1 Organ Transplantation Service, The University of Tokyo Hospital, Tokyo, Japan.
2 Artificial Organ and Transplantation Division, Department of Surgery, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
3 Division of Gastroenterological and Hepatobiliary Surgery and Organ Transplantation, Department of Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan.
4 Division of Virology, Department of Infection and Immunity, Jichi Medical University School of Medicine, Shimotsuke, Japan.