1. Department of Veterinary Microbiology, Faculty of Agriculture, Iwate University, Ueda 3-18-8, Morioka, Iwate 020-8550
2. Department of Microbiology and Immunology, Tokyo Women's Medical University School of Medicine, Shinjuku-ku, Tokyo 162-8666
3. Department of Bacteriology, Hirosaki University School of Medicine, Hirosaki 036-8562
4. Department of Technical Support and Development, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage-ku, Chiba-shi 263-8555, Japan