2018年中国部分地区猪瘟病毒2.1d亚型新流行株的基因组特征分析

为了解中国猪瘟病毒（classical swine fever virus，CSFV）的分子流行病学及遗传变异情况，本研究应用RT-PCR方法对2018年采集自河南、河北、山东、黑龙江和辽宁5个省份的350份疑似CSFV感染的病料进行E2和NS5B基因扩增，并对PCR产物进行测序和序列分析。结果显示，350份样品中21份为CSFV阳性，共获得14株CSFV的E2基因序列和7株CSFV的部分NS5B基因序列。E2全基因、NS5B部分基因序列分析表明，21份阳性样品均属于近年来在中国流行的CSFV 2.1d亚型，且新发现的2.1d亚型CSFV与中国较早2.1d亚型CSFV毒株间同源性差异不大，新发现的2.1d亚型CSFV分离株在E2基因的6个氨基酸（R³¹、S³⁴、W¹⁸²、K²⁰⁵、K³⁰³、A³³¹）上具有相同的分子特征，E2蛋白中15个位点上的半胱氨酸均未发生变异。韩国2.1d亚型CSFV在E2蛋白上具有3个独特的氨基酸（N⁹⁷、K¹⁵⁹、R²⁰⁵）特征，并且发现了韩国毒株YC11WB可能作为2.1b和2.1d亚型CSFV过渡毒株的证据，流行于中国和韩国的2.1d亚型CSFV可能分别来自于本国早期2.1b亚型CSFV的衍化。本研究证实，2018年中国及周边国家CSFV较为活跃，且流行毒株依然以2.1d亚型为主，为中国科学防控CSFV提供了依据。

Genomic Characteristics of 2.1d Subtype Epidemic Strain of Classical Swine Fever in China in 2018

In order to investigate the molecular epidemiology and genetic variation of classical swine fever virus (CSFV) in China,this study used the RT-PCR method to amplify E2 and NS5B genes of 350 samples suspected of CSFV infection that collected from Henan,Hebei,Shandong,Heilongjiang and Liaoning provinces in 2018,and the PCR products were sequenced and analyzed.The results showed that 21 of 350 samples were positive for CSFV detection and a total of 14 CSFV E2 gene sequences and 7 partial CSFV NS5B gene sequences were obtained.The complete E2 and partial NS5B gene sequences analysis showed that the 21 positive samples belonged to the 2.1d subtype CSFV that domestic epidemic in recent years.It found that there was no difference in homology between the newly 2.1d subtype CSFV and the earlier 2.1d subtype strains.These new 2.1d subtype CSFV isolates had the same molecular characteristics on the 6 amino acids (R³¹,S³⁴,W¹⁸²,K²⁰⁵,K³⁰³,A³³¹) of E2 gene,and 15 cysteines of E2 protein had no variation.The 2.1d subtype CSFV isolated in South Korean had three unique amino acids (N⁹⁷,K¹⁵⁹,R²⁰⁵) of E2 protein.The Korean strain YC11WB was an intermediate strain between 2.1b and 2.1d subtype CSFV,and the 2.1d subtype CSFV being prevalent in China and South Korea might be derived from the earlier domestic 2.1b subtype CSFV,respectively.This study confirmed that the relatively active and epidemic CSFV strains were still 2.1d subtype in China and neighboring countries in 2018,which providing a basis for scientific prevention and control of CSFV in China.