JoVE Encyclopedia of Experiments
Microbiology
0 views • 2:30 min • August 29th, 2025
Begin with a multi-well plate containing pre-treated macrophages exposed to bacterial Legionella pneumophila outer membrane vesicles, or OMVs.
Add Legionella pneumophila at a defined bacterium-to-host cell ratio to infect the OMV-treated macrophages.
During incubation, the macrophages internalize the bacteria within membrane-bound phagosomes.
OMV pre-treatment alters macrophage signaling, inhibiting phagosome maturation.
This facilitates the formation of a Legionella-containing vacuole, which protects the bacteria and allows intracellular replication.
Add a detergent and incubate to lyse the macrophages. This releases the intracellular bacteria into the medium.
Streak the diluted lysate onto a nutrient-enriched agar plate.
During incubation, the bacteria grow and form visible colonies.
Count the colonies to determine the colony-forming units, or CFUs, representing the number of viable bacteria.
Compare the CFU counts between OMV-treated and untreated macrophages.
A higher CFU in OMV-treated compared to untreated macrophages indicates that OMVs facilitate Legionella survival within the macrophages.
To infect pre-treated or untreated THP-1 cells with wild-type L.pneumophila strain core B or mur
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