1. College of Animal Science and Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, China.
2. Emergency Centre for the Control of Transboundary Animal Diseases, Food and Agriculture Organization of the United Nations (FAO), Beijing 100600, China.
3. Poultry Institute, Chinese Academy of Agricultural Science, Yangzhou 225125, China.
4. Laboratory of Zoonoses, China Animal Health and Epidemiology Center, Qingdao 266032, China.