Aspergillus fumigatus is a ubiquitous fungus and the main agent of aspergillosis, a common fungal infection in the immunocompromised population. Triazoles such as itraconazole and voriconazole are the common first-line drugs for treating aspergillosis. However, triazole resistance in A. fumigatus has been reported in an increasing number of countries. While most studies of triazole resistance have focused on mutations in the triazole target gene cyp51A, >70% of triazole-resistant strains in certain populations showed no mutations in cyp51A. To identify potential non-cyp51A mutations associated with triazole resistance in A. fumigatus, we analyzed the whole genome sequences and triazole susceptibilities of 195 strains from 12 countries. These strains belonged to three distinct clades. Our genome-wide association study (GWAS) identified a total of six missense mutations significantly associated with itraconazole resistance and 18 missense mutations with voriconazole resistance. In addition, to investigate itraconazole and pan-azole resistance, Fisher's exact tests revealed 26 additional missense variants tightly linked to the top 20 SNPs obtained by GWAS, of which two were consistently associated with triazole resistance. The large number of novel mutations related to triazole resistance should help further investigations into their molecular mechanisms, their clinical importance, and the development of a comprehensive molecular diagnosis toolbox for triazole resistance in A. fumigatus.
Keywords: Aspergillus; Aspergillus fumigatus; antifungal resistance; comparative genomics; itraconazole; triazoles; voriconazole; whole-genome sequencing.