Population structure in a fungal human pathogen is potentially linked to pathogenicity

Author: mycolabadmin
8/15/2025
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Summary

Researchers studied 300 strains of Aspergillus flavus, a fungus that causes serious infections in people and damages crops. They found that strains causing human infections are not randomly distributed but instead belong to specific genetic groups, particularly a newly identified group called population D. This discovery suggests that certain genetic traits make some strains more likely to infect humans, providing insights that could lead to better treatments and prevention strategies.

Background

Aspergillus flavus is a clinically and agriculturally important fungus causing severe human infections and crop losses. Previous research on genetic diversity within A. flavus has been limited to microsatellite markers or agricultural isolates, leaving the relationship between environmental and clinical isolates largely unexplored. Understanding population structure and its connection to pathogenicity could inform clinical and agricultural interventions.

Objective

To examine population structure, phylogeny, and pan-genome composition of A. flavus using genomic data from 300 isolates (117 clinical and 183 environmental) from 13 countries. The study aimed to determine if clinical isolates are non-randomly distributed across populations and identify genetic elements associated with human pathogenicity.

Results

Five A. flavus populations were identified including a newly described population D. Population D contained >85% clinical isolates while population B contained <5% clinical isolates. Clinical isolates were non-randomly distributed across the phylogeny (Fritz and Purvis D = 0.245, p < 0.0001). Population D was enriched for genes involved in carbohydrate metabolism, lipid metabolism, and hydrolase activity, while many clinical isolates lacked the aflatoxin biosynthetic gene cluster.

Conclusion

Clinical isolates of A. flavus are concentrated in specific populations rather than randomly distributed, particularly in the newly defined population D, which shows distinct genetic features. This contrasts with A. fumigatus where clinical isolates are evenly distributed, highlighting different evolutionary trajectories to pathogenicity. The identification of population-specific genetic differences provides a foundation for future investigations into the genetic basis of A. flavus human pathogenicity.

Published in:Nature Communications,
Study Type:Comparative Genomic Study,
Source: PMID: 40817095, DOI: 10.1038/s41467-025-62777-9