1. National Engineering Technology Research Center for Combined Vaccines, Wuhan, People’s Republic of China
2. The Second Laboratory of Viral Vaccine Research, Wuhan Institute of Biological Products Co. Ltd., Wuhan, People’s Republic of China
3. School of Animal Science and Technology, School of Animal Medicine, Huazhong Agricultural University, Wuhan, People’s Republic of China
4. China National Biotec Group Company Limited, Beijing, People’s Republic of China