1. Department of Veterinary Public Health, Nippon Veterinary and Life Sciences University, Musashino, Tokyo 180-8602, Japan
2. Department of Biomedical Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
3. Kitasato-Otsuka, Biomedical Assay Laboratories Co, Ltd, Sagamihara, Kanagawa 228-8555, Japan