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Updated: Sep 27, 2026
Tractable Mammalian Cell Infections with Protozoan-primed Bacteria
Published on: April 2, 2013
[Models for the study of the toxic action of Legionella pneumophila]
Abstract:
L. pneumophila virulent culture and the filtrate of this culture disintegrated with ultrasound were shown to be toxic for guinea-pig peritoneal macrophages in vitro and for AKR mice. The virulent culture of this infective agent and the filtrate of the supernatant fluid obtained from the washings of its virulent culture had no toxic effect on a macrophage monolayer culture and on mice. The use of these models for characterizing Legionella intracellular toxic activity, as well as for characterizing Legionella strains isolated from patients and the environment, is proposed.
Insights
Legionella pneumophila (L. pneumophila) virulent cultures and their sonicates are toxic to macrophages and mice. Non-sonicated virulent cultures and filtrates showed no toxicity, suggesting a role for intracellular toxins.
Area of Science:
- Microbiology
- Immunology
- Toxicology
Background:
- Legionella pneumophila (L. pneumophila) is an intracellular bacterium responsible for Legionnaires' disease.
- Understanding the toxic mechanisms of L. pneumophila is crucial for developing effective treatments.
- Previous studies have focused on extracellular virulence factors, but intracellular toxicity requires further investigation.
Purpose of the Study:
- To investigate the toxic effects of L. pneumophila virulent cultures and their components on host cells and animal models.
- To differentiate the toxicity of sonicated versus non-sonicated virulent cultures and their filtrates.
- To propose models for characterizing L. pneumophila's intracellular toxic activity and strain virulence.
Main Methods:
- Exposure of guinea-pig peritoneal macrophages and AKR mice to virulent L. pneumophila cultures.
- Treatment with ultrasound-disintegrated virulent cultures and their filtrates.
- Assessment of toxicity in vitro (macrophage monolayer culture) and in vivo (mice).
Main Results:
- Ultrasound-disintegrated virulent L. pneumophila cultures and their filtrates demonstrated toxicity towards macrophages and mice.
- Non-sonicated virulent cultures and filtrates of supernatant fluid from washings showed no toxic effects.
- These findings suggest that intracellular components released by sonication are responsible for the observed toxicity.
Conclusions:
- The toxicity of L. pneumophila is associated with intracellular components released upon cell disintegration.
- Proposed models using macrophages and mice can effectively characterize the intracellular toxic activity of L. pneumophila.
- These models can aid in differentiating virulent and avirulent strains of L. pneumophila from clinical and environmental sources.
