1. College of Medicine and Medical Research Institute, Chungbuk National University, 12 Gaeshin-Dong Heungduk-Ku, Cheongju 361-763, Republic of Korea
2. College of Veterinary Medicine, Chungnam National University, 220 Gung-Dong, Yuseoung-Gu, DaeJeon 305-764, Republic of Korea
3. Chungbuk Veterinary Service Laboratory, Cheongju 360-171, Republic of Korea
4. Division of Bioscience and Technology, College of Life and Environmental Science, Korea University, Seoul, Republic of Korea