Project #3:Active Vaccination and Immunotherapy Against Coccidioidomycosis

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Project Summary An estimated 350,000 people in the United States become infected with Coccidioides annually. There is an unmet need to develop better chemotherapies and a vaccine for active immunization and/or immunotherapy against coccidioidomycosis (CM). We have previously created a recombinant chimeric polypeptide antigen (rCpa1) composed of the most immunogenic fragments of 3 previously identified Coccidioides antigens and 5 human T-cell epitopes. The bacterial-expressed rCpa1 is loaded into yeast glucan-chitin particles (GCPs) to create GCP-rCpa1 protein vaccine. The latter stimulates a robust Th1 and Th17 response and confers protection for human MHC II-expressing HLA-DR4 transgenic mice against a lethal pulmonary infection with both species of Coccidioides. The challenges to advance a protein vaccine to clinical readiness are to produce high quantity and quality of the rCpa1 antigen and to validate human immune response to the vaccine. In this project, we propose to create two types of formulation methods using mRNA and vector-based delivery and adjuvant systems. The vaccine recepients will express the coccidioidal antigen in vivo to prime their own immune system. Our central hypothesis is that an optimized rCpa-1-based vaccine using an mRNA or vector delivery/adjuvant platform will stimulate robust Th1 and Th17 immunity against CM. These two delivery platforms can be easily scaled up to produce safe vaccines for preclinical and clinical testing. The GCP-rCpa1 protein vaccine will be used as a benchmark for comparison. There are 3 specific aims. Aim 1: We will design DNA constructs for in vitro transcription of mRNAs that encode Coccidioides rCpa1 antigen. IVT-mRNAs will be loaded into GCPs to create GCP-rCpa1-mRNA vaccines. The second approach will create a vector-based vaccine using a Francisella novicida mutant (Fn-iglD). Wild typle Fn rarely causes tularemia, while F. tularensis (Ft) is highly virulent. Fn-iglD is highly attenuated and it protects both rats and macaques againt a lethal pulmonary Ft infection. Fn-iglD also elictis a mixed Th1/Th17 immunity and it is currently under formulation for clinical safety trial. We will create a Fn-iglD-rCpa1 vaccine. The antigen expression levels of these platforms and their capacity to stimulate cytokine production in human monoctyic THP-1 cells and murine macrophages will be determined. Aim 2: The newly created vaccines that show both good antigen expression and capable of eliciting cytokine production will be further evaluated for their efficacy, immune correlates and protective mecahnisms. We will apply the HLA-DR4 murine model of CM and human blood cells to delineate immune correlates and protective mechanisms using a global immune gene profiling method and confirmed with immiunlogical methods in our laboratories. Aim3: We will establish a murine immunotherapy model of CM for evaluating treatment efficacy of the most protective vaccine alone or in combination with an azole or the newly identified drugs in Project #1 and Project #2.