PRRSV流行株Nsp2、ORF5和ORF3基因序列的分析

Nsp2,ORF5 and ORF3 Gene Sequence Analyses of PRRSV Isolate strains

采用RT-PCR方法扩增2006年--2007年从江西、湖南、海南、广东等4省的不同猪场病猪体内分离的11株猪繁殖与呼吸综合征病毒（PRRSV）流行株的Nsp2、ORF5和ORF3基因，并进行序列分析。结果表明，11个PRRSV流行株的Nsp2均发生30个氨基酸的不连续缺失，缺失位置与JXA1毒株相同；11个PRRSV流行株的ORF5、ORF3基因和JXA1相应序列的核苷酸同源性分别为99．2％～99．8％、99．1％～99．6％，氨基酸同源性分别为98．0％～99．5％、98．4％～99．6％；11个PRRSV流行株之间ORF5基因的核苷酸同源性和氨基酸同源性分别为98．8％～100．0oA、98．0oA～100．0％，其中5个流行株的ORF3基因的核苷酸和氨基酸同源性分别为99．0％～99．6％、98．8％～99．69，6。根据Nsp2所建立的遗传系统发育树可知这11个PRRSV流行株与JXA1株的亲缘关系很近。

11 PRRSV isolates newly were isolated from nosopoietie pigs in Jiangxi, Hunan, Hainan and Guangdong provinces respectively. The sequence analyses of Nsp2, ORF3 and ORF5 showed that these isolates had a discontinuous deletion of 30 amino acids in Nsp2. The ORF5 and ORF3 of 11 PRRSV isolates shared 99.2%-99.8% and 99.1%-99.6% nucleotide homologies, and 98.0%-99.5%, 98.4%-99.6% ami- no acid homologies with that of JXA1, respectively. The ORF5 of 11 PRRSV isolates shared 99. 0%- 100.0% ,nucleotide homologies and 98.0%-100.0% amino acid homologies with each other. The ORF3 of 5 PRRSV isolates shared 99.0%-99.6% nucleotide homologies and 98.8%-99.6% amino acid homologies with each other. The phylogenetic tree suggested that the isolates from different provinces had close relationship, which were evolved by same strain.