1. Department of Virology, Faculty of Medicine, Kyushu University, Fukuoka, Japan
2. Department of Pediatrics, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
3. Department of Microbiology, Faculty of Veterinary Medicine, Okayama University of Science, Ehime, Japan
4. Laboratory of Medical Virology, Institute for Life and Medical Sciences, Kyoto University
5. National Research Center for the Control and Prevention of Infectious Diseases, Nagasaki University, Nagasaki, Japan