1. College of Veterinary Medicine, Kyungpook National University, Daegu 702-701, Korea.
2. Lee Gil Ya Cancer and Diabetes Institute, Gachon University of Medicine and Science, Incheon 406-840, Korea.
3. College of Veterinary Medicine, Chonnam National University, Kwangju 500-757, Korea.
4. National Veterinary Research and Quarantine Service, Anyang 430-824, Korea.
5. College of Veterinary Medicine, Chungnam National University, Daejeon 302-305, Korea.