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Comparative analysis of clinics, pathologies and immune responses in BALB/c and C57BL/6 mice infected with
Juliane Fornefett1, Jaqueline Krause2, Kristin Klose3
1Institute for Bacteriology and Mycology, Faculty of Veterinary Medicine, University Leipzig, Leipzig, Germany.
Abstract:
Streptobacillus (S.) moniliformis is a rat-associated zoonotic pathogen that occasionally causes disease in other species. We investigated the working hypothesis that intranasal infection might lead to different immune responses in C57BL/6 and BALB/c mice associated with distinct pathologies. This study confirmed with 75% mortality the known high susceptibility of C57BL/6 mice to Streptobacillus moniliformis infection in comparison to BALB/c mice which did not develop signs of disease. Main pathologies in C57BL/6 mice were purulent to necrotizing lymphadenitis and pneumonia. Significant seroconversion was recorded in surviving mice of both strains. Differentiation of IgG-subclasses revealed mean ratios of IgG2b to IgG1 below 0.5 in sera of all mice prior to infection and of BALB/c mice post infection. In contrast, C57BL/6 mice had a mean IgG2b/IgG1 ratio of 2.5 post infection indicating a Th1 immune response in C57BL/6 versus a Th2 response in BALB/c mice. Evaluation of different sentinel systems revealed that cultural and serological investigations of these animals might not be sufficient to detect infection. In summary, an intranasal S. moniliformis infection model in C57BL/6 mice leading to purulent to necrotizing inflammations in the lung, the lymph nodes and other organs associated with a Th1 immune response is described.
Insights
Streptobacillus moniliformis intranasal infection causes high mortality and severe pathology in C57BL/6 mice, inducing a Th1 immune response. BALB/c mice showed resistance and a Th2 response, indicating strain-specific susceptibility and immune reactions.
Area of Science:
- Immunology
- Microbiology
- Pathology
Background:
- Streptobacillus moniliformis is a zoonotic pathogen associated with rats.
- Intranasal infection models are crucial for studying respiratory pathogens.
- Mouse strains exhibit differential susceptibility to infections.
Purpose of the Study:
- To investigate the immune response and pathology following intranasal Streptobacillus moniliformis infection in C57BL/6 and BALB/c mice.
- To compare the susceptibility and distinct pathologies induced by S. moniliformis in different mouse strains.
- To characterize the immune response, specifically Th1 vs. Th2, in susceptible and resistant mouse models.
Main Methods:
- Intranasal inoculation of Streptobacillus moniliformis in C57BL/6 and BALB/c mice.
- Assessment of mortality rates and clinical signs.
- Histopathological examination of affected tissues (lymph nodes, lungs).
- Serological analysis including IgG subclass differentiation (IgG2b/IgG1 ratio).
Main Results:
- C57BL/6 mice exhibited high susceptibility (75% mortality) with severe purulent lymphadenitis and pneumonia.
- BALB/c mice showed resistance, with no signs of disease.
- Significant seroconversion occurred in surviving mice of both strains.
- C57BL/6 mice displayed a Th1 immune response (IgG2b/IgG1 ratio of 2.5), while BALB/c mice showed a Th2 response (ratio < 0.5).
- Standard sentinel systems may be insufficient for infection detection.
Conclusions:
- Intranasal S. moniliformis infection elicits strain-dependent pathologies and immune responses in mice.
- C57BL/6 mice serve as a valuable model for studying S. moniliformis-induced Th1-mediated pathology.
- BALB/c mice are resistant, exhibiting a Th2-biased response.
- Diagnostic limitations highlight the need for comprehensive monitoring strategies.