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Relationship of hydrogen peroxide production by Mycoplasma pulmonis to virulence for catalase-deficient mice
Abstract:
Mycoplasma pulmonis, an etiological agent of murine pneumonia, produced about 0.065 mumoles of hydrogen peroxide (H(2)O(2)) per hr per 10(10) colony-forming units. When glucose was present at a concentration of 0.01 m, H(2)O(2) production was increased by 50%. To determine if H(2)O(2) production by M. pulmonis could be correlated with virulence, normal, acatalasemic, and acatalatic mice were infected with the organism. Three days after infection with M. pulmonis significantly more acatalatic mice had pneumonia than did normal or acatalasemic mice. The pneumonia in acatalatic mice was also more severe than in the other two groups. Five days after infection, pneumonia in the acatalatic mice was resolved, whereas normal mice were severely affected. The presence of pneumonia and the severity were correlated with the recovery of M. pulmonis from the lesions. In vitro studies of the effect of catalase on M. pulmonis showed that exogenously supplied catalase stimulated the growth of M. pulmonis at 37 C and prolonged its survival at 25 C. Hemolysis of sheep blood, guinea pig blood, rabbit blood, and normal and acatalasemic mouse blood by M. pulmonis was inversely related to the catalase activity of the erythrocytes. These findings suggest that H(2)O(2) secretion contributes to the virulence of M. pulmonis and to the death of the microorganism in the absence of host catalase.
Insights
Mycoplasma pulmonis produces hydrogen peroxide (H2O2), a key factor in its virulence. Host catalase levels significantly impact M. pulmonis infection severity and pathogen survival.
Area of Science:
- Microbiology
- Pathogenesis
- Biochemistry
Background:
- Mycoplasma pulmonis is a primary cause of pneumonia in mice.
- Hydrogen peroxide (H2O2) production by microorganisms can influence disease processes.
- Catalase is an enzyme that neutralizes H2O2.
Purpose of the Study:
- To investigate the role of H2O2 production by M. pulmonis in murine pneumonia.
- To correlate H2O2 production with the virulence of M. pulmonis.
- To examine the effect of host catalase on M. pulmonis infection and survival.
Main Methods:
- Quantifying H2O2 production by M. pulmonis in vitro, with and without glucose.
- Infecting normal, acatalasemic, and acatalatic mice with M. pulmonis and assessing pneumonia severity.
- Evaluating the effect of exogenous catalase on M. pulmonis growth and survival in vitro.
- Assessing the hemolytic activity of M. pulmonis against erythrocytes with varying catalase levels.
Main Results:
- M. pulmonis produced H2O2, with increased production observed in the presence of glucose.
- Acatalatic mice exhibited more severe pneumonia and higher M. pulmonis recovery rates from lesions compared to normal or acatalasemic mice.
- Exogenous catalase enhanced M. pulmonis growth and survival, while hemolytic activity was inversely related to erythrocyte catalase levels.
Conclusions:
- H2O2 secretion by M. pulmonis contributes to its virulence in murine pneumonia.
- Host catalase activity plays a protective role against M. pulmonis infection.
- The findings suggest a mechanism for M. pulmonis survival and pathogenesis influenced by host catalase.