1. Department of Immunology and Parasitology, Yamagata University School of Medicine, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan
2. Department of Obstetrics and Gynecology, Faculty of Medicine, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa 903-0215, Japan
3. Central Institute for Experimental Animals, 1430 Nogawa, Miyamae, Kawasaki 216-0001, Japan
4. Research Institute for the Functional Peptides, 4-3-32 Shimojomachi, Yamagata 990-0823, Japan
5. Experimental Research Center for Infectious Disease, Institute for Virus Research, Kyoto University, 53 Kawahara-cho Shogoin, Sakyo-ku, Kyoto 606-8507, Japan