1 College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu Province, P. R. China.
2 Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu Province, P. R. China.
3 Institute of Comparative Medicine, Yangzhou University, Yangzhou, Jiangsu Province, P. R. China.
4 College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu Province, P. R. China zqwang@yzu.edu.cn.