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Interactions of TRIC agents with macrophages and BHK-21 cells observed by electron microscopy
Abstract:
TRIC agents do not multiply in mouse peritoneal macrophages in culture but have a toxic effect on them, whereas they multiply readily in BHK-21 cells. Sections of macrophages and of BHK-21 cells fixed during the first 90 min after inoculation were examined by electron microscopy. Macrophages ingested all forms of the organism, which were eventually degraded in lysosomes. However, elementary bodies were distinguished from other TRIC particles by the delay in their transfer to lysosomes. BHK-21 cells ingested elementary bodies selectively, and in these cells the organisms were neither found in lysosomes nor degraded. Instead they showed morphological changes that probably represented an early stage of development.
Insights
TRIC agents are toxic to mouse macrophages but multiply in BHK-21 cells. Electron microscopy revealed macrophages degrade TRIC agents, while BHK-21 cells support their early development.
Area of Science:
- Microbiology
- Cell Biology
- Pathogen-Host Interactions
Background:
- TRIC agents, obligate intracellular bacteria, exhibit complex interactions with host cells.
- Understanding the initial stages of TRIC agent infection is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the differential interactions of TRIC agents with mouse peritoneal macrophages and BHK-21 cells.
- To elucidate the early cellular events following TRIC agent inoculation using electron microscopy.
Main Methods:
- Comparative cell culture of mouse peritoneal macrophages and BHK-21 cells.
- Inoculation with TRIC agents and fixation at 90 minutes post-inoculation.
- Ultrastructural analysis via electron microscopy.
Main Results:
- TRIC agents did not multiply in macrophages but were toxic, being degraded in lysosomes.
- Macrophages ingested all TRIC agent forms, with elementary bodies showing delayed lysosomal transfer.
- BHK-21 cells selectively ingested elementary bodies, which were not degraded and showed developmental changes.
Conclusions:
- Macrophages internalize and degrade TRIC agents, indicating an innate defense mechanism.
- BHK-21 cells provide a permissive environment for TRIC agent replication, supporting early developmental stages.
- Differential host cell permissiveness influences TRIC agent survival and development.