2019—2021年江苏地区PCV3感染情况调查及其Cap基因的遗传演化分析

Investigation of PCV3 infection and genetic evolution of Cap gene in Jiangsu Province,2019-2021

为了解猪圆环病毒3型(PCV3)在江苏地区规模化猪场的感染及病毒演化情况,对2019—2021年收集的113份临床组织样品进行Cap基因的检测,应用DNAStar和MEGA软件对获得的序列进行遗传演化分析。结果显示:PCV3样品阳性率为37.17%(42/113),猪场阳性率为73.91%(17/23)。对29个阳性样品的PCR产物直接测序,显示核苷酸序列高度同源,同源性为97.3%~100.0%。挑取其中的12个阳性样品,扩增Cap全长序列,连接至pMD19-T平末端载体后测序,显示12条序列的核苷酸同源性为97.5%~99.8%,与国内外其他PCV3毒株Cap基因的同源性为97.0%~100%。遗传演化分析显示,3条序列与国内外PCV3亚群3a的毒株处于一个大的分支,6条序列属于3b,3条序列形成独立的分支(3c)。推导编码氨基酸后对24和27位氨基酸位点进行分析,1条序列为A^(24)K^(27),2条序列为A^(24)R^(27),9条序列为V^(24)K^(27)。本试验丰富了江苏地区PCV3感染的分子流行病学数据,为该地区PCV3感染的综合防控提供了科学依据。

To investigate the infection and virus evolution of porcine circovirus type 3(PCV3)in large-scale pig farms in Jiangsu Province,Cap was amplified and sequenced from 113 clinical tissue samples collected from 2019 to 2021,and the analysis of genetic evolution was performed using DNAStar and MEGA software.The positive rate was 37.17%(42/113)in samples and 73.91%(17/23)in farms.Direct sequencing of PCR products of 29 positive samples showed that the nucleotide sequence was highly homologous,ranging from 97.3%to 100.0%.Twelve positive samples were selected to amplify the complete length of Cap gene,which were cloned to the pMD19-T vector and sequenced.The results showed that the nucleotide homology of the 12 sequences was 97.5%-99.8%with each other,and 97.0%-100%with referenced strains.Genetic evolution analysis showed that 3 sequences were clustered to a large clade with PCV3a,6 sequences belonged to 3b,and 3 sequences formed an independent clade(3c).The deduced amino acids of 24 and 27 position were analyzed,including 1 sequence of A^(24)K^(27),2 sequences of A^(24)R^(27),and 9 sequences of 2 V^(24)K^(27).This present study enriched the molecular epidemiological data of PCV3 in Jiangsu Province,and provided a scientific basis for the prevention and control of PCV3 in this area.