Whole Genome Sequence analysis of colonization and infective Aspergillus fumigatus clinical isolates reveals no differences in the content of virulence genes

Aspergillus fumigatus is the opportunistic airborne pathogen with the biggest clinical impact on human pathogenesis. Despite that a restricted number of virulence factors have been described, none of them are able to fully account for differences in a strain's virulence. In this study we analyzed the whole genome sequence of a set of clinical, environmental and experimental A. fumigatus isolates, to determine their virulence profile. We assessed the presence of virulence factors and performed a comparative genomics analysis to identify genomic differences among them. To this end, we created a database containing a total of 244 genes associated with virulence and classified them according to their function and biological processes: thermotolerance, resistance to immune responses, cell wall structure, toxins and secondary metabolites, allergens, nutrient uptake and signaling and regulation. We identified the presence of all tested genes in the genome sequence of 7 out of 9 isolates, showing no difference between clinical isolates coming from a fatal infection and a colonization setting. Taken together, our genomic analysis reveals that members of these species with different source of isolation are potentially pathogenic, nevertheless, the differences in the strain-specific virulence are not only determined by the presence or absence of these factors at the genomic level.