[1] CAAS, Harbin Vet Res Inst, Minist Agr, Vet Publ Hlth Lab, Harbin 150001, Peoples R China
[2] CAAS, Harbin Vet Res Inst, State Key Lab Vet Biotechnol, Harbin 150001, Peoples R China
[3] Emory Univ, Sch Med, Dept Microbiol & Immunol, Atlanta, GA 30322 USA