1. Department of Virology 1, National Institute of Infectious Disease, Toyama, Shinjuku-ku, Tokyo, Japan
2. Department of International Medical Cooperation, Japan, National Center of Global Health and Medicine, Toyama, Shinjuku-ku, Tokyo, Japan
3. Department of Microbiology, Osaka Medical College, Daigaku-machi, Takatsuki, Osaka, Japan
4. Disease Control and Prevention Center, National Center of Global Health and Medicine, Toyama, Shinjuku-ku, Tokyo, Japan