Improving knockout capacity for Coccidioides

Project 1 Supplement Summary: Virulence Gene Discovery in Coccidioides The focus of Project 1 is virulence gene discovery in Coccidioides. Despite the impact of Coccidioides infection, the molecular understanding of virulence mechanisms in this fungus is limited. Only a handful of Coccidioides genes have been implicated any virulence-relevant traits. Given the need to accelerate drug

discovery and resolve the public health crisis posed by this fungus in the endemic areas, it is imperative to dissect virulence strategies used by Coccidioides to manipulate the host. Here we apply powerful systems-level tools to identify virulence-relevant genes. Such a landmark discovery effort will help open up the field at long last,

providing a rich source of virulence genes to serve as new therapeutic targets. The ability of Coccidioides to cause disease depends on an elaborate developmental transition from saprophytic soil form to host form. Specifically, the hyphal form of the organism produces arthroconidia, which disperse easily and can be inhaled by mammalian hosts. Once inside the host lung, arthroconidia germinate,

enlarge, and undergo nuclear division and segmentation to form large spherules filled with vegetative endospores. Rupture of the spherules allows release of endospores and dissemination of the fungus to other sites. Given the critical role of spherule development in disease progression, a major focus of this project is the

genomic and genetic dissection of this process. We will identify candidate genes that govern spherulation by a combination of molecular approaches. We are disrupting these candidate genes and assessing their roles in spherulation. Our Coccidioides knockout workflow requires more personnel time per strain than we had allocated

in the parent award. To meet this demand, we request support for salary to add an additional Coccidioides molecular geneticist to contribute to knockout construction and phenotyping under the current supplement. We do not propose a change in the scope of the grant.