一株类禽型H1N1猪流感病毒的进化分析与分子特征

Phylogenetic Analysis on a Strain of Avian-like H1N1 Subtype Swine Influenza Virus and Determination of Its Molecular Characteristics

2017年12月,上海市一养殖场饲养的猪出现咳嗽、呼吸困难、发热及迅速转归等病症。将猪鼻拭子接种鸡胚进行病毒分离,对血凝试验阳性样品在SPF鸡胚上进一步纯化、增殖,分离到1株猪流感病毒(A/swine/Shanghai/1205/2017)。采用RT-PCR对分离毒株进行全基因组扩增测序,利用DNAstar软件,对测序基因片段进行整个阅读框的核苷酸序列同源性比对分析,并用MEGA6绘制遗传进化树并分析氨基酸位点。结果显示:分离毒株为H1N1亚型,其8个基因片段均属于类禽型H1N1进化分支,没有出现不同基因型流感病毒片段之间的重组;分离株HA蛋白的裂解位点序列为PSIQSR↓G,具有典型低致病性流感病毒的分子特征。本毒株的分离鉴定为分析我国大陆地区的猪流感流行状况和分子特征提供了参考。

In December 2017,pigs in a farm of Shanghai City appeared a series of symptoms,including cough, dyspnea and fever,and the diseased pigs recovered rapidly. Then the nasal swab samples collected from pigs were inoculated into SPF chicken embryos for virus isolation,after further purifying and proliferating the positive samples detected by haemagglutination assay(HA),one strain of swine influenza virus(A/swine/Shanghai/1205/2017) was isolated. The whole genome of the isolate was amplified and sequenced by RT-PCR,the nucleotide sequence homology of the whole reading frame was analyzed by the DNAstar software,and then the genetic evolution tree was designed using MEGA 6 to analyze the amino acid sites. The results showed that the isolated strain was identified as H1N1 subtype influenza virus,and its eight gene fragments were classified into evolutionary branch of avian-like H1N1,with no any recombination among influenza virus fragments of various genotypes. The cleavage site sequence of its HA protein was PSIQSR ↓ G,indicating the typical molecular characteristics of low pathogenicity influenza virus. Therefore,the isolation and identification of H1N1 strain would provide some reference for analyzing the epidemic situation and molecular characteristics of swine influenza in China's Mainland.