Mycobacterium abscessus virulence traits unraveled by transcriptomic profiling in amoeba and macrophages

PLoS Pathog. 2019 Nov 8;15(11):e1008069. doi: 10.1371/journal.ppat.1008069. eCollection 2019 Nov.

Abstract

Free-living amoebae are thought to represent an environmental niche in which amoeba-resistant bacteria may evolve towards pathogenicity. To get more insights into factors playing a role for adaptation to intracellular life, we characterized the transcriptomic activities of the emerging pathogen Mycobacterium abscessus in amoeba and murine macrophages (Mϕ) and compared them with the intra-amoebal transcriptome of the closely related, but less pathogenic Mycobacterium chelonae. Data on up-regulated genes in amoeba point to proteins that allow M. abscessus to resist environmental stress and induce defense mechanisms, as well as showing a switch from carbohydrate carbon sources to fatty acid metabolism. For eleven of the most upregulated genes in amoeba and/or Mϕ, we generated individual gene knock-out M. abscessus mutant strains, from which ten were found to be attenuated in amoeba and/or Mϕ in subsequence virulence analyses. Moreover, transfer of two of these genes into the genome of M. chelonae increased the intra-Mϕ survival of the recombinant strain. One knock-out mutant that had the gene encoding Eis N-acetyl transferase protein (MAB_4532c) deleted, was particularly strongly attenuated in Mϕ. Taken together, M. abscessus intra-amoeba and intra-Mϕ transcriptomes revealed the capacity of M. abscessus to adapt to an intracellular lifestyle, with amoeba largely contributing to the enhancement of M. abscessus intra-Mϕ survival.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amoeba / genetics*
  • Amoeba / growth & development
  • Amoeba / microbiology
  • Animals
  • Bacterial Proteins / genetics
  • Macrophages / metabolism*
  • Macrophages / microbiology
  • Mice
  • Mycobacterium Infections, Nontuberculous / genetics*
  • Mycobacterium Infections, Nontuberculous / microbiology
  • Mycobacterium abscessus / genetics
  • Mycobacterium abscessus / isolation & purification
  • Mycobacterium abscessus / pathogenicity*
  • Transcriptome*
  • Virulence / genetics*
  • Virulence Factors / genetics*

Substances

  • Bacterial Proteins
  • Virulence Factors

Grants and funding

V.D. was supported by French Cystic Fibrosis Patients Association Vaincre la Mucoviscidose (VLM) grant RF20150501377. Work in the laboratory of R.B. was supported by the Agence National de Recherche (ANR-10-LABX-62-IBEID, ANR-16-CE15-0003, and ANR-16- CE35-0009), VLM (grant RF20180502259), the Fondation pour la Recherche Médicale (DEQ20130326471), and the Institut Pasteur. The Transcriptome and Epigenome Platform is a member of the France Génomique consortium (ANR10‐NBS‐09‐08). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.