1. Department of Veterinary Microbiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan3
2. Department of Biological Chemistry, Faculty of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan1
3. Department of Immunology, National Institute of Infectious Disease, Tokyo 113-8657, Japan2
4. Central Laboratory, Kyoritu Shouji Co. Ltd, Ibaraki, Japan4