1. Division of Virology, Kawasaki City Institute of Public Health, Oshima, Kawasaki-ku, Kawasaki-shi, Kanagawa, Japan
2. Division of Microbiology, Department of Pathology and Microbiology, Nihon University School of Medicine, Oyaguchi Kamicho, Itabashi-ku, Tokyo, Japan
3. Division of Gene Therapy, Research Center for Genomic Medicine, Saitama Medical School, Yamane, Hidaka-shi, Saitama, Japan
4. Infectious Disease Surveillance Center, National Institute of Infectious Diseases, Toyama, Shinjuku-ku, Tokyo, Japan
5. Blood Systems Research Institute, San Francisco, California, USA