1. Department of Veterinary Medicine, Faculty of Agriculture, Iwate University, 3–18–8 Ueda, Morioka-shi, Iwate 020–8550, Japan
2. The United Graduate School of Veterinary Sciences, Gifu University, 1–1 Yanagido, Gifu-shi, Gifu 501–1193, Japan
3. Department of Microbiology, Tokyo Metropolitan Institute of Public Health, 3–24–1 Hyakunin-cho, Shinjuku-ku, Tokyo 169–0073, Japan
4. Department of Bacteriology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1–2–3 Kasumi, Minami-ku, Hiroshima-shi, Hiroshima 734–8551, Japan
5. Department of Microbiology and Immunology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki-shi, Aomori 036–8562, Japan