How Legionella subverts the cell

Of the 35 species of Legionella bacteria, one is implicated in most outbreaks of Legionnaires’ disease, a severe pneumonia. Now researchers at Yale have revealed how that bacterium, L. pneumophila, subverts the normal functions of cells in order to replicate.

During infection the bacterium travels to the lungs and invades alveolar macrophages, white blood cells which normally hunt down and destroy bacteria. L. pneumophila injects a protein into the macrophage that thwarts its transport to lysosomes, where the bacterium would be destroyed. Instead, the bacterium moves to the nutrient-rich endoplasmic reticulum, where it replicates. “These results show that the Legionella bacteria have the ability to inject a bacterial protein directly into macrophages during infection,” said Craig R. Roy, Ph.D., associate professor of microbial pathogenesis. The results were published in the January 25 issue of Science.