山东省部分地区猪伪狂犬病病毒分离鉴定及TK基因遗传变异分析

ISOLATION, IDENTIFICATION AND PHYLOGENETIC ANALYSIS OF TK GENE OF PSEUDORABIES VIRUS IN SHANDONG PROVINCE

为了解当前山东省猪伪狂犬病病毒(Pseudorabies virus,PRV)流行特点,本研究对2018年来自山东省不同地区的10份伪狂犬疑似病料进行PRV的分离鉴定,并对分离株的TK基因进行了序列测定及遗传变异分析。结果表明,共分离到7株PRV,其TK基因核苷酸和氨基酸序列的同源性分别为99.1%~99.8%和98.7%~99.4%,与参考毒株TK基因核苷酸和氨基酸序列的同源性分别为97.8%~99.9%和97.2%~99.7%,而且7株分离株与国内报道的PRV变异株的核苷酸和氨基酸序列的同源性均高于欧美毒株。对TK基因的核苷酸序列分析发现,与欧美参考株相比,分离株和国内变异株在其碱基第644-645位由AC突变为GT,导致其氨基酸第215位由苏氨酸(T)突变为缬氨酸(V)。TK基因的遗传进化树分析结果表明,本研究中7株分离株分别与国内之前报道的JS-2012、HeN1、TJ以及ZMD2012等变异株位于两个相对独立的分支上,亲缘关系较近,而都与NIA3、Becker等欧美毒株以及疫苗株Kaplan(Bartha-K61株)的遗传距离较远。结果表明,本研究所得7株分离株均应属于PRV变异毒株。

To better understand the current epidemiology of pseudorabies virus(PRV)in Shandong province,the present study was conducted for isolation,identification and phylogenetic analysis of TK gene of pseudorabies virus.Total 7 PRV isolates were obtained in 2018 from 10 samples collected from different parts of Shandong province.These PRV isolates were sequenced for their phylogenetic analysis.The results showed that these 7 PRV isolates shared nucleotide and amino acid homologies of 99.1%-99.8%and 98.7%-99.4%.While compared with the reference strains,they had nucleotide and amino acid homologies of 97.8%-99.9%and 97.2%-99.7%.It was noted that these 7 isolates shared higher nucleotide and amino acid identities with the Chinese variant strains than the European and American strains.In addition,alignment of nucleotide sequences of the TK gene revealed mutations from AC to GT at the positions of 644-645 in these 7 isolates and Chinese variants,resulting in the 215th amino acid changed from threonine(T)to valine(V).Phylogenetic analysis of TK gene showed that these 7 isolates were clustered to two relative independent branches with early Chinese variants including strains JS-2012,HeN2012,TJ2012 and ZMD2012 and shared close genetic relationship but distant from the European and American field strains Spain 2008 and USA 2011 as well as vaccine strain Hungary 2011(Bartha-K61strain).In conclusion,these results showed that all 7 PRV isolates in this research belonged to a variant group.