1. State Key Laboratory of Veterinary Biotechnology Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences Harbin China
2. Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine Iowa State University Ames IA USA
3. Technical Centre for Animal, Plant, and Food Inspection and Quarantine of Shanghai Customs Shanghai China
4. Department of Population Health, College of Veterinary Medicine University of Georgia Athens GA 30602 USA
5. Department of Infectious Disease, College of Veterinary Medicine University of Georgia Athens Georgia 30602 USA