1. Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, Sichuan, PR China
2. Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China
3. Research Center of Avian Diseases, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, PR China