1. Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA
2. Division of Virology, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
3. The Research Center for Global Viral Diseases, National Center for Global Health and Medicine Research Institute, Tokyo, Japan
4. Department of Special Pathogens, International Research Center for Infectious Diseases, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan