浙江省猪繁殖与呼吸综合征病毒ORF5基因的遗传变异分析

Genetic analysis of porcine reproductive and respiratory syndrome virus ORF5 gene from Zhejiang province

为了解2004-2009年猪繁殖与呼吸综合征病毒(PRRSV)ORF5基因的变异情况,从浙江省各个地区采集了109份临床疑似病料,共检测到61份ORF5基因阳性,经序列测定得到可比序列117个。在核苷酸序列分析中,发现2004-2005年PRRSV ORF5序列之间同源性为83.6%～99.3%,2006年同源性最高达98.3～99.2%,2008-2009年同源性又有所降低。在氨基酸主要位点分析中,分离毒株的非中和表位27～30位点与美洲株相比,2004-2006年大部分毒株的29aa由A29-V29,而2007-2009年大部分毒株的29aa又由V29-A29;在表位37～45aa中,所有39位点处由L39-I39;在表位80～197aa中,从2004-2009年185aa大部分都发生了变异,由V185-A185,第189位点由I189-L189。在蛋白生化特性分析中,发现与参考株VR2332(AY150564)和CH-1a(AY032626)相比,浙江省PRRSV-GP5蛋白的第100～106位亲水性、表面可及性明显增加,抗原性指数也有所提高,而与参考毒株JX-06-2-EU480750相似。该试验结果说明随着时间的推移,PRRSV ORF5基因发生明显的变异。

To explore sequence variation of porcine reproductive and respiratory syndrome virus ORF5 during the period of 2004-2009,109 suspected clinical samples were collected from Zhejiang province,in which 61 samples were tested as positive and 117 comparable sequences were obtained by sequencing. Sequence analysis revealed that PRRSV isolates in the period of 2004-2005 shared 83.6%-99.3% nucleotide identities with each other,the highest of 2006 with 98.3%-99.2%,and a slight decrease of 2008-2009. Major amino acid sequence comparison of isolated virus strains with the American strain showed that 29 aa of most isolated virus strains of 2004-2006 mutated from A29 to V29 ,29 aa and 37-45 aa of 2007-2009 mutated from V29 to A29 and L^39 to I39 ,respectively, most 185 aa and 189 aa of 2004-2009 mutated from V185 to A185 and I^189 to L1^189. Protein biochemical characteristic analysis suggested that the hydrophilic and accessibility of the domain 100-106 re- markably increased,availability index of the antigens enhanced to some extent by comparison of PRRSV-GP5 protein of Zhejiang region with reference strains VR2332 （AY150564） and CH-la （AY032626） ,moreover,these index shared a homology with reference strain JX-06-2-EU480750. In conclusion,there are a variation of PRRSV ORF5 in the course of time.