2018年伪狂犬病病毒的流行特征及其遗传变异分析

Epidemiological and Evolutionary Characteristics of Pseudorabies Virus in China in 2018

为了了解当前伪狂犬病病毒(PRV)在我国猪群中的流行现状及其遗传变异情况,本研究利用PCR的方法对2018年1-12月来源于我国28个省、市、自治区的1 328份疑似猪伪狂犬病发病猪的组织样品开展了PRV-gE的检测及病毒的分离鉴定,同时针对所分离的病毒的gB、gC和gE基因进行PCR扩增和DNA测序,并展开遗传变异分析。结果显示,共有92份样品为PRV-gE基因检测阳性,阳性检出率为6.93%。从92份PRV-gE阳性样品分离到13株PRV。分别基于gB基因部分片段、gC和gE基因进行遗传变异分析发现13株PRV与我国2012年以后流行的毒株(如HeN1等变异株)亲缘关系较近,而与2012年以前所分离的毒株(如Ea等经典毒株)的亲缘关系较远;此外,绝大多数中国分离株与国外分离毒株(如NIA-3、Bartha、Kaplan等)在遗传进化树中位于不同的进化分支;相对于国外分离株及国内早期流行的经典毒株而言,13株PRV分离株的gB、gC和gE蛋白中均存在许多特征性的氨基酸位点变异。本研究对于了解我国PRV流行现状及当前流行的PRV毒株的生物学特征具有十分重要的意义。

This experiment was conducted to study the epidemiological and phylogenetic characteristics of swine pseudorabies virus(PRV) currently circulating in China. A total of 1 328 samples from pigs with suspected PRV infection were collected from 28 provinces of China in 2018 for PRV-gE detection by PCR and virus isolation;DNA sequencing was also performed on the gB, gC and gE genes of the PRVs isolated herein and the sequences were used for DNA alignments as well as phylogenetic analysis. The results showed that: 1) A total of 92 samples collected herein were positive for PRV-gE by PCR, with an average positive detection rate of 6.93%. Thirteen PRV strains were finally isolated from these 92 PRV-gE positive samples;2) Phylogenetic analysis on either gB, gC and/or gE showed that the 13 PRVs isolated herein were close to the epidemic PRV strains in China after 2012 but were not close to those circulating in China before 2012;most of the PRV strains isolated from China were located on a different evolutionary branch with those from the other countries such as NIA-3, Bartha, and Kaplan;3) There were so many amino acid changes with the gB, gC and/or gE proteins in the 13 PRVs isolated herein compared to those in the viruses isolated from the other countries as well as those isolated from China before 2012. These results indicated that the PRVs currently circulating in China were mainly the variant strains that showed different phylogenetic and genetic characteristics from those prevalent in China before 2012 as well as those circulating in the other countries, representing a serious problem.