9[1]Sagar M Goyal.J V et al D iagn invest, 1993, 5:656～664 (1993)
10[2]A ndreyer V G. Genetic variation and pHylogenetic rela2tion ship s of 22porcine rep roductive and respiratory syn2drome virus ( PRRSV ) field strain based on sequenceanalysis of open reading frame 5[J ]. Arch Virol, 1997,142: 993～1002.
