This application seeks support for a research-emphasis veterinarian embarking on an independent career as a translational veterinarian-scientist. The applicant proposes to study macrophages as drivers of SARS-CoV2- induced lung damage in humans and mouse models, and will develop novel indicator mice to report SARS-CoV2 cellular targets in mice. This multi-disciplinary approach brings together leading experts in lung biology, macrophage biology, virology, mouse genetics and pulmonary pathology. At Cornell University College of Veterinary Medicine, the applicant will perform research in the laboratories of Drs. David Russell and Dr. Hector Aguilar-Carreño (Department of Microbiology and Immunology), with histopathology analyses performed in the laboratory of Dr. Gerald Duhamel (Department of Biomedical Sciences). For specific hands-on training in lung epithelial repair assays, the applicant will work in the laboratory of Dr. Carla Kim (Harvard Medical School/Children’s Hospital Boston). Dr. Russell, primary mentor, is an expert in macrophage biology and their interaction with several lung pathogens, notably M.tuberculosis and HIV. He has a proven track record in training post-doctoral veterinarian-scientists that have gone on to tenure-track positions with federal research funding. Dr. Aguilar-Carreño has published extensively on the entry and egress of enveloped viruses with emphasis on paramyxoviruses, and recently has adapted his well-described mouse challenge platform for antiviral and vaccine discovery, toward SARS-CoV2. Dr. Duhamel is a veterinary anatomic pathologist with a research focus in infectious disease, including lung pathogens in mice. Finally, Dr. Carla Kim is a pioneer in lung epithelial repair and stem cell biology. Adding breadth and depth to the proposed work, the applicant has assembled a team of enthusiastic collaborators (with two practicing MD physicians), including leaders in mouse genetics and lung injury (Drs. Kahn and Morrisey), hyaluronan biology (Dr. Hascall), and human pulmonary pathology (Dr. Borczuk). The research environment at Cornell is exceptional in the disciplines of infectious disease and comparative pathology, while the combined expertise of Drs. Kim and Borczuk adds a strong translational and integrative focus on drivers of alveolar damage. The proposal will probe how resident and recruited macrophages are dysregulated during SARS-CoV2 in mice, whether dependent on direct viral infection of macrophages or on environmental cues. In Aim 1, reporter mice will be generated to identify SARS-CoV2- infected cells during infection and upon asymptomatic recovery. During Aim 2, the nature of macrophage subsets as viral targets will be studied, and their resulting functional deficits determined using assays developed by Dr. Russell. In Aim 3, viral challenge studies in human Ace2-expressing mice will interrogate macrophages as drivers of alveolar damage, and test whether macrophage interventions improve clinical outcomes in mice. The candidate will begin this research as Senior Research Associate in the Department of Microbiology and Immunology (75% research effort), with an expected junior faculty transition in the independent award phase.