1. National Institute of Health Sciences, 3-25-26, Tonomachi, Kawasaki-ku, Kawasaki, Kanagawa 210-9501, Japan
2. Division of Veterinary Science, Department of Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan
3. Department of Infectious Diseases, Hokkaido Institute of Public Health, Kita19 Nishi 12, Kita-ku Sapporo, Hokkaido 060-0819, Japan
4. Murayama Branch, National Institute of Infectious Diseases. 4-7-1, Gakuen, Musashimurayama, Tokyo 208-0011, Japan
5. Department of Applied Veterinary Science, the United Graduate School of Veterinary Science, Gifu University, 1-1, Yanagido, Gifu 501-1193, Japan