1. Division of Infectious Animal Disease Research, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Ibaraki, Japan
2. The United Graduate School of Veterinary Sciences, Gifu University, Gifu, Gifu, Japan
3. Iwate Prefectural Chuo Livestock Hygiene Service Center, Takizawa, Iwate, Japan
4. Aichi Prefectural Chuo Livestock Hygiene Service Center, Okazaki, Aichi, Japan