1. State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences , Harbin 150069 , China
2. Department of Veterinary Medicine, Institute of Microbiology and Epizootics, Centre for Infection Medicine, Freie Universität Berlin , Berlin 14163 , Germany
3. Department of Veterinary Medicine, Veterinary Centre for Resistance Research (TZR), Freie Universität Berlin , Berlin 14163 , Germany
4. College of Veterinary Medicine, Xinjiang Agricultural University , No. 311, Nanchang Road, Urmuqi 830052 , P. R. China