrophy in both C57BL/6 and BALB/c mice.Concluvincing pictures of bacteria in the gastric mucosa, which sions: The Sydney strain of H. pylori is available to all presumably means they could not be easily observed.and will provide a standardized mouse model for vaccine development, compound screening, and studies This is a concern because it would seem essential that in pathogenesis.bacteria are visible in large numbers, as is observed in H. felis-infected animals and on the H. pylori-infected human gastric mucosa.