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Growth of Francisella spp. in rodent macrophages
L D Anthony1, R D Burke, F E Nano
1Department of Biochemistry, University of Victoria, British Columbia, Canada.
Abstract:
We examined the nature of the interactions between the facultative intracellular pathogens Francisella tularensis and F. novicida and rodent macrophages. Growth of F. tularensis LVS was observed in macrophage monolayers from mice, guinea pigs, or rats. In contrast, F. novicida grew in macrophages from mice and guinea pigs but not in macrophages from rats. Transmission electron microscopy studies indicated that both Francisella species survive within macrophage phagosomes that are unfused with lysosomes.
Insights
Francisella tularensis and Francisella novicida are facultative intracellular pathogens. These bacteria survive within macrophage phagosomes, but F. novicida exhibits species-specific growth differences in rodent macrophages.
Area of Science:
- Microbiology
- Immunology
- Pathogen-host interactions
Background:
- Facultative intracellular pathogens like Francisella species pose significant challenges in infectious disease research.
- Understanding their interactions with host immune cells, particularly macrophages, is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the interactions between Francisella tularensis and Francisella novicida and rodent macrophages.
- To determine the intracellular survival mechanisms and host-specific growth patterns of these pathogens.
Main Methods:
- Culturing of Francisella tularensis LVS and F. novicida in macrophage monolayers from various rodent species (mice, guinea pigs, rats).
- Utilizing transmission electron microscopy to visualize pathogen location within host cells.
Main Results:
- Francisella tularensis LVS demonstrated growth in macrophages from mice, guinea pigs, and rats.
- Francisella novicida grew in mouse and guinea pig macrophages but not in rat macrophages.
- Both species were observed to survive within macrophage phagosomes that did not fuse with lysosomes.
Conclusions:
- Rodent macrophages provide a suitable environment for Francisella species, with variations in growth depending on the host species and bacterial strain.
- The ability of Francisella species to evade lysosomal fusion is a key factor in their intracellular survival within macrophages.