宁夏2010年肠道病毒71型进化分析

Genetic evolution of entervirus 71 isolated in Ningxia in 2010

目的分析2010年宁夏回族自治区手足口病(HFMD)患者中肠道病毒71型(Enterovirus 71,EV71)分离株基因特征。方法收集宁夏2010年手足口病患者粪便,咽拭子和疱疹液标本,进行病毒分离培养和Real-time RT-PCR检测后,对鉴定为EV71毒株的VP1编码区进行核苷酸序列测定分析。结果共收集各类标本994份,分离获得EV71 225株,对所有EV71毒株的VP1编码区基因进行序列测定,选择其中53株进行序列分析。宁夏分离株与A、B、C型基因型代表株核苷酸同源性分别为80.0%～81.5%、82.4%～84.7%和87.2%～99.1%;氨基酸同源性分别为93.9%～94.3%、96.3%～97.6%和97.6%～100%,与C4a亚型同源性最高为95.6%～99.1%,在系统发生树上,这53株毒株与C4基因型代表株聚为一簇,属于C4亚型中的C4a分支,而且提示至少存在4条病毒传播链。结论 2010年EV71的C4a亚型在宁夏有较广泛的流行,是宁夏流行的绝对优势基因亚型,其流行存在多条传播链。

Objective To analyze the genetic characteristics of EV71 strains isolated from HFMD cases in Ningxia in 2010. Methods In 2010, totally specimens including the stool, throat swab and vesicle samples were collected from Ningxia. Enterovirus iso- lation was performed in RD cell line from all the specimens. EV71 isolates were identified by specific real - time RT - PCR from the pos- itive cultures, and sequences of complete EVT1 VP1 encoding region were determined for farther analyses. Results Totally 225 EV71 strains were isolated and identified from 994 specimens in this study. And complete VP1 sequences of 225 EV71 strains were deter- mined, and genetic analyses of 53 in 225 strains were performed. It was showed that the nucleotide identity of 53 Ningxia strains with the representatives of A, B and C genotypes were 80.0% -81.5%, 82.4% ~ 84.7% and 87.2% ~ 99.1%, the amino acid identity were 93.9% ~ 94.3% , 96.3% ~ 97.6% and 97.6% ~ 100% , respectively. Data from sequence analysis showed that Ningxia strains shared 95.6 ~ 99.1 in VP1 region and were the most homoioplastic with C4a subgenotype. Phylogenetic tree analysis revealed that 53 stains were clustered with reference stains of subgenotype C4 and the Ningxia EV71 isolates were belonged to subgenotype CAa. And it revealed that these strains belonged to at least 4 viral transmission chains in the phylogenetic tree. Conclusion EVT1 of subgenotype C4a has spread widely in Ningxia in 2009, which is absolutely predominant type and exited several viral transmission chains in Ningxia in 2010.