Combination attenuation offers strategy for live-attenuated coronavirus vaccines 1 2 Vineet D. Menachery1,2, Lisa E. Gralinski2, Hugh D. Mitchell4, Kenneth H. Dinnon III2, Sarah R. 3 Leist2, Boyd L. Yount Jr.2, Eileen T. McAnarney1,2, Rachel L. Graham2, Katrina M. Waters4, 4 Ralph S. Baric2,3. 5 6 1Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA 2Departments of Epidemiology and 3Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA 4Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA Corresponding Author: Ralph S. Baric Address: University of North Carolina at Chapel Hill, 2107 McGavran-Greenberg Hall CB 7435, Chapel Hill, NC 27599-7435 Telephone: 919-966-7991 Fax: 919-966-0584 Email: