Project Summary/Abstract Resident microbiota profoundly influence physiologic responses in multiple organs and altered microbiota (dysbiosis) and bacterial metabolites are linked to numerous inflammatory, metabolic, neoplastic and behavioral disorders. Gnotobiotic models offer a means to address causality and mechanisms of these host- microbe interactions. The National Gnotobiotic Rodent Resource Center (NGRRC) provides an essential resource for local, regional and national multidisciplinary investigators to examine physiologic and pathogenic differences in GF and gnotobiotic (selectively colonized) vs. conventionally raised mice, functional relevance of bacterial genes and explore host/microbe, microbe/ microbe and dietary/microbe interactions. Our NGRRC’s operations were severely impacted by our university’s COVID19-related shutdown from mid- March through June 1. Our resources are now stretched to accommodate our Center’s return to normal function and to accommodate the backlog of services related to shipping mice, deriving new GF mouse strains from outside investigators and training facility managers at new potential gnotobiotic units in other institutions. To accommodate this backlog of deferred training sessions and GF derivations that are on our waitlist, to revamp our breeding colonies and prepare for the large backlog in shipping, we need to hire and train an additional animal care technician that is beyond our current budget. Because UNC continued full salaries of personnel whether they worked remotely or were unable to work a full schedule, while supplementing payments for those who worked onsite as essential (emergency) personnel, our personnel expenses continued at full (or higher) levels than pre-pandemic, despite producing far fewer mice for experimental use by our investigators both internal and external to UNC. Thus, our budget is unable to accommodate hiring of an additional animal care technician to increase our required production level. We request additional funding to temporarily expand activities to address backlogs in 3 areas corresponding to our parent award’s Specific Aims. This expansion will be accomplished by hiring an additional research technician and expanding activities of existing highly trained personnel who are paid in part from other funding sources. Aim 1. Provide GF and gnotobiotic WT and mutant mice, their tissues and cells to NIH-funded investigators. Aim 2. Derive additional GF genetically engineered mouse strains for NIH investigators. Aim 4. Train personnel to develop murine gnotobiotic facilities in other institutions