1. Department of Chemistry, University of Wisconsin-Madison College of Letters and Sciences, Madison, Wisconsin 53706, United States
2. McArdle Laboratory for Cancer Research and Carbone Cancer Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin 53705, United States
3. Institute for Molecular Virology, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
4. Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110, United States
5. Influenza Research Institute, Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, Wisconsin 53705, United States
6. Division of Virology, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan
7. The Research Center for Global Viral Diseases, National Center for Global Health and Medicine Research Institute, Tokyo 162-8655, Japan
8. Pandemic Preparedness, Infection and Advanced Research Center (UTOPIA), University of Tokyo, Tokyo 162-8655, Japan