1. Donan-NOSAI, Donan Agricultural Mutual Relief Association, 25–16 Misugicho, Yakumo, Futami-gun, Hokkaido 049–3114, Japan
2. School of Veterinary Medicine, Rakuno Gakuen University, 582 Midorimati, Bunnkyoudai, Ebetsu, Hokkaido 069–8501, Japan
3. College of Veterinary Medical Science, Ohio State University, 601 Vernon L. Tharp St., Columbus, OH 43210–1089, U.S.A.
4. Ishikari-NOSAI, Ishikari Agricultural Mutual Relief Association, 7–4–1 Seiryu, Chitose, Hokkaido 066–0081, Japan
5. Department of Veterinary Medicine, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa 252–8510, Japan
6. Central Research Laboratories, Nippon Zenyaku Kogyo Co., Ltd., 1–1 Aza Tairanoue, Sasagawa, Asakamachi, Koriyama, Fukushima 963–0196, Japan