猪伪狂犬病病毒流行株gE基因的遗传变异分析及其对仔猪致病性的初步研究

摘要

Objective] This study aimed to investigate the genetic variation of gE gene of an epidemic pseudorabies virus (PRV) strain and its pathogenicity to piglets. [Method] By serial passage in Vero cel s, a PRV strain was isolated from the brain tissues of stil born fetuses delivered by sows with suspected PRV infection and preliminarily identified by PCR. gE gene of the isolated PRV strain was ampli-fied and sequenced for phylogenetic analysis. In addition, the pathogenicity of the isolated PRV strain to 6-week-old piglets was evaluated. [Result] A PRV strain was successful y isolated and named PRV N5B strain, which could proliferate in Vero cel s and TCID50 of the 15th generation virus liquid reached 107.125/0.1 ml. Specific bands could be amplified by PCR. gE gene in the isolated PRV strain was 1 740 bp in length. A phylogenetic tree was constructed based on ful-length gE se-quences, which showed that PRV N5B strain and PRV strains isolated since 2012 were clustered into the same independent category and shared 99.7%-100% ho-mology of nucleotide sequences. Compared with related sequences published previ-ously, there were insertions of three consecutive bases at two loci. Animal experi-ments showed that intranasal inoculation of 6-week-old piglets with 2 ml of PRV N5B strain (106/0.1 ml) led to a mortality rate of 100%. [Conclusion] In this study, genetic variability of gE gene in PRV N5B isolate and its pathogenicity to piglets were analyzed, which provided a theoretical basis for the development of new vac-cines to prevent and control porcine pseudorabies.%[目的]了解我国猪伪狂犬病病毒流行株 gE基因的遗传变异特性以及其对仔猪的致病性。[方法]利用 Vero 细胞从疑似伪狂犬病病毒（PRV）引起的流产死胎猪的脑组织进行病毒分离。通过PCR进行初步鉴定，对分离株 gE基因序列进行系统进化树分析以及该病毒对6周龄左右仔猪的致病性试验。[结果]成功分离到1株 PRV 毒株，命名为 PRV N5B 株，该病毒能在 Vero 细胞上增值，在15代 TCID50达到107.125/0.1 ml；PCR检测可扩增出特异性条带；gE基因全长1740 bp，系统进化树分析表明分离株与2012年以来新流行的毒株属于同一个相对独立的分支,核苷酸同源性高达99.7%～100%；而与以往发表的国内外相关序列比较，在2个不同的位置分别有3个连续碱基的插入。动物试验表明，2 ml的该病毒（106/0.1 ml）滴鼻接种能使6周龄左右仔猪100%死亡。[结论]该研究中的 PRV N5B分离株 gE基因的遗传变异特性以及其对仔猪的致病性试验对于目前流行的猪伪狂犬病的防控及新的疫苗的研发提供理论依据。