Genetic characteristics analyses of the VP1 gene in coxsackievirus A16 isolates from Kunming in 2015
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摘要: 目的 研究昆明市2015-2016年手足口病患儿肠道病毒分子流行病学及探讨柯萨奇病毒A组16型(coxsackievirus A16,CVA16)VP1基因遗传变异与其时间和空间分布模式的相关性。方法 采集患儿的咽拭子和肛拭子样本,采用逆转录聚合酶链式反应分子鉴定法分别扩增肠道病毒71型和CVA16的VP1基因全长,随机选取2015年9份CVA16阳性样本进行测序并与数据库参考株构建系统进化树。对不同年份来源的CVA16病毒株间遗传距离与分离年份时间进行相关性和回归分析,并分析不同地理群体间的遗传距离与地理距离的相关性(Mantel检测)。结果 采样年度中大多数患儿为CVA16感染(咽拭子和肛拭子检出率分别为29.41%和15.69%),其与肠道病毒71型感染的比率分别为2.5 ∶1和2.0 ∶1。VP1基因系统进化分析显示9株CVA16昆明分离株均属于B基因型B1b亚型,且进一步划分成两个亚簇;种系进化及统计学分析显示VP1基因变异与时间推移和地理距离均具有正相关关系(均有P<0.05)。结论 2015年昆明市9株CVA16分离株为新生成的变异毒株,提示CVA16在昆明存在一定的地域流行特点。Abstract: Objective To study the molecular epidemiology of enterovirus associated with children hand-foot-mouth disease (HFMD) in Kunming from 2015 to 2016 and to explore the correlation between the genetic variation and spatial-temporal distribution pattern of coxsackievirus (CVA16) VP1 gene. Methods Throat swabs and rectal swabs were collected from children included in this study. Reverse transcription polymerase chain reaction was conducted to amplify the full-length VP1 gene of enterovirus 71 and CVA16. We randomly selected 9 CVA16 positive amplicons in 2015 for sequencing and these sequences were used to construct phylogenetic trees with relevant reference sequences from database. Correlation and regression analyses between genetic distances and the isolating times of CVA16 strains were performed. Mantel test between genetic distances and the geographical distances among geographical populations was also carried out. Results Most of the children were infected by CVA16 (the detection rate of throat swabs and rectal swabs were 29.41% and 15.69% respectively). The ratio of CVA 16 infection rate to enterovirus 71 infection rate was 2.5:1 and 2.0:1. Phylogenetic analyses of the VP1 gene proved that all the 9 CVA16 Kunming isolates belonged to genotype B, subgenotype B1b, and it can be further divided into two sub clusters. Phylogenetic and statistical analyses revealed a significant positive correlation between the genetic variation of CVA16 virus and both of the passage of time and geographical distance(all P<0.05). Conclusions The above results demonstrated that the 9 CVA16 isolates from Kunming, Yunnan Province, China in 2015, belonged to new mutant strains, suggesting its unique epidemic characteristic in Kunming city.
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