伪狂犬病病毒HLJ-2013株gB基因及蛋白特性的初步分析

Preliminary analysis of the characteristics of the gB protein of pseudorabies virus strain HLJ-2013

gB蛋白是介导猪伪狂犬病病毒(PRV)侵入宿主细胞的关键因子之一,同时也是重要的病毒抗原蛋白。为研究PRV分离株HLJ-2013 gB蛋白与其它参考株的差异性,本研究将HLJ-2013株与GenBank中的80条PRV参考株分别进行gB基因序列及推导氨基酸序列的比对,并分析其与参考株gB氨基酸位点的差异;基于最大似然法构建了该基因及推导的氨基酸序列的系统发育树;利用间接免疫荧光试验初步比较了HLJ-2013株与PRV SC株gB抗原性的差异。结果显示,基于gB核苷酸序列及氨基酸序列构建的进化树显示HLJ-2013株处于一个独立于我国分离株的单独分支上,表明其起源可能同国内病毒株不同;与参考株相比,其氨基酸序列中存在27个氨基酸差异位点,并有一个独特的插入基序S75P76G77;免疫荧光鉴定结果显示,PRV SC株gB的一株单克隆抗体不与HLJ-2013株病毒发生特异性结合反应,提示两株病毒gB蛋白的抗原性可能存在差异。本研究初步表明HLJ-2013株的gB和其它病毒株的gB存在遗传及生物学特性上的明显差异,提示HLJ-2013类病毒的流行可能会给我国猪伪狂犬病的防控带来潜在威胁。

The gB protein of pseudorabies virus(PRV)plays a key role in virus entry,and is also one of the major viral antigens.To characterize the property of the gB protein of PRV strain HLJ 2013,we compared the nucleotide and amino acid sequences of the gB with other 80 reference strains from GenBank and constructed two Maximum-Likelihood phylogenetic trees.The gB antigenicity difference of PRV between strain HLJ-2013 and strain SC was compared by an indirect immunofluorescence assay.The results showed that the gB of HLJ-2013 was located in a unique branch,indicating that PRV strain HLJ-2013 was from a different origin compared with other PRV strains in China.There were 27 amino acid differences between the gB of HLJ-2013 and the reference strain.An insertion of three amino acids(S75P76G77)was observed only in the gB of HLJ-2013.The indirect immunofluorescence assay results showed that a monoclonal antibody against the gB of PRV SC didn’t react with the gB of HLJ 2013,indicating the presence of antigenicity variations in the gB of PRV strains.This study demonstrates that the gB of HLJ-2013 contains genetic and biological variations comparing to others,therefore,much attention should be paid on the potential threat of HLJ-2013-like viruses to control the prevalence of PR in China.