Persistent Helicobacter pullorum colonization in C57BL/6NTac mice: a new mouse model for an emerging zoonosis.

Helicobacter pullorum, an enterohepatic Helicobacter species, is associated with gastroenteritis and hepatobiliary disease in humans and chickens. Recently, a novel H. pullorum outbreak in barrier-maintained rats and mice was described. In this study, persistence of infection and serological responses were further evaluated in H. pullorum-infected female C57BL/6NTac and C3H/HeNTac mice obtained from the barrier outbreak. C57BL/6NTac mice (n=36) aged 10-58 weeks were confirmed to be chronically infected with H. pullorum by PCR or culture of caecum, colon and faeces, with no evidence of hepatic infection; two of three C3H/HeNTac mice cleared H. pullorum infection by 26 weeks of age. A quantitative PCR (qPCR) assay based on the cdtB gene specific to H. pullorum demonstrated that colonization was high in the caecum and colon at 10(4)-10(6) c.f.u. equivalents per µg host DNA, and decreased by several logs from 32 to 58 weeks of age. Infected mice were seropositive by ELISA, and H. pullorum-specific IgG levels decreased as colonization was lost over time in selected mice. Consistent with the lack of pathology associated with chronic infection of C57BL/6 mice with other murine enteric helicobacters, C57BL/6NTac and C3H/HeNTac mice infected with H. pullorum did not develop gross or histological lesions of the liver or gastrointestinal tract. The cdtB-based qPCR assay can be used in screening animals, food sources and environmental samples for H. pullorum, as this food-borne pathogen has zoonotic potential. These findings will also allow future studies in murine models to dissect potential pathogenic mechanisms for this emerging pathogen.