1. Division of Virology Department of Microbiology and Immunoslogy Institute of Medical Science University of Tokyo Tokyo Japan
2. Department of Pathobiological Sciences School of Veterinary Medicine University of Wisconsin‐Madison Madison WI USA
3. Exotic Disease Inspection Division Laboratory Department Animal Quarantine Service Ministry of Agriculture, Forestry and Fisheries Aichi Japan
4. Department of Special Pathogens International Research Center for Infectious Diseases Institute of Medical Science University of Tokyo Tokyo Japan