1. Department of Agricultural Chemistry; The University of Tokyo; Yayoi 1-1 Bunkyo-ku Tokyo 113 Japan
2. Department of Dermatology, Faculty of Medicine; The University of Tokyo; Hongo 5 Bunkyo-ku Tokyo 113 Japan
3. Department of Virology; Medical Institute of Bioregulation, Kyushu University; Fukuoka 812 Japan