EXPERIMENTAL-INFECTION OF MONGOLIAN GERBILS WITH WILD-TYPE AND MUTANTHELICOBACTER-PYLORI STRAINS

Experimental Helicobacter. pylori infection a-as studied in Mongolian gerbils with fresh human isolates that early or do not carry cagA (cag 4-positive or cagA-negative, respectively), multiply passaged laborato ry strains, wild-type strain G1.1, or isogenic ureA, cagA, or vacA mut ants of G1.1. Animals were sacrificed 1 to 32 weeks after challenge, t he stomach was removed from each animal for quantitative culture, urea se test, and histologic testing, and blood was collected for antibody determinations. No colonization occurred after greater than or equal t o 20 in vitro passages of wild-type strain G1.1 or with the ureA mutan t of G1.1. In contrast, infection occurred in animals challenged with wild-type G1.1 (99 of 101 animals) or the cagA (25 of 25) or vacA (25 of 29) mutant of G1.1. Infection with G1.1 persisted for at least 8 mo nths. All 15 animals challenged with any of three fresh human cagA-pos itive isolates became infected, in contrast to only 6 (23%) of 26 anim als challenged with one of four fresh human cagA-negative isolates (P < 0.001), Similar to infection in humans, H. pylori colonization of ge rbils induced gastric inflammation and a systemic antibody response to H, pylori antigens. These data confirm the utility of gerbils as an a nimal model of H, pylori infection and indicate the importance of bact erial strain characteristics for successful infection.