1. First Department of Internal Medicine; Kagoshima University; Kagoshima Kagoshima 890-8520 Japan
2. Division of Persistent & Oncogenic Viruses, Center for Chronic Viral Diseases, Faculty of Medicine; Kagoshima University; Kagoshima Kagoshima 890-8520 Japan
3. Division of Hematology; Jiaikai Imamura Hospital; Kagoshima Kagoshima 892-0824 Japan