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Infect Genet Evol. 2016 Sep;43:108-22. doi: 10.1016/j.meegid.2016.04.033. Epub 2016 May 13.

Molecular epidemiology, phylogeny and evolution of Legionella.

Author information

1
Institut Pasteur, Unité de Biologie des Bactéries Intracellulaires, France; CNRS, UMR 3525, 28, Rue du Dr Roux, 75724 Paris, France.
2
CIRI, International Center for Infectiology Research, Inserm, U1111, CNRS, UMR 5308, Université Lyon 1, École Normale Supérieure de Lyon, Lyon F-69008, France.
3
CIRI, International Center for Infectiology Research, Inserm, U1111, CNRS, UMR 5308, Université Lyon 1, École Normale Supérieure de Lyon, Lyon F-69008, France; French National Reference Center of Legionella, Institut des agents infectieux, Hospices Civils de Lyon, Lyon, France.

Abstract

Legionella are opportunistic pathogens that develop in aquatic environments where they multiply in protozoa. When infected aerosols reach the human respiratory tract they may accidentally infect the alveolar macrophages leading to a severe pneumonia called Legionnaires' disease (LD). The ability of Legionella to survive within host-cells is strictly dependent on the Dot/Icm Type 4 Secretion System that translocates a large repertoire of effectors into the host cell cytosol. Although Legionella is a large genus comprising nearly 60 species that are worldwide distributed, only about half of them have been involved in LD cases. Strikingly, the species Legionella pneumophila alone is responsible for 90% of all LD cases. The present review summarizes the molecular approaches that are used for L. pneumophila genotyping with a major focus on the contribution of whole genome sequencing (WGS) to the investigation of local L. pneumophila outbreaks and global epidemiology studies. We report the newest knowledge regarding the phylogeny and the evolution of Legionella and then focus on virulence evolution of those Legionella species that are known to have the capacity to infect humans. Finally, we discuss the evolutionary forces and adaptation mechanisms acting on the Dot/Icm system itself as well as the role of mobile genetic elements (MGE) encoding T4ASSs and of gene duplications in the evolution of Legionella and its adaptation to different hosts and lifestyles.

KEYWORDS:

Epidemiology; Experimental evolution; HGT; ICEs; Legionella pneumophila; Phylogeny; T4ASS

PMID:
27180896
DOI:
10.1016/j.meegid.2016.04.033
[Indexed for MEDLINE]

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