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Infection of Acanthamoeba castellanii by Chlamydia pneumoniae
A Essig1, M Heinemann, U Simnacher
1Department of Medical Microbiology and Hygiene, University of Ulm, Germany.
Abstract:
Chlamydia pneumoniae is an intracellular respiratory pathogen, which, similar to Legionella, might have developed mechanisms to escape the intracellular bactericidal activity of both human host cells and amoeba. We therefore investigated the intracellular growth and survival of C. pneumoniae in Acanthamoeba castellanii by using cell culture, immunofluorescence microscopy, and electron microscopy. A castellanii was incubated with purified elementary bodies of C. pneumoniae TW 183 at a concentration of 10(6) inclusion-forming units (IFU)/ml to give a ratio of approximately 1 IFU of C. pneumoniae per amoeba. Quantitative determination of chlamydial growth within A. castellanii revealed viable and infective C. pneumoniae in the range of 10(4) to 10(5) IFU/ml between days 7 and 14 postinfection. Immunofluorescence analysis and transmission electron microscopy with subsequent immunogold staining confirmed evidence of infection of the amoebae by C. Pneumoniae and additionally revealed that C. pneumoniae entered the typical growth cycle. Our results show that amoebae allow the survival of C. pneumoniae, suggesting that amoebae may serve as an additional reservoir for Chlamydia or Chlamydia-related organisms.
Insights
Acanthamoeba castellanii hosts Chlamydia pneumoniae, an intracellular respiratory pathogen. This study shows amoebae support C. pneumoniae survival and growth, suggesting a potential environmental reservoir for this bacteria.
Area of Science:
- Microbiology
- Cell Biology
- Pathogen Survival
Background:
- Chlamydia pneumoniae is an intracellular respiratory pathogen.
- It may possess mechanisms to evade host cell defenses, similar to Legionella.
- Its survival within protozoa like Acanthamoeba is not well understood.
Purpose of the Study:
- To investigate the intracellular growth and survival of Chlamydia pneumoniae within Acanthamoeba castellanii.
- To determine if amoebae can support the lifecycle of C. pneumoniae.
Main Methods:
- Cell culture of A. castellanii infected with C. pneumoniae elementary bodies.
- Immunofluorescence microscopy to detect C. pneumoniae.
- Transmission electron microscopy with immunogold staining for ultrastructural analysis.
Main Results:
- Viable and infective C. pneumoniae (10^4 to 10^5 IFU/ml) were detected in A. castellanii between 7 and 14 days post-infection.
- Immunofluorescence and electron microscopy confirmed C. pneumoniae infection and typical intracellular growth cycle within amoebae.
- A. castellanii supported the survival and replication of C. pneumoniae.
Conclusions:
- Acanthamoeba castellanii serves as a host for Chlamydia pneumoniae.
- Amoebae may act as an environmental reservoir for C. pneumoniae or related organisms.
- This interaction highlights potential transmission routes and survival strategies for intracellular bacteria.