猪流行性腹泻病毒湖南分离株ORF3基因克隆与遗传进化分析

Amplification and Genetic Anlysis of the ORF3 Gene of Porcine Epidemic Diarrhea Virus Isolated from Hunan Province

为了解湖南省猪流行性腹泻病毒基因变异情况,研究应用RT-PCR技术对湖南某猪场暴发疑似感染PEDV腹泻仔猪中提取肠道病料组织样品进行研究,同时对病原ORF3基因序列进行扩增与分析。结果显示,12份样品中有3份检测为PEDV阳性,其ORF3基因序列均为675 bp,无碱基插入或缺失,仅出现个别碱基突变,其与我国流行的PEDV变异株核苷酸序列同源性分别为98.8%~99.9%,但与PEDV疫苗株(CV777)同源性相对较低,仅为95.4%~96.3%;系统进化树分析结果显示此次研究的PEDV分离株与我国流行的PEDV变异株聚为同一分支,与疫苗株所处分支相隔较远。研究结果表明该猪场发生了PEDV变异株的流行,相关防治措施需尽快实施。

The present study was to investigate the genetic variation of Porcine epidemic diarrhea virus(PEDV)in Hunan Province.After RNA genomes extraction from the intestinal samples from the piglets,the ORF3 gene sequences were amplified using RT-PCR assay,sequenced,and analyzed.The results showed that 3 of 12 samples were positive for PEDV nucleic acids,and the ORF3 gene sequences were 675 bp in length without nucleic acid deletion or insertion,while several mutations were existed.Further genetic homology analysis showed that these strains in this study displayed high genetic similarity with PEDV variant strains prevalent in China(98.8%-99.9%),and the genetic similarities of which with PEDV vaccine strain(CV777)were 95.4%-96.3%.Phylogenetic tree constructed based on the ORF3 gene sequences analysis revealed that the PEDV strains in this study shared the same branch with the popular PEDV variant strain in China.The results obove indicated the occurrence of PEDV variant strainsin this pig farm,and the relevant control measures should be carried out.