1. Department of Biochemistry and Molecular Biology, College of Bioengineering, Dalian University, Dalian, Liaoning 116622, China.
2. Department of Microbiology and Immunology, College of Animal Science of Jilin Agricultural University, Changchun, Jilin 130118, China.
3. Institute of Military Veterinary Science, Academy of Military Medical Science, Changchun, Jilin 130062, China.