1. Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, People's Republic of China
2. Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, Ya'an, Sichuan, People's Republic of China
3. Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan, People's Republic of China