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Persistence of Rickettsia prowazekii in cotton rat macrophage cultures
N G Kekcheeva1, I N Kokorin, V L Popov
1N.F. Gamaleya Research Institute of Epidemiology and Microbiology, AMS USSR, Moscow.
Abstract:
Rickettsia prowazekii is able to multiply and persist for a long time in cotton rat macrophage culture (29-days observation period). Electron microscopic studies showed that the structure of Rickettsiae remained intact at different intervals post-inoculation (p.i.). In the course of persistence Rickettsiae revealed a reduced capacity to infect chick embryos and guinea pigs, however, the infectious agent could be isolated at all stages of persistence of cultured cells such as fibroblasts of the guinea pig embryo, macrophages of intact cotton rats.
Insights
Rickettsia prowazekii persists in cotton rat macrophages for 29 days, maintaining structural integrity. While infectivity decreases, the bacteria remain isolatable from host cells.
Area of Science:
- Microbiology
- Cell Biology
- Infectious Diseases
Background:
- Rickettsia prowazekii is an obligate intracellular bacterium responsible for epidemic typhus.
- Understanding the long-term survival mechanisms of Rickettsia in host cells is crucial for disease control.
Purpose of the Study:
- To investigate the persistence of Rickettsia prowazekii in cotton rat macrophage cultures.
- To evaluate the structural integrity and infectivity of Rickettsia prowazekii during prolonged in vitro culture.
Main Methods:
- Culturing of Rickettsia prowazekii in cotton rat macrophage cell cultures for 29 days.
- Electron microscopy to assess bacterial structural integrity at various post-inoculation intervals.
- Infectivity assays using chick embryos and guinea pigs, and isolation from cultured host cells.
Main Results:
- Rickettsia prowazekii successfully multiplied and persisted in cotton rat macrophages for up to 29 days.
- Electron microscopy confirmed the intact structure of Rickettsiae throughout the observation period.
- Persistent Rickettsiae exhibited reduced infectivity for chick embryos and guinea pigs but remained recoverable from guinea pig embryo fibroblasts and cotton rat macrophages.
Conclusions:
- Cotton rat macrophages provide a suitable environment for long-term Rickettsia prowazekii survival.
- Rickettsia prowazekii maintains structural integrity during prolonged intracellular persistence.
- Reduced infectivity during persistence may represent an adaptive survival strategy, with the bacteria remaining viable for potential re-emergence.
