1. Department of Infectious Diseases, Yamagata University Faculty of Medicine, Iida-Nishi, Yamagata 990-9585, Japan
2. Department of Microbiology, Kanazawa Medical University School of Medicine, Uchinada, Ishikawa 920-0293, Japan
3. Drug Analysis Department, Kashima Laboratory, Toxicological Science Division, Medi-Chem Business Segment, Mitsubishi Chemical Medience Corporation, Sunayama 14, Kamisu-City, Ibaraki, 314-0255, Japan
4. Influenza Virus Research Center, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama, Tokyo 208-0011, Japan