Enteric lesions in SCID mice infected with "Helicobacter typhlonicus," a novel urease-negative Helicobacter species

Background and Purpose: Several rodent helicobacters have been associated w ith chronic active hepatitis or inflammatory bowel disease. Severe combined immunodeficient (SCID) mice appear to be inherently susceptible to disease attributable to these emerging pathogens. With the advent of polymerase ch ain reaction (PCR) analysis, it has become clear that several as yet uniden tified Helicobacter species may also colonize rodents, but their capacity t o cause disease is unknown. Methods: A Helicobacter species isolated from feces of a BALB/c mouse and p rovisionally named "H, typhlonicus" was used to inoculate helicobacter-free 4-week-old SCID mice (n = 11 males and 11 females). At various weeks after inoculation, mice were sacrificed and liver and intestinal specimens were collected for histologic examination and PCR analyses. Results: The C.B-17 scid/scid mice inoculated with "H, typhlonicus" develop ed moderate to severe proliferative typhlocolitis, similar to that seen in SCID mice infected with H, hepaticus or H, bills, However, in contrast to m ice infected with H, hepaticus or H, bills, lesions of chronic active hepat itis were not detected in mice inoculated with "H, typhlonicus." A similar disease syndrome developed in SCID mice cohabitated with B6D2F1 mice natura lly infected with a novel Helicobacter species that was genetically identic al to "H. typhlonicus," Conclusion: "Helicobacter typhlonicus" joins a growing list of helicobacter s that are capable of inducing enteric disease in immunodeficient mice.