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Experimental infection of Chlamydia pneumoniae in mice
S S Kaukoranta-Tolvanen1, A L Laurila, P Saikku
1Department of Virology, University of Helsinki, Finland.
Abstract:
NIH/S, Swiss Webster, and BALB/c mice were infected intranasally with three Chlamydia pneumoniae isolates, Kajaani 6, Helsinki 12, and TW-183. C. pneumoniae could be isolated from the lung homogenates and bronchoalveolar lavage fluids up to the third week post-infection. Specific serum IgG antibodies against C. pneumoniae reached high levels in the third week and remained elevated until the end of the 6-week follow-up period. Serum IgM levels were highest in the third week post-infection and started to decrease thereafter. In spite of these signs of ongoing infection, the mice did not show any symptoms of disease. NIH/S mice could be readily and uniformly infected, while BALB/c mice were the most resistant and developed the weakest antibody response. The greatest histological changes were detected in NIH/S mice as well. The inflammatory infiltrate, which consisted of lymphocytes and plasma cells throughout the study, was restricted to the peribronchial and perivascular space and to the interstitium of the lung parenchyma.
Insights
Mice infected with Chlamydia pneumoniae showed signs of infection but no disease symptoms. NIH/S mice were most susceptible, exhibiting stronger immune responses and lung inflammation compared to BALB/c mice.
Area of Science:
- Microbiology
- Immunology
- Pathology
Background:
- Chlamydia pneumoniae is a significant respiratory pathogen.
- Understanding host-pathogen interactions is crucial for developing effective treatments.
- Murine models are essential for studying Chlamydia pneumoniae infections.
Purpose of the Study:
- To investigate the course of Chlamydia pneumoniae infection in different mouse strains.
- To evaluate the immune response and pathological changes in infected mice.
- To compare the susceptibility of NIH/S, Swiss Webster, and BALB/c mice to C. pneumoniae.
Main Methods:
- Intranasal inoculation of mice with three C. pneumoniae isolates.
- Bacteriological cultures of lung homogenates and bronchoalveolar lavage fluid.
- Measurement of serum IgG and IgM antibody levels.
- Histopathological examination of lung tissues.
Main Results:
- C. pneumoniae was isolated from lungs and lavage fluid up to 3 weeks post-infection.
- Elevated serum IgG antibodies were detected throughout the 6-week study.
- NIH/S mice showed higher susceptibility, stronger antibody responses, and greater lung inflammation compared to BALB/c mice.
- Despite infection, mice remained asymptomatic.
Conclusions:
- NIH/S mice provide a suitable model for studying C. pneumoniae infection due to their susceptibility and robust immune response.
- BALB/c mice exhibit resistance to C. pneumoniae infection.
- The study highlights the asymptomatic nature of C. pneumoniae infection in this murine model, despite evidence of ongoing infection and inflammation.