1. Department of Comparative Medicine; Pig Research Institute Taiwan; Chunan Miaoli 35046 Taiwan
2. Department of Veterinary Medicine; National Taiwan University; Taipei 106 Taiwan
3. Department of Veterinary Medicine; National Pingtung University of Science and Technology; Pingtung 912 Taiwan
4. Bureau of Animal and Plant Health Inspection and Quarantine; Council of Agriculture; Taipei 100 Taiwan