1. Division of Virology, Kawasaki City Institute for Public Health, Kanagawa, Japan
2. Department of Microbiology, Yokohama City University School of Medicine, Kanagawa, Japan
3. Division of Infectious Diseases, Nagano Environmental Conservation Research Institute, Nagano, Japan
4. Division of Virology, Saitama Institute of Public Health, Saitama, Japan
5. Infectious Disease Surveillance Center, National Institute of Infectious Diseases, Tokyo, Japan
6. Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan