两株西藏CV-B3的全基因组特征及溯源分析

Genetic Characteristics of Two CV-B3 Sequences from Tibet,China,and Analysis of Trace

肠道病毒是一种常见的引起婴幼儿急性传染病的病毒,它引起的疾病包括急性弛缓性麻痹、手足口病、无菌性脑膜炎和心肌炎等,甚至死亡。柯萨奇病毒B组3型(CV-B3)是引起急性心肌炎常见的病原体之一,并且也经常引起无菌性脑膜炎的暴发。本研究对在西藏自治区分离的两株CV-B3进行全基因组序列测定和分析,结果表明与原型株相比,核苷酸相似性仅为80.6%。通过系统进化分析,中国大陆流行的CV-B3可以分为三个传播链(lineage1～3),从20世纪lineage1便开始在中国传播,现在倾向于消失,目前lineage2和lineage3替代lineage1成为主要的传播链,现在在中国大陆地区传播。本研究的两株CV-B3也被发现可能与江苏省的一株CV-B5(2009-148-4株)在P3编码区发生了重组,且最大似然进化树的拓扑结构的改变也印证这一重组事件的可能性。频繁的重组活动为肠道病毒的进化提供了原始的基因材料,这也成为肠道病毒频繁暴发的原因之一。本研究分析了西藏两株CV-B3的全基因组序列特征,阐明了CV-B3在中国大陆的传播模式,为CV-B3的防控工作提供了基础资料。

Enterovirus,which caused acute infections in infants,is a common virus that caused a series of contagious diseases,including hand,foot and mouth disease(HFMD),myocarditis,aseptic meningitis,acute flaccid paralysis(AFP)and death.The CV-B3 was a major pathogen of acute myocarditis,and caused large outbreaks of aseptic meningitis in China and worldwide.Two CV-B3 strains were isolated from Tibet and sequenced in this study.The nucleotide similarity between prototype and these CV-B3 sequences was only 80.6%.The maximum likelihood phylogenetic tree showed that CV-B3 strains in the mainland of China were divided into three lineages.Lineage1 emerged in the last century and tended to have disappeared.While lineage 2 and lineage 3 were two major lineages of transmission,and had spread to the mainland of China.At the P3 coding region,the CV-B3 strains recombined with a possible donor of CV-B5(2009-148-4 strain)isolated from Jiangsu Province.The maximum likelihood phylogenetic tree of each fragment supported this recombination event.Frequent recombination events offered the raw materials for evolution of enteroviruses,thereby contributing to outbreaks of CV-B3 infection.Our study illustrates the entire genomic characteristics of two Tibet CV-B3 strains and the transmission patterns in the mainland of China,which offer the basic data needed for prevention of enterovirus-based diseases.