2009—2018年辽宁省急性弛缓性麻痹监测中肠道病毒A组71型VP1区基因特征分析

Genetic characteristics of VP1 region of enterovirus group A type 71 in surveillance of acute flaccid paralysis in Liaoning Province,China from 2009 to 2018

目的分析辽宁省2009—2018年急性弛缓性麻痹(acute flaccid paralysis,AFP)病例中人肠道病毒A组71型(EV-A71)VP1区的基因特征。方法对辽宁省2009—2018年AFP病例的粪便标本进行病毒分离,将分离到的非脊髓灰质炎肠道病毒(non-polio enterovirus,NPEV)进行RT-PCR,将阳性产物进行VP1区序列测定。用BioEdit软件对分离株VP1区序列与EV-A71 C4亚型的C4a分支及EV-A71原型株进行同源性比对;根据EV-A71 VP1编码区全长,采用Neighbor-Joining方法构建所获分离株及从GenBank下载的EV-A71各基因型及亚型代表株的进化树,并用Mega4.0软件分析。结果共检测1 044例AFP粪便标本,99例标本分离到NPEV,其中11例标本的分离株为EV-A71;此11株分离株VP1区核苷酸及氨基酸与C4亚型的C4a分支同源性分别为96.5%~98.3%和98.6%~99.3%;与EV-A71原型株同源性分别为81.1%~82.2%和93.6%~94.7%;11株EV-A71之间核苷酸及氨基酸同源性为95.5%~100%和98.6%~100%。进化树分析表明,辽宁省EV-A71分离株与C4亚型的C4a分支处于同一支。结论辽宁省11株EV-A71分离株为密切相关的一簇,来源于同一传播链,为C4亚型中的C4a进化分支。本文为辽宁省AFP监测提供了病原学依据。

Objective To analyze the genetic characteristics of VP1 region of human enterovirus group A type 71(EVA71)in patients with acute flaccid paralysis(AFP)Liaoning Province,China from 2009 to 2018. Methods Non-polio enterovirus(NPEV)was isolated from the fecal specimens of patients with AFP in Liaoning Province during 2009 ~ 2018 for amplification by RT-PCR,and the VP1 gene of PCR product was sequenced and compared with those of the clade C4 a of EV-A71 subtype C4 and EV-A71 prototype by using BioEdit software. According to the full-length of encoding region of VP1 of EV-A71,a phylogenetic tree of the isolates and the representative EV-A71 strains of various genotypes and subtypes from GenBank was constructed by Neighbor-Joining and analyzed by Mega 4. 0 software. Results A total of1 044 fecal specimens of patients with AFP were tested,of which 99 were positive for NPEV including 11 ones positive for EV-A71. The homologies of nucleotide(nt) and amino acid(aa) of VP1 regions of the 11 isolates were96. 5% ~ 98. 3% and 98. 6% ~ 99. 3% to those of clade C4 a of EV-A71 subtype C4,and 81. 1% ~ 82. 2% and93. 6% ~ 94. 7% to those of EVA71 prototype,respectively. However,the homologies of nt and aa of the 11 isolates were 95. 5% ~ 100% and 98. 6% ~ 100% respectively. Phylogenetic analysis showed that EV-A71 isolates from Liaoning Province was at the same branch of C4 a clade of subtype C4. Conclusion The 11 isolates of EV-A71 from Liaoning Province are closely related,which are derived from the same transmission chain and belong to the C4 a clade of subtype C4. This study provides a pathological basis for the monitoring of AFP in Liaoning Province.