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Published on: September 9, 2014
Infection of Cultured Mouse Macrophages with Shigella flexneri
1Department of Epidemiology and Microbiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania 15213.
Abstract:
Virulent, avirulent, and attenuated hybrid strains of Shigella flexneri 2a are equally susceptible to phagocytosis by cultured mouse peritoneal macrophages. The virulent strain is highly lethal for the macrophages, whereas the avirulent is not and is killed. The attenuated hybrid strain is intermediate in its lethality. Comparable results were obtained by using virulent and avirulent S. flexneri 1b, 3, and 5. Destruction of macrophages occurs shortly after infection, suggesting virulent strains may possess a toxic component. The relationship of the ability to kill macrophages with multiplication of virulent shigellae in mucosal tissue is discussed.
Insights
Virulent Shigella flexneri strains kill macrophages after phagocytosis, while avirulent strains are killed by them. Attenuated strains show intermediate lethality, suggesting a toxic component in virulent bacteria.
Area of Science:
- Microbiology
- Immunology
- Bacterial Pathogenesis
Background:
- Shigella flexneri causes bacillary dysentery.
- Macrophage phagocytosis is a key immune defense mechanism.
- Understanding bacterial virulence factors is crucial for disease control.
Purpose of the Study:
- To investigate the interaction between different Shigella flexneri strains and mouse peritoneal macrophages.
- To determine if bacterial virulence correlates with macrophage lethality.
- To explore potential toxic components in virulent Shigella strains.
Main Methods:
- Cultured mouse peritoneal macrophages were exposed to virulent, avirulent, and attenuated Shigella flexneri 2a hybrid strains.
- Macrophage viability and bacterial survival were assessed post-infection.
- Comparable experiments were conducted with other Shigella flexneri serotypes (1b, 3, and 5).
Main Results:
- All Shigella flexneri strains, regardless of virulence, were equally susceptible to phagocytosis.
- Virulent strains were lethal to macrophages, while avirulent strains were killed by macrophages.
- Attenuated strains exhibited intermediate lethality.
- Macrophage destruction occurred rapidly after infection with virulent strains.
Conclusions:
- Virulent Shigella flexneri strains possess a component toxic to macrophages.
- Macrophage lethality by virulent strains may be linked to their ability to multiply in host tissues.
- This study highlights differential host-pathogen interactions based on bacterial virulence.
