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Specific vs. nonspecific immune responses in murine respiratory mycoplasmosis
J W Simecka1, J K Davis, G H Cassell
1Department of Microbiology, University of Alabama at Birmingham 35294.
Abstract:
Murine respiratory mycoplasmosis (MRM), due to Mycoplasma pulmonis, is a chronic respiratory disease in laboratory rats. LEW and F344 rats differ in the severity and progression of disease. LEW rats develop more severe disease than do F344 rats. Also, F344 rats are able to resolve lung and middle ear lesions, but the severity of these lesions in LEW rats continues to increase. LEW lymphocytes produce higher responses in vitro to various mitogens, including M. pulmonis mitogen, than do F344 lymphocytes; this difference is apparently due to higher levels of T-helper cells in LEW rats. The level of infiltration or expansion of mononuclear cells in the submucosa probably depends upon the host's ability to respond to nonspecific stimuli. In contrast to nonspecific responses, F344 rats produce a much higher specific antibody and cellular response to M. pulmonis antigens after immunization, suggesting that F344 rats, in contrast to LEW rats, are able to resolve lesions because they are able to mount an effective immune response to M. pulmonis.
Insights
Laboratory rats (Rattus norvegicus) exhibit varying susceptibility to Mycoplasma pulmonis. F344 rats resolve Mycoplasma pulmonis infections better than LEW rats due to a more effective immune response.
Area of Science:
- Immunology
- Infectious Diseases
- Animal Models
Background:
- Murine respiratory mycoplasmosis (MRM) is a chronic respiratory disease in laboratory rats caused by Mycoplasma pulmonis.
- LEW and F344 rat strains exhibit differential susceptibility and disease progression to MRM.
- LEW rats develop more severe disease and persistent lesions compared to F344 rats, which can resolve lung and middle ear lesions.
Purpose of the Study:
- To investigate the immunological differences between LEW and F344 rats in response to Mycoplasma pulmonis infection.
- To understand the mechanisms underlying the differential resolution of lesions in these rat strains.
Main Methods:
- Comparative analysis of in vitro lymphocyte responses to mitogens and Mycoplasma pulmonis antigens.
- Assessment of in vivo antibody and cellular immune responses to Mycoplasma pulmonis antigens after immunization.
- Histopathological evaluation of lung and middle ear lesions.
Main Results:
- LEW lymphocytes show higher in vitro responses to mitogens, including Mycoplasma pulmonis mitogen, attributed to increased T-helper cells.
- F344 rats exhibit significantly higher specific antibody and cellular responses to Mycoplasma pulmonis antigens post-immunization compared to LEW rats.
- F344 rats demonstrate the ability to resolve lung and middle ear lesions, while LEW rats show progressive lesion severity.
Conclusions:
- The ability of F344 rats to resolve Mycoplasma pulmonis-induced lesions is linked to their capacity to mount an effective specific immune response.
- Differential immune responses, particularly the specific adaptive immunity to Mycoplasma pulmonis, dictate the outcome of murine respiratory mycoplasmosis in LEW and F344 rats.