1. Department of Emergency and Critical Care Medicine, Tsukuba Memorial Hospital, 1187-299, Kaname, Tsukuba, Japan
2. Department of Health Services Research, Faculty of Medicine, University of Tsukuba, 305-8577, Tsukuba, Japan
3. Division of Molecular Virology & Genetics, Joint Research Center for Human Retrovirus Infection, Kumamoto University, 860-0811, Kumamoto, Japan
4. Department of Medicine, Muribushi Okinawa Center for Teaching Hospitals, 901-2132, Okinawa, Japan
5. Division of Systems Virology, Institute of Medical Science, The University of Tokyo, 108-8639, Minato-ku, Tokyo, Japan
6. Graduate School of Frontier Sciences, The University of Tokyo, 277-8561, Kashiwa, Chiba, Japan
7. Department of General Medicine, Juntendo University, 113-8421, Tokyo, Japan