PROJECT SUMMARY (Core B: Organoid Core) Infectious disease research is substantially hampered by lack of experimental models necessary to study interactions between pathogens and target tissues; a glaring deficiency amplified by the recent COVID-19 pandemic. The recent advent of 3D organoid methods embodies a more physiologic in vitro infectious disease platform. Over the past 5 years, the Stanford NAMSED U19 Center has operated an Organoid Core, led by Calvin Kuo, which has distributed approximately 74 organoid lines for modeling infectivity of gastrointestinal pathogens, resulting in numerous collaborative publications. The Organoid Core has also produced new air- liquid interface (ALI) organoids that maintain epithelium and infiltrating immune populations en bloc without reconstitution (Cell, 2018) and created new protocols for long-term, feeder-free, chemically defined human lung distal organoid culture, as well as novel human nasal sinus organoids (Cell Stem Cell, 2020). The overall goal for Core B (Organoid Core) in our renewal application of the Stanford NAMSED U19 for a Stanford/UNC Biomimetic U19 Research Center is to expand upon our previous success and provide novel ex vivo models for studying gastrointestinal and respiratory pathogens. Thus, Core B will serve as a central biohub for our Center by generating and distributing next-generation human gastrointestinal and respiratory organoid cultures to support Projects 1-3. In addition to these core responsibilities, the Kuo lab will optimize innovative organoid-based assays that will provide additional support for Projects 1-3 and resources for the global research community. In Aim 1, human “epithelial-only” organoids from the stomach, small intestine, distal lung and nasal airways will be generated, characterized, and distributed for Project 1 (H. pylori, S. Typhi, S. Typhimurium), Project 2 (rotavirus), and Project 3 (SARS-CoV-2, MERS, pre-epidemic coronaviruses and 1918 influenza H1N1 virus). There has been a particular lack of organoid methods incorporating endogenous immune populations without reconstitution. Thus, Aim 2 develops innovative ALI organoid methods preserving epithelial and endogenous infiltrating immune cells en bloc for defining cross-talk between epithelial and immune compartments during GI and pulmonary infections. Lastly, Aim 3 optimizes multiplexed organoid platforms for pathogen infection and drug screening to provide novel methods for evaluating infection, therapeutics and immune responses. Overall, Core B of the Stanford/UNC Biomimetic U19 Research Center leverages leading-edge expertise in primary 3D human organoid culture for the study of enteric and respiratory pathogens. Additionally, we capitalize on novel organoid methods preserving both the epitheilal and immune components to provide innovative holistic tools to dissect pathways involved during pathogenic infection, with both basic and translational implications.