1. Biosafety Research Center, Foods, Drugs and Pesticideds, 582-2, Shioshinden, Fukude-cho, Iwata-gun, Shizuoka 437-1213, Japan.
2. Department of Veterinary Pathology and Research Institute of Biosciences, School of Veterinary Medicine, Azabu University, 1-17-71 Fuchinobe, Sagamihara, Kanagawa 229-8501, Japan