1. Department of Virology, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama 930-0194, Japan
2. Division of Hematology and Oncology, Shizuoka Children's Hospital, 860 Urusiyama, Shizuoka 420-8660, Japan
3. Institute of Medical Science, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-ku, Kawasaki 216-8511, Japan
4. Research Institute for Microbial Diseases, Osaka University, 3-1 Yamda-Oka, Suita, 565-0871, Japan