5Sur J H, Doster A R, Christian J S,et al. Porcine reproductive and respiratory syndrome virus replicates in testicular germ cells, alters spermatogenesis ,and induces germ cell death by apoptosis[J] .J Viral,1997, (71) :9170-9179.
6Suarez P , Zardaya R, Martin M J, et al. Phylgenetic relationships of Europema straim of Porcine reproductive and respiratory syndrome virus (PRRSV) inferred from DNA sequences of putative ORF5 and ORF7 genes[J] .Virus Res , 1996, (42) : 159-165.
