Mitigation of Expression of Virulence Genes in Internalized in the Free-Living Amoeba C2c Maky.

is a human pathogen responsible for a severe form of pneumonia named Legionnaire disease. Its natural habitat is aquatic environments, being in a free state or intracellular parasites of free-living amoebae, such as . This pathogen is able to replicate within some amoebae. C2c Maky, a non-pathogenic amoeba, was previously demonstrated to resist to and even to be able to eliminate the strains Philadelphia, Lens, and Paris. Here, we studied the induction of seven virulence genes of three strains (Paris, Philadelphia, and Lens) within C2c Maky in comparison within and with the gene expression level of strains alone used as controls. We defined a gene expression-based virulence index to compare easily and without bias the transcript levels in different conditions and demonstrated that C2c Maky did not increase the virulence of strains in contrast to . These results confirmed the non-permissiveness of C2c Maky toward strains.