1. 1National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, 1-15-1 Tokura, Kokubunji, Tokyo 185-8511, Japan
2. 2Gifu Prefectural Institute of Health and Environmental Sciences, 1-1 Naka-Fudogaoka, Kagamigahara, Gifu 504-0838, Japan
3. 3Department of Veterinary Public Health, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan