The team investigates the molecular pathogenesis of Legionella pneumophila, the causative agent of the severe pneumonia legionellosis. It is tightly related to the Centre National de Références des Légionelles (Lyon), and thus uses both basic research approaches and clinical microbiology to address the question about the emergence of virulence of this opportunistic pathogen. 
L. pneumophila is ubiquitous in the aquatic environment as well as in man-made systems, where it infects and replicates in protozoa. Co-evolution with amoeba has been proposed to result in the selection of virulence factors that enables Legionella to infect human alveolar macrophages. However, the molecular mechanisms controlling the bacterial intracellular cycle in its phagocytic host cells, environmental amoeba and human macrophages, remain to be elucidated to demonstrate this attractive hypothesis.
The team aims at addressing this question by focusing on three aspects of the Legionella/host cell interactions and molecular epidemiology, which are related with ECOFECT work packages WP1 and WP3:
   - WP1: protein-protein interactions between the 250 bacterial effectors of the Type 4 Secretion System, which plays a key role in virulence, and host cell proteins involved in vesicular trafficking, apoptosis or autophagy (Hervet et al. Infect. Immun. 2011 79(5):1936; Allombert et al. Microbes infect. 2013 15(14-15):981; Michard et al. Front Microbiol. 2015 10;6:87; Michard et al. Mbio 2015 5;6(3). pii: e00354-15).
   - WP1: the role of cyclic-di-GMP, a second bacterial messenger, in the control of bacterial virulence traits (Levet-Paulo et al. J. Biol. Chem. 2011; 286 (36):31136; Allombert et al. Infect. Immun. 2014 82(3):1222), and in the formation of biofilms which results in environmental reservoirs of  Legionella.
   - WP3: the role of amoebae in the emergence of Legionella virulence and the environmental persistence of Legionella. Studies are developed to improve our knowledge about the molecular basis of the relationship between amoeba, multidrug resistance and virulence of L. pneumophila (Ferhat et al. PLoS One 2009; 4(11):e7732 ; Atlan et al. Protist  2012 163(6): 888; Fuche et al. J Bacteriol. 2015 197(3):563).

Key words: Molecular bacteriology, Infectiology, Interactions host-bacteria, Legionella pneumophila, Virulence, Interactions host-Legionella, Amoeba, Macrophages