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Updated: Jun 30, 2025
Isolation and Selection of Entomopathogenic Fungi from Soil Samples and Evaluation of Fungal Virulence against Insect Pests
Published on: September 28, 2021
Strain heterogeneity in a non-pathogenic fungus highlights factors contributing to virulence
David C Rinker1, Thomas J C Sauters1, Karin Steffen1
1Department of Biological Sciences and Evolutionary Studies Initiative, Vanderbilt University, Nashville, Tennessee, USA.
Abstract:
Fungal pathogens exhibit extensive strain heterogeneity, including variation in virulence. Whether closely related non-pathogenic species also exhibit strain heterogeneity remains unknown. Here, we comprehensively characterized the pathogenic potentials (i.e., the ability to cause morbidity and mortality) of 16 diverse strains of Aspergillus fischeri, a non-pathogenic close relative of the major pathogen Aspergillus fumigatus. In vitro immune response assays and in vivo virulence assays using a mouse model of pulmonary aspergillosis showed that A. fischeri strains varied widely in their pathogenic potential. Furthermore, pangenome analyses suggest that A. fischeri genomic and phenotypic diversity is even greater. Genomic, transcriptomic, and metabolomic profiling identified several pathways and secondary metabolites associated with variation in virulence. Notably, strain virulence was associated with the simultaneous presence of the secondary metabolites hexadehydroastechrome and gliotoxin. We submit that examining the pathogenic potentials of non-pathogenic close relatives is key for understanding the origins of fungal pathogenicity.
Insights
Closely related non-pathogenic fungi, like Aspergillus fischeri, show significant variation in disease-causing potential. This fungal strain heterogeneity offers insights into the origins of pathogenicity.
Area of Science:
- Mycology
- Pathogenomics
- Fungal immunology
Background:
- Fungal pathogens display considerable strain heterogeneity, impacting disease severity.
- The extent of strain variation in closely related non-pathogenic fungal species is largely unexplored.
- Understanding this variation is crucial for predicting and managing fungal diseases.
Approach:
- Evaluated the pathogenic potential of 16 diverse Aspergillus fischeri strains using in vitro immune assays and in vivo mouse models.
- Conducted pangenome, genomic, transcriptomic, and metabolomic analyses to assess strain diversity and identify virulence-associated factors.
- Investigated the role of secondary metabolites in fungal virulence variation.
Key Points:
- Aspergillus fischeri strains exhibited significant differences in their ability to cause morbidity and mortality in a mouse model.
- Pangenome analysis revealed extensive genomic and phenotypic diversity within A. fischeri.
- Virulence correlated with the presence of specific secondary metabolites, including hexadehydroastechrome and gliotoxin.
Conclusions:
- Non-pathogenic fungal relatives can possess a wide range of pathogenic potentials, challenging traditional classifications.
- Examining the pathogenicity of non-pathogenic species provides critical insights into the evolutionary origins of fungal virulence.
- This research highlights the importance of strain-level characterization in understanding fungal disease dynamics.
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