LAUSR

Cyp51 contribution to azole resistance has been broadly studied and characterized in Aspergillus fumigatus, whereas it remains poorly investigated in other clinically relevant species of the genus, such as those of section Nigri. In this work, we aimed to analyze the impact of cyp51 genes (cyp51A and cyp51B) on the voriconazole (VRC) response and resistance of Aspergillus niger and Aspergillus tubingensis. ABSTRACT Cyp51 contribution to azole resistance has been broadly studied and characterized in Aspergillus fumigatus, whereas it remains poorly investigated in other clinically relevant species of the genus, such as those of section Nigri. In this work, we aimed to analyze the impact of cyp51 genes (cyp51A and cyp51B) on the voriconazole (VRC) response and resistance of Aspergillus niger and Aspergillus tubingensis. We generated CRISPR-Cas9 cyp51A and cyp51B knockout mutants from strains with different genetic backgrounds and diverse patterns of azole susceptibility. Single-gene deletions of cyp51 genes resulted in 2- to 16-fold decreases of the VRC MIC values, which were below the VRC epidemiological cutoff value (ECV) established by the Clinical and Laboratory Standards Institute (CLSI), irrespective of their parental strains’ susceptibilities. Gene expression studies in the tested species confirmed that cyp51A participates more actively than cyp51B in the transcriptional response of azole stress. However, ergosterol quantification revealed that both enzymes comparably impact the total ergosterol content within the cell, as basal- and VRC-induced changes to ergosterol content were similar in all cases. These data contribute to our understanding of Aspergillus azole resistance, especially in non-A. fumigatus species.