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Differential Role of the T6SS in Acinetobacter baumannii Virulence

Guillermo D Repizo1, Stéphanie Gagné1, Marie-Laure Foucault-Grunenwald2

  • 1Bases Moléculaires et Structurales des Systèmes Infectieux, CNRS UMR 5086, Université Lyon 1, Institut de Biologie et Chimie des Protéines, Lyon, France.

Plos One
|September 25, 2015
PubMed

Insights

Acinetobacter baumannii strains show varied type VI secretion system (T6SS) activity. Only one non-clinical isolate demonstrated T6SS-mediated killing and virulence, highlighting strain-specific differences in this important pathogen.

Area of Science:

  • Microbiology
  • Bacterial Pathogenesis
  • Molecular Biology

Background:

  • Acinetobacter baumannii is a significant hospital-acquired pathogen.
  • Multi-drug resistant (MDR) strains pose a growing global health threat.
  • The type VI secretion system (T6SS) is a key virulence factor in many bacteria.

Purpose of the Study:

  • To compare the functional activity of the T6SS across different A. baumannii strains.
  • To investigate the role of T6SS in interbacterial competition and host colonization.
  • To determine if T6SS functionality differs between clinical and non-clinical isolates.

Main Methods:

  • Genomic analysis and transcriptional profiling of T6SS loci.
  • In vitro killing assays against Escherichia coli.
  • Competition assays with other relevant bacterial pathogens.
  • Galleria mellonella larval infection model to assess virulence.

Main Results:

  • All tested A. baumannii strains possessed the T6SS gene locus and showed transcription.
  • Only the non-clinical isolate DSM30011 exhibited T6SS-dependent killing of E. coli.
  • DSM30011 outcompeted other bacterial pathogens and a type strain.
  • T6SS of DSM30011 was essential for Galleria mellonella colonization.

Conclusions:

  • T6SS functionality in A. baumannii is strain-specific.
  • The T6SS contributes to interbacterial competition and virulence.
  • Non-clinical isolates may possess more active T6SS than clinical MDR strains.
  • T6SS represents a potential target for therapeutic intervention against A. baumannii.

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