猪伪狂犬病病毒变异株的分离鉴定及其gE基因的分子特征

Identification of glycoprotein E characteristic in pseudorabies virus variants from swine

2014年猪伪狂犬病(PR)在我国规模化猪场大范围发生,本实验室在吉林和黑龙江省发病猪场分离到2株PRV,命名为PRV-JL1和PRV-HLJ1。病毒在Vero细胞中能够产生典型的PRV细胞病变,将PRV-JL1以103LD50的剂量感染3只6月龄绵羊,接种羊在5 d^8 d内全部死亡,均出现典型的PR症状及组织病理学变化。将PRV-JL1及PRV-HLJ1与近3年来本实验室分离鉴定的及GenBank中登录的来源于国内10多个省份的32个PRV株和17个经典PRV株的gE核苷酸序列进行比对分析,结果表明:近3年分离的PRVs与本实验室之前分离的变异株PRV-HeN1的同源性在97.1%~99.5%,而与经典株PRV双城株(PRV-S)的同源性在96.6%~99.1%。以gE氨基酸序列建立的进化树分析结果显示,近3年分离的PRVs形成一个相对独立于经典株的新分支。以上结果表明变异株已成为我国主要流行的病毒株,而且变异株均在gE蛋白的第48位和第492位各存在1个天冬氨酸的插入。该插入突变可以作为鉴定PRV变异株的分子特征,其生物学意义有待于进一步研究。

Swine pseudorabies （PR） has occurred in many large scale pig farms in China since 2011. In the present study, two isolates of PR virus （PRV） were identified which were isolated from Jilin and Heilongjiang province, designated PRV-JL1 and PRV-HLJ1, respectively. The isolates were able to cause typical CPE in Vero cells. In addition, three 6-month sheep were artificially infected with the PRV-JL1 at a dose of 103 LD50 and all the sheep died within 5 to 8 days with the typical PR symptoms and histopathologic changes. Furthermore, the gE gene sequences were analyzed including 32 sequences available in GenBank, the 16 sequences from the isolates containing the PRV-JL1 and PRV-HLJ1 isolated in our laboratory since 2012 and a classic strain of PRV-S （1980）. The results suggested that the PRVs isolated in recent ttu＇ee years shared 97.1% to 99.5% identity with variant PRV-HeN1 isolated in 2012, and 96.6% to 99. 1% identity with the classic strain PRV-S. Phylogenetic analysis of the gE showed that the PRVs isolated in recent three years formed a relatively independent branch far from the classic PRVs. The alignmentresults revealed that the PRVs isolated since 2012 had the same sequence features with two insertions of Asp at sites of 48 and 492 in gE, which were considered to be the molecular Marker of the variant PRVs prevailing in China.