1. Department of Applied Biological Science Tokyo University of Agriculture and Technology 3-5-8 Saiwai-cho, Fuchu Tokyo 183-8509 Japan
2. Graduate School of Science and Engineering Yokohama National University 79-5 Tokiwa-dai, Hodogaya-ku Yokohama Kanagawa 240-8501 Japan
3. Research and Education Center for Prevention of Global Infectious Diseases of Animals Tokyo University of Agriculture and Technology 3-5-8 Saiwai-cho, Fuchu Tokyo 183-8509 Japan