Pathogenesis of Campylobacter spp. in athymic and euthymic germfree mice

Adult athymic (nu/nu) and euthymic (+/nu) germfree BALB/c mice were orally challenged with pure cultures of Campylobacter jejuni (human clinical fecal strains) and a human blood isolate of Campylobacter fetus subsp. fetus. After a period of adaptation to the mouse intestinal tract, all three C. jejuni strains caused disease in gnotobiotic mice. Mouse-adapted, weakly cytotoxic C. jejuni 45100 consistently induced disease symptoms (transient diarrhea, cecal shrinkage, and acute inflammatory changes with eosinophilia in the lower intestinal mucosa) in nu/nu mice 7 to 9 days after oral challenges. Conversely, no overt disease or histopathology was evident in +/nu mice challenged with the same strain (45100). After periods of adaptation in the murine alimentary tract, the two C. jejuni strains, 24 and INN 73-83, with greater cytotoxin-producing capacities, decreased cecal size and caused minor mucosal inflammatory changes in both nu/nu and +/nu BALB/c mice 1 to 2 weeks after intestinal colonization. A transient splenomegaly was also evident at 1 to 2 weeks after germfree nu/nu mice were colonized with each of the three C. jejuni strains used in this study. Occult blood was observed in a small percentage (approximately 11%) of nu/nu and +/nu BALB/c mice that were colonized with C. jejuni strains 45100 and INN 73-83. C. fetus subsp. fetus 255 colonized the alimentary tract of gnotobiotic mice, but neither morbidity nor mortality was evident. The disease we observed in the gnotobiotic mice, along with the histological changes in the intestinal tract after oral challenges, resembles symptoms of campylobacteriosis in humans. The gnotobiotic BALB/c mouse model of Campylobacter disease provides a unique opportunity to detail basic aspects of the acute and chronic pathogenesis of and immunity to this recently recognized disease.