广东省一株新型肠道病毒EV-B83型的全基因组序列进化分析及重组分析

Molecular Evolution and Recombination of an Enterovirus B83 Isolated in Guangdong Province,China

本研究对2001年广东省急性弛缓性麻痹(Acute flaccid paralysis,AFP)病例中分离到的一株肠道病毒AFP341GD-CHN2001株进行了高通量测序后,获取该全基因组序列,经鉴定该毒株为EV-B83。为了解该广东省首株EV-B83分离株的全基因组特征及其重组特点,本研究对AFP341GD-CHN2001毒株通过最大似然法构建系统进化树,利用bootscanning分析该毒株与其它型别肠道病毒的重组位点,最后根据该重组位点分区段构建系统进化树,进一步验证重组分析结果。全长VP1序列构建的分子进化树表明,AFP341GD-CHN2001毒株与EV-B83原型株及柬埔寨SEP025KH2012分离株形成一簇;初步构建P1、P2、P3编码区序列系统进化树,提示该分离株在其分子进化中可能存在基因重组,而bootscanning分析表明非结构蛋白编码区是其发生基因重组的区域。根据bootscanning分析的断裂点对该毒株的全基因组序列分成3段构建系统进化树,该系统进化分析结果进一步明确该分离株于2B、2C、3D非结构编码区存在型间重组,与AFP341GD-CHN2001发生重组的毒株为CV-A9分离株NSW-V20AU2008、CV-B2分离株NSW-V53AU2010以及CV-B3分离株SSMJL-CHN2006。当前GenBank数据库中仅有来自美国以及中国云南的两株EV-B83全基因组序列,缺乏对该基因型的分子进化特征描述,本研究中的AFP341GD-CHN2001毒株为广东省首株EV-B83分离株,扩展了EV-B83数据信息,为今后EV-B83的研究提供了基础性资料。

In recent years,novel enteroviruses(EVs) have been isolated increasingly from patients and the environment,which indicates the potential for their epidemic among populations. A complete genome was obtained by high-throughput sequencing of an enterovirus AFP341GD-CHN2001 strain isolated from a patient with acute flaccid paralysis in 2001,and it was identified as EV-B83. It is a rarely reported serotype and only two complete genome sequences of EV-B83 strains are available in GenBank,which were isolated in Yunnan Province,China and the USA,respectively. To describe the complete genome characteristics and recombination traits of EV-B83 strain AFP341GD-CHN2001,phylogenetic trees were constructed by the maximum likelihood method,and bootscanning analyses were implemented to confirm the recombination events and recognize the recombination breakpoints. Finally,based on the position of the breakpoints,we made several partitions of alignment and used each of them to construct a phylogenetic tree to verify the results of recombination analyses. The phylogenetic tree based on the VP1 region showed the Guangdong strain AFP341GD-CHN2001 clustered with the EV-B83 prototype strain and Cambodia strain SEP025KH2012.Preliminary phylogenetic trees based on P1,P2 and P3 regions as well as bootscanning analyses indicated some recombination events had occurred within the non-structural coding regions of Guangdong strain AFP341GD-CHN2001. Phylogenetic trees based on three partitions of alignment determined by breakpoints confirmed recombination events between AFP341GD-CHN2001 and the NSW-V20AU2008,NSW-V53AU2010 and SSMJL-CHN2006 strain,which took place in 2B,2C and 3D three non-structural coding regions.