Project Summary: RMRBL UC7 Core 3 The Rocky Mountain Regional Biocontainment Laboratory (RMRBL) was conceived concomitant with a Research Center for Excellence in Biodefense / Emerging Infectious Diseases. The outcome of these synergized investments in infrastructure and research was a multidisciplinary team of investigators and core research services. The RMRBL’s ability to respond to emerging and persistent pathogen threats are due to our collective understanding of pathogen characteristics, pathogenesis of infection, immunity and host range. Our prolific history of rapid response to high consequence pathogens posing a threat to public and socioeconomic health is due not only to the diverse strengths of the resident investigator teams, but also our ability to conduct these important studies in BSL3 facilities. Specifically, the CSU RMRBL has strengths in defining and optimizing in vitro culture conditions for pathogens and pathogen inactivation, establishing the requisite animal models to investigate wildlife and domestic animal spillover events and reservoir potential, and vaccine models using both viable and inactivated infectious materials produced in vitro. Further, the CSU RMRBL has expertise in cutting-edge technologies to study microbial physiology and animal models; such as conducting proteomic and metabolomics mass spectrometry analyses, detailed histopathologic analyses using spatial transcriptomics and AI-driven quantitative pathology scoring. Lastly, our collective research teams have established programs for supplying biological reagents that can be robustly used for animal and human clinical research, including inactivated biomaterials that can be safely and reproducibly used outside the BSL3. In this Core, we culminate our collective strengths into one Biocontainment Research Resources Core within the BSL3 facilities of the RMRBL. This resultant pathogen characterization core devises our capacity through independent and highly interactive aims; Aim 1: Natural reservoirs of infection and spillover threat for pathogens of pandemic potential; Aim 2: Reagents and models for vaccine and diagnostics studies for pathogens of pandemic potential; and Aim 3: Pathogen:Host materials processing for molecular mass spectrometry imaging and single cell ‘omics analyses. The RMRBL BSL3 Pathogen Characterization core provides opportunities to synergize activities, expand our resources across the RBL network and to additional partners, forge new technologies within the RMRBL BSL3, and ultimately improve our ability to adapt and rapidly deliver research resources acutely responsive to pathogens possessing a threat to our health systems.