2018—2020年福建地区猪瘟病毒E0基因遗传变异分析

Genetic Variation of E0 Gene of Classical Swine Fever Virus from 2018 to 2020 in Fujian Province

为了了解2018—2020年福建地区猪瘟病毒流行及遗传变异情况,收集福建省不同地区临床发病猪的血液和肺脏、脾脏、淋巴结等组织样本1464份,采用RT-nPCR的方法对样品进行CSFV检测,对部分CSFV阳性样品E0基因进行克隆测序。结果显示,CSFV总体阳性率为1.9%(29/1464),并获得13株CSFV E0基因序列。同源性分析发现所得13株CSFV E0基因之间的同源性在82.2%-99.7%,其中11株CSFV E0基因与1.1亚型代表毒株HCLV的核苷酸同源性为99.0%~99.9%,与Shimen株的核苷酸同源性94.1%~95.0%;1株与2.1c型参考毒株HNSD-2012核苷酸同源性为98.2%;1株与2.1d亚型毒株CSFV/JPN/2018核苷酸同源性为99.6%。遗传进化分析发现,10株CSFV与HCLV、C-ZJ-2008、Shimen和Brescia处于同一分支,属于1.1亚型;1株CSFV与HNSD-2012等位于同一分支,属于2.1c亚亚型;1株与CSFV/JPN/2018等位于同一分支,属于2.1d亚亚型。氨基酸序列分析发现,13株毒株与HCLV等代表毒株在重要的Rnase活性位点高度保守,其中2株2.1亚型毒株与HCLV毒株相比,其在第35位非关键氨基酸残基上发生由G→E的突变。结果表明福建地区CSFV流行情况趋向多样化,提示仍需加强对CSFV流行及遗传变异的持续监测,为猪瘟的诊断及有效防控奠定基础。

In order to investigate the prevalence and genetic variation of classical swine fever virus(CSFV)from 2018 to 2020 in Fujian province,1464 samples of whole blood,lungs,spleens and lymph nodes were collected from clinical sick pigs and detected by RT-nPCR.Then the E0 gene were cloned from the CSFV-positive samples and sequenced for genetic analysis.The results showed that 1.9%samples(19/1464)were CSFV-positive and E0 gene was amplifi ed and sequenced from 13 samples.The homology of E0 gene sequences of these 13 strains ranged from 82.2%to 99.7%,among which 11 strains shared 99.0%to 99.9%homology with the representative strain HCLV of subtype 1.1 and 94.1%to 95.0%with the Shimen strain.Additionally,one strain had 98.2%nucleotide homology with the 2.1c reference strain HNSD-20121and another strain had 99.6%nucleotide homology with CSFV/JPN/2018 subtype 2.1d strain.Genetic evolution analysis showed that 10 strains were in the same branch with HCLV,C-ZJ-2008,Shimen and Brescia strains,belonging to subtype 1.1,one strain that belonged to 2.1c subtype was in the same branch with HNSD-2012and another strain was located in the same branch with CSFV/JPN/2018of2.1d subtype.Amino acid sequence analysis showed that 13 strains were highly conserved at RNase active sites as compared with the representative strains such as HCLV.However,2 strains that belonged to subtype 2.1,had a G→E mutation at the 35th non-critical amino acid residue.These results showed that the CSFV in Fujian province existed in a low prevalence but highly genetic diversity,suggesting a necessity to continuously monitor CSFV genetic variation.