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Updated: May 25, 2026
Gene Expression Profiling of Infecting Microbes Using a Digital Bar-coding Platform
Published on: January 13, 2016
Global changes in gene expression by the opportunistic pathogen Burkholderia cenocepacia in response to
Jennifer S Tolman1, Miguel A Valvano
1Infectious Diseases Research Group, Department of Microbiology & Immunology, University of Western Ontario, London, Ontario, N6A 5C1, Canada.
Background:
Burkholderia cenocepacia is an opportunistic pathogen causing life-threatening infections in patients with cystic fibrosis. The bacterium survives within macrophages by interfering with endocytic trafficking and delaying the maturation of the B. cenocepacia-containing phagosome. We hypothesize that B. cenocepacia undergoes changes in gene expression after internalization by macrophages, inducing genes involved in intracellular survival and host adaptation.
Results:
We examined gene expression by intracellular B. cenocepacia using selective capture of transcribed sequences (SCOTS) combined with microarray analysis. We identified 767 genes with significantly different levels of expression by intracellular bacteria, of which 330 showed increased expression and 437 showed decreased expression. Affected genes represented all aspects of cellular life including information storage and processing, cellular processes and signaling, and metabolism. In general, intracellular gene expression demonstrated a pattern of environmental sensing, bacterial response, and metabolic adaptation to the phagosomal environment. Deletion of various SCOTS-identified genes affected bacterial entry into macrophages and intracellular replication. We also show that intracellular B. cenocepacia is cytotoxic towards the macrophage host, and capable of spread to neighboring cells, a role dependent on SCOTS-identified genes. In particular, genes involved in bacterial motility, cobalamin biosynthesis, the type VI secretion system, and membrane modification contributed greatly to macrophage entry and subsequent intracellular behavior of B. cenocepacia.
Conclusions:
B. cenocepacia enters macrophages, adapts to the phagosomal environment, replicates within a modified phagosome, and exhibits cytotoxicity towards the host cells. The analysis of the transcriptomic response of intracellular B. cenocepacia reveals that metabolic adaptation to a new niche plays a major role in the survival of B. cenocepacia in macrophages. This adaptive response does not require the expression of any specific virulence-associated factor, which is consistent with the opportunistic nature of this microorganism. Further investigation into the remaining SCOTS-identified genes will provide a more complete picture of the adaptive response of B. cenocepacia to the host cell environment.
Insights
Burkholderia cenocepacia adapts to macrophage environments by altering gene expression, enhancing its survival and replication. This metabolic adaptation is key to its opportunistic infections, particularly in cystic fibrosis patients.
Area of Science:
- Microbiology
- Molecular Biology
- Pathogenesis
Background:
- Burkholderia cenocepacia is an opportunistic pathogen causing severe infections in cystic fibrosis patients.
- It survives in macrophages by disrupting phagosome maturation.
- Gene expression changes are hypothesized to aid intracellular survival.
Purpose of the Study:
- To investigate the gene expression profile of B. cenocepacia within macrophages.
- To identify genes crucial for intracellular survival and host adaptation.
Main Methods:
- Selective Capture of Transcribed Sequences (SCOTS) combined with microarray analysis was used.
- Gene expression levels of intracellular B. cenocepacia were examined.
- The impact of gene deletions on bacterial behavior was assessed.
Main Results:
- 767 genes showed altered expression in intracellular B. cenocepacia (330 increased, 437 decreased).
- Intracellular gene expression reflects environmental sensing, response, and metabolic adaptation.
- Genes for motility, cobalamin biosynthesis, type VI secretion, and membrane modification are vital for macrophage entry and intracellular survival.
- Intracellular B. cenocepacia is cytotoxic and spreads to neighboring cells.
Conclusions:
- B. cenocepacia successfully adapts to the macrophage phagosomal environment, replicates, and exhibits cytotoxicity.
- Metabolic adaptation is crucial for B. cenocepacia survival within macrophages.
- The adaptive response does not rely on specific virulence factors, aligning with its opportunistic nature.
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