2015-2020年天津地区猪伪狂犬病病毒gB、gC、gE基因遗传变异分析

Genetic Variation Analysis of gB,gC and gE Genes of PorcinePseudorabies Viruses Isolated in Tianjin During 2015-2020

为掌握天津地区猪伪狂犬病病毒(Pseudorabies virus,PRV)的流行及遗传变异情况,本研究对2015-2020年天津地区分离的20个分离株的gB、gC和gE基因进行扩增、测序,并与参考毒株序列进行比对分析。相似性分析结果显示,分离株与2012年后中国变异株相比,3种基因核苷酸及编码氨基酸序列相似性分别为:gB基因均为99.9%~100%;gC基因为99.7%~100%和99.4%~100%;gE基因为99.7%~100%和99.6%~100%。遗传进化和序列比对分析结果显示,依据gB、gC、gE基因绘制遗传进化树均可将PRV毒株分为GⅠ型和GⅡ型,天津分离株属于GⅡ型;其中19个分离株与PRV变异株遗传关系较近,属于同一亚分支,并存在相同的氨基酸变异位点;另外1个分离株(TJBD6株)gB和gE基因与PRV变异株遗传关系较近,氨基酸变异位置与PRV变异株一致,但其gC基因与经典株Ea株遗传关系较近,且核苷酸和氨基酸序列相似性为100%。上述结果表明,2015年以来天津地区流行的PRV毒株存在经典株和变异株2种类型,其中变异株为主要流行株。本次研究初步调查了天津地区PRV分子流行特征,可为猪伪狂犬病防控提供依据。

To understand the epidemic and genetic variation of porcine Pseudorabies virus(PRV)in Tianjin area,gB,gC and gE genes of 20 isolated strains from Tianjin during 2015 to 2020 were amplified,sequenced and analyzed with the sequences of reference strains.Similarity analysis showed that when compared with the Chinese strain after 2012,the homology of nucleotide and amino acid of the three genes were as follows:gB gene were both 99.9%-100%;gC gene were 99.7%-100%and 99.4%-100%,respectively;gE gene were 99.7%-100%and 99.6%-100%,respectively.Phylogenetic and sequence alignment analysis showed that according to gB,gC,gE genes phylogenetic trees,PRV strains could be divided into GⅠand GⅡgenotypes,isolated strains from Tianjin were clustered in GⅡgenotype.19 isolated strains showed a closer genetic relationship with the PRV variant strains,distributed in the same gene subtype,and had the same amino acid variation characteristic.The gB and gE genes of the other strain(TJBD6)showed a closer genetic relationship with the PRV variant strains,and the amino acid variation positions were the same as those of the PRV variant strains,however,its gC gene was closely related with the classical strain Ea,and the nucleotide and amino acid sequence similarity was 100%.These results indicated that there were two types of PRV strains prevalent in Tianjin since 2015:Classical strains and variant strains,and the variant strains were the main prevalent strains.This study preliminarily investigated the molecular epidemiological characteristics of PRV in Tianjin area,which could provide a basis for the prevention and control of pseudorabies.