1. Department of Obstetrics and Gynecology, Institute of Clinical Medicine; University of Tsukuba; Tsukuba Ibaraki 305
2. Department of Microbiology, Institute of Basic Medical Science; University of Tsukuba; Tsukuba Ibaraki 305
3. Department of Immunology; Otsuka Pharmaceutical Co., Ltd.; Tokushima Tokushima 770
4. Department of Medical Biology and Parasitology; Jichi Medical School; Tochigi 329-04