1. National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Ibaraki 305–0856, Japan
2. Department of Microbiology, Meiji Pharmaceutical University, Kiyose, Tokyo 204–8588, Japan
3. School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069–8501, Japan
4. Tokachi NOSAI, Taiki, Hokkaido 089–2106, Japan
5. Aichi NOSAI, Okazaki, Aichi 444–0816, Japan
6. Ishikari NOSAI, Ebetsu, Hokkaido 069–0055, Japan
7. Okhotsk NOSAI, Kitami, Hokkaido 099–0879, Japan
8. School of Veterinary Medicine, Azabu University, Sagamihara, Kanagawa 252–5201, Japan