1. Institute of Animal Husbandry and Veterinary, Xizang Academy of Agricultural and Animal Husbandry Sciences, Key Laboratory of Animal Genetics and Breeding on Tibetan Plateau, Ministry of Agriculture and Rural Affairs, Lhasa 850000, China
2. School of Public Health, Lanzhou University, Lanzhou 730000, China
3. National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, China