Correspondence:
Prof Z-G Yuan, College of Veterinary Medicine, South China Agricultural
University, Guangzhou, Guangdong Province, PR China; Y-S Mahmmod,
Infectious Diseases, Department of Animal Medicine, Faculty of
Veterinary Medicine, Zagazig University, Zagazig, Sharkia, Egypt; A/Prof
X-X Zhang, College of Agriculture, South China Agricultural University,
Guangzhou, Guangdong Province, PR China
Email: ziguoyuan@scau.edu.cn; yasserpcr@gmail.com;
xiuxiangzh@scau.edu.cn