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Quorum sensing modulates the formation of virulent Legionella persisters within infected cells

Nicolas Personnic1, Bianca Striednig2, Emmanuelle Lezan3

  • 1Institute for Medical Microbiology, University of Zürich, Gloriastrasse 30, 8006, Zürich, Switzerland. npersonnic@imm.uzh.ch.

Nature Communications
|November 20, 2019
PubMed

Insights

Legionella pneumophila forms distinct, antibiotic-tolerant subpopulations during infection. This bacterial adaptation, crucial for virulence, is regulated by the Lqs quorum-sensing system in both amoebae and macrophages.

Area of Science:

  • Microbiology
  • Bacterial Pathogenesis
  • Cellular Microbiology

Background:

  • Legionella pneumophila is an opportunistic pathogen causing Legionnaires' disease.
  • It replicates intracellularly in environmental amoebae and human macrophages.
  • Understanding bacterial adaptation during infection is critical for disease control.

Purpose of the Study:

  • To investigate the formation and characteristics of bacterial subpopulations within host cells.
  • To determine the role of the Lqs quorum-sensing system in bacterial adaptation.
  • To assess the virulence and antibiotic tolerance of distinct bacterial subpopulations.

Main Methods:

  • Comparative analysis of replicating and nonreplicating L. pneumophila subpopulations.
  • Proteomic analysis of bacterial populations.
  • Infection models using amoebae and macrophages (naïve and IFN-γ-activated).
  • Genetic manipulation of the Lqs quorum-sensing system.

Main Results:

  • L. pneumophila forms distinct, viable, and metabolically active nonreplicating subpopulations within amoebae.
  • These nonreplicating bacteria exhibit increased antibiotic tolerance, distinct proteomes, and enhanced virulence.
  • The proportion of nonreplicating bacteria is similar in amoebae and activated macrophages, and is regulated by the Lqs system.
  • Nonreplicating bacteria form degradation-resistant compartments.

Conclusions:

  • Virulent, antibiotic-tolerant subpopulations of L. pneumophila are formed during infection of phagocytes.
  • This bacterial adaptation is conserved across evolutionarily distant host cells.
  • The Lqs quorum-sensing system controls the formation of these important subpopulations.

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