1. Tochigi Prefectural Kenou Livestock Hygiene Service Center, 6-8 Hiraidekogyodanchi, Utsunomiya, Tochigi 321-0905, Japan
2. Tochigi Prefectural Kenhoku Livestock Hygiene Service Center, 2-12-14 Midori, Nasushiobara, Tochigi 329-2713, Japan
3. National Institute of Animal Health, National Agriculture and Food Research Organization, National Research and Development Agency, 3-1-5 Kannondai, Tsukuba, Ibaraki 305-0856, Japan