7Hillen S, von Berg S, Khler K, et al. Occurrence and severity of lung lesions in slaughter pigs vaccinated against Mycoplasma hyopneumoniae with different strategies[ J]. Prey Vet Med, 2014.pii: S0167-5877( 13)00394-2. doi: 10.1016/j. prevetmed. 2014.
8Halbur P G , Paul P S, Frey M L, et al. Comparison of the Pathogenicity of Two US Porcine Reproductive and Respiratory Syndrome Virus Isolates with that of the Lelystad Virus [ J ]. Vet Pathol, 1995, 32: 648-660.
9Thacker E L, Thaeker B J, Young T F, et al. E.ect of vaccination on the potentiation of porcine reproductive and respiratory syndrome virus (PRRSV) -induced pneumonia by Mycoplasma hyopneu- moniae[J]. Vaccine, 2000, 18: 1244-1252.
