1. Graduate Institute of Molecular and Comparative Pathobiology, School of Veterinary Medicine, National Taiwan University (NTU), No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan, R. O. C.
2. Graduate Institute of Veterinary Medicine, School of Veterinary, Medicine, NTU, Taipei 10617, Taiwan, R. O. C.
3. Laboratory Animal Center, Tzu-Chi University, No. 701, Sec. 3, Zhongyang Rd., Hualien 97004, Taiwan, R. O. C.
4. Laboratory Animal Center, National Chiao Tung University, No. 75, Bo-Ai St., Hsinchu 30068, Taiwan, R. O. C.