PROJECT SUMMARY – OVERALL: Structure-based design of broadly protective coronavirus vaccines We propose a highly synergistic research Program focused on developing two broadly protective coronavirus vaccine candidates: a pan-sarbecovirus vaccine at the end of Year 2, and a pan-betacoronavirus at the end of Year 5. Our Program brings together six research groups with complementary and synergistic expertise in structure-based vaccine design, coronavirus structural biology and immunity, the immunology of vaccines, animal model development, and viral evolution. This team emerged in response to the SARS-CoV-2 pandemic to rapidly develop an ultrapotent protein nanoparticle vaccine that is currently in Phase I/II clinical trials, with funding secured for Phase III. Our Program comprises three Scientific Projects supported by four Scientific Cores and an Administrative Core. This structure will allow maximal synergy between our groups in pursuit of the three central outputs of our Program: Tools, Antibodies, and Vaccines. Tools: we will develop reverse genetic platforms for producing panels of wild-type and indicator viruses and new animal models of human coronavirus disease that can be used to assess neutralizing and protective breadth. We will also develop platforms for deep mutational scanning of spike proteins spanning the betacoronavirus phylogeny to inform antigen design and model development and assess the breadth and mutational resistance of vaccine-elicited antibodies. Antibodies: our Program will identify conserved epitopes in betacoronavirus spike proteins targeted by cross-reactive antibodies, and characterize the structural basis for broad neutralization and protection at high resolution. This information will be used to iteratively inform structure-based antigen and vaccine design and will generate antibody therapeutics that could blunt the effects of future zoonotic spillovers. Vaccines: we recently showed that co-displaying multiple hemagglutinin antigens on the same self-assembling protein nanoparticle, an approach termed mosaic nanoparticle display, induced broadly protective humoral immunity against influenza. We will combine this approach with cutting-edge computational methods for stabilizing glycoprotein antigens and designing nanoparticle scaffolds tailored to display coronavirus spikes in optimal geometries. We expect the resultant nanoparticle vaccine candidates to elicit potent and broadly protective antibody responses against conserved epitopes in betacoronavirus spikes. We will mechanistically and functionally evaluate the performance of these vaccine candidates formulated with clinically relevant adjuvants in relevant animal models, including nonhuman primates. To facilitate successful transfer to industry partners, we will prepare technology transfer packages for the two lead vaccine candidates that will be produced by our Program: a pan-sarbecovirus vaccine at the end of Year 2, and a pan-betacoronavirus vaccine at the end ...