Project Summary: Invasive pulmonary aspergillosis (IPA) caused by Aspergillus fumigatus is a major cause of morbidity and mortality in immune-compromised patients despite the availability of antifungal drugs. The global emergence of azole drug resistance is a major factor contributing to poor disease outcomes; however, azole drug-resistant A. fumigatus isolates contribute to only about 5% of infections. A major gap in knowledge is how azole sensitive isolates tolerate azole drugs and contribute to poor disease outcomes with mortality rates in excess of 50%. To this end, we have identified an uncharacterized long non-coding RNA (lncRNA) afu-182 that negatively correlates with azole drug response and is a driver of azole drug tolerance in the laboratory and clinical isolates. In this proposal, we will use genomics, genetics, biochemical approaches to define the mechanism of afu-182 mediated azole drug tolerance in A. fumigatus. In specific Aim 1), we will define the pathways regulating azole tolerance and afu-182 regulon to understand the molecular mechanisms involved in azole tolerance. In Aim 2), we will define the afu-182 expression in vivo under azole stress in a murine model of invasive pulmonary aspergillosis. Successful completion of proposed aims has tremendous potential to improve clinical outcomes by defining mechanisms involved in azole tolerance and declassifying binary resistant/susceptible spectrum for fungal isolates. This will help design better treatment strategies for azole susceptible infections to achieve better disease outcomes.