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Enteric lesions in SCID mice infected with "Helicobacter typhlonicus," a novel urease-negative Helicobacter species
C L Franklin1, L K Riley, R S Livingston
1Department of Veterinary Pathobiology, University of Missouri, Columbia, USA.
Background And Purpose:
Several rodent helicobacters have been associated with 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 chain reaction (PCR) analysis, it has become clear that several as yet unidentified Helicobacter species may also colonize rodents, but their capacity to cause disease is unknown.
Methods:
A Helicobacter species isolated from feces of a BALB/c mouse and provisionally 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" developed moderate to severe proliferative typhlocolitis, similar to that seen in SCID mice infected with H. hepaticus or H. bilis. However, in contrast to mice infected with H. hepaticus or H. bilis, lesions of chronic active hepatitis were not detected in mice inoculated with "H. typhlonicus." A similar disease syndrome developed in SCID mice cohabitated with B6D2F1 mice naturally infected with a novel Helicobacter species that was genetically identical to "H. typhlonicus."
Conclusion:
"Helicobacter typhlonicus" joins a growing list of helicobacters that are capable of inducing enteric disease in immunodeficient mice.
Insights
Helicobacter typhlonicus causes enteric disease in immunodeficient mice, similar to other Helicobacter species. This finding expands the list of known Helicobacter-induced enteric pathogens in susceptible rodent models.
Area of Science:
- Veterinary Pathology
- Microbiology
- Immunology
Background:
- Several Helicobacter species are linked to chronic active hepatitis and inflammatory bowel disease in rodents.
- Severe combined immunodeficient (SCID) mice are susceptible to diseases caused by emerging Helicobacter pathogens.
- Unidentified Helicobacter species in rodents may cause disease, but their pathogenic potential is largely unknown.
Purpose of the Study:
- To investigate the pathogenic potential of a novel Helicobacter species, provisionally named "H. typhlonicus", isolated from mouse feces.
- To determine if "H. typhlonicus" can induce disease in immunodeficient mice.
Main Methods:
- Four-week-old helicobacter-free SCID mice (n=22) were inoculated with "H. typhlonicus".
- Mice were monitored, and liver and intestinal tissues were collected at various time points post-inoculation.
- Histologic examination and polymerase chain reaction (PCR) analyses were performed on collected specimens.
Main Results:
- SCID mice inoculated with "H. typhlonicus" developed moderate to severe proliferative typhlocolitis.
- Lesions were similar to those observed in SCID mice infected with H. hepaticus or H. bilis.
- Chronic active hepatitis lesions were not observed in mice infected with "H. typhlonicus".
Conclusions:
- "Helicobacter typhlonicus" is capable of inducing enteric disease in immunodeficient mice.
- This bacterium expands the known spectrum of Helicobacter-induced enteric diseases in susceptible hosts.
- The findings highlight the importance of identifying novel Helicobacter species and understanding their pathogenic roles.