1. Department of Microbiology, College of Veterinary Medicine, Seoul National University, Seoul 151-742, Korea.
2. Department of Bacteriology, National Veterinary Research and Quarantine Service, Anyang 430-824, Korea.
3. Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164-7040, USA.
4. KRF Zoonotic Disease Priority Research Institute, College of Veterinary Medicine, Seoul National University, Seoul 151-742, Korea.