Project Summary – Project 3 (Fungus) A high skin fungal burden is a defining feature of Candida auris, and this burden is associated with increased risk of disease. The first step in this process is the ability of strains to attach and adhere, on both biotic and abiotic surfaces. This attachment also is the first step in the formation of biofilms, which are linked with both persistence and antifungal drug resistance. However, the cell biology and genetic circuitry underlying the ability of C. auris to colonize the skin are not known. Our long-term goal is to identify the genetic determinants and regulation of C. auris skin colonization and thus persistence and transmission between individuals. This application details experiments to address a fundamentally important gap in our knowledge of mechanisms by which C. auris is a successful human fungal pathogen. We propose three complementary genomics approaches to explore the biology of C. auris skin colonization. We recently developed genetic tools for interrogating this organism, giving us unprecedented power to analyze the genes required for C. auris colonization. In Aim 1, we will use a population genetics and genome-wide association approach to identify naturally-occurring variants that are associated with increased attachment. In Aim 2, we will use a forward genetics screening approach and an in vitro model to uncover new effectors and regulators of C. auris skin attachment. In Aim 3, we will use experimental evolution to identify variants of concern for skin colonization, and connect this with functional experiments to test the impact of these variants. Together, these studies will advance new concepts for how C. auris can regulate adherence, colonization, and outbreak potential.