1. Dairy Hygiene Unit, Division of Pathology and Pathophysiology, Hokkaido Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, 4 Hitsujigaoka, Toyohira, Sapporo, Hokkaido 062-0045, Japan
2. NOSAI Minami, 401-4 Shinotsu, Ebetsu, Hokkaido 067-0055, Japan
3. Healthcare R&D Center, Asahi Kasei Corporation, 2-1 Samajima, Fuji, Shizuoka 416-8501, Japan