Drosophila melanogaster S2 cells: a model system to study Chlamydia interaction with host cells

Area of Science:

• Microbiology
• Cell Biology
• Genetics

Background:

• Chlamydia spp. cause significant human diseases, but studying host-pathogen interactions is challenging due to limited bacterial genetics and difficulties in mammalian genetic screens.
• RNA interference (RNAi) in tractable model hosts like Drosophila melanogaster offers a novel method for host gene inactivation and identifying pathogenesis factors.

Purpose of the Study:

• To evaluate if Chlamydia trachomatis infection of Drosophila melanogaster S2 cells recapitulates key aspects of mammalian cell infections.
• To establish Drosophila S2 cells as a model system for dissecting host factors in Chlamydia pathogenesis.

Main Methods:

• Infection of Drosophila melanogaster S2 cells with Chlamydia trachomatis.
• Assessment of Chlamydia entry, inclusion formation, lipid acquisition, phagolysosomal avoidance, and differentiation.
• Utilizing RNA interference (RNAi) to inactivate host genes, specifically Rac.

Main Results:

• Chlamydia entry into S2 cells was inhibited by heparin and cytochalasin D, similar to mammalian cells.
• Inclusions formed in S2 cells, acquired Golgi-derived sphingolipids, and avoided phagolysosomal fusion.
• Elementary body (EB) to reticulate body (RB) differentiation occurred, but RB to EB development and host cell killing were not observed.
• RNAi-mediated inactivation of Rac significantly inhibited Chlamydia infection in S2 cells.

Conclusions:

• Drosophila S2 cells provide a valid model system that faithfully mimics early Chlamydia host cell interactions.
• This system is suitable for systematically dissecting host functions essential for the pathogenesis of obligate intracellular pathogens like Chlamydia.