1. Advanced Medical Research Center Yokohama City University Yokohama Kanagawa Japan
2. Department of Health Science Gunma Paz University Graduate School of Health Sciences Takasaki Gunma Japan
3. Life Science Laboratory Technology and Development Division Kanto Chemical Co. Inc. Isehara Kanagawa Japan
4. Department of Microbiology School of Medicine Yokohama City University Yokohama Kanagawa Japan
5. Center for Influenza and Respiratory Virus Research National Institute of Infectious Diseases Tokyo Japan
6. Department of Virology III National Institute of Infectious Diseases Tokyo Japan