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Susceptibility of germ-free mice to infectious megaenteron
Abstract:
Germ-free (GF)-ICR mice were shown to be less susceptible to oral inoculation with a pathogenic strain of Escherichia coli (E. coli 0115a, c: K(B) than GF-CF No.1 mice. In GF-CF No. 1 mice a large number of organisms were recovered from the intestinal wall from the cecum to the rectum 3 to 7 days after inoculation. Unlike those in GF-CF No. 1 mice, lesions in GF-ICR mice were localized in a part of the cecum and organisms were recovered only from the cecal wall and rarely from organs other than those of the alimentary tract. In both strains of mice, however, organisms were recovered in large number from the intestinal contents. Histopathology and immunofluorescence revealed organisms closely attached to the surface of the cecum, colon and rectal epithelia in GF-CF No. 1 mice but only in a part of the cecal epithelium in GF=ICR mice. After being in contact with conventional CF No. 1 mice for 21 days and then inoculated orally with the pathogenic E. coli, ex GF-CF No. 1 mice died within 14 days with severe intestinal lesions, but ex-GF-ICR mice survived without lesions.
Insights
Germ-free mice exhibit varying susceptibility to pathogenic Escherichia coli (E. coli). GF-ICR mice show greater resistance than GF-CF No. 1 mice, with localized lesions and reduced bacterial colonization.
Area of Science:
- Microbiology
- Immunology
- Gastroenterology
Background:
- Germ-free (GF) animal models are crucial for understanding host-microbe interactions.
- Pathogenic Escherichia coli (E. coli) can cause significant intestinal disease.
- Strain-specific differences in susceptibility to enteric pathogens are not fully understood.
Purpose of the Study:
- To compare the susceptibility of two different germ-free mouse strains (GF-ICR and GF-CF No. 1) to oral inoculation with a pathogenic E. coli strain.
- To investigate the colonization patterns and lesion development in response to E. coli infection in GF mice.
- To assess the impact of prior conventionalization on E. coli susceptibility.
Main Methods:
- Oral inoculation of germ-free ICR and CF No. 1 mice with pathogenic E. coli (0115a, c: K(B)).
- Bacterial recovery from intestinal contents and walls at various time points post-inoculation.
- Histopathological examination and immunofluorescence staining to assess lesions and bacterial attachment.
- Conventionalization of ex-GF mice with conventional CF No. 1 mice before E. coli challenge.
Main Results:
- GF-ICR mice were less susceptible to E. coli than GF-CF No. 1 mice.
- GF-CF No. 1 mice showed extensive bacterial colonization from cecum to rectum and severe lesions.
- GF-ICR mice exhibited localized cecal lesions with limited bacterial spread.
- Ex-GF-CF No. 1 mice died from severe intestinal lesions after E. coli challenge, while ex-GF-ICR mice survived.
Conclusions:
- Mouse strain significantly influences susceptibility to pathogenic E. coli colonization and disease.
- GF-CF No. 1 mice are highly susceptible, developing widespread intestinal pathology.
- GF-ICR mice demonstrate a degree of resistance, with localized disease.
- Prior exposure to a conventional microbiota may confer protection against E. coli-induced intestinal damage.