引起两起手足口病聚集性疫情的柯萨奇病毒A6的VP1基因特征及其分子流行病学研究

Comparative and molecular epidemical studies on VP1 gene characters of coxsackievirus A6 isolated from the two distinct outbreaks of HFMD epidemic

目的了解两起疫情的Cox A6的VP1基因特征的异同,研究其分子流行病学特征。方法测定其VP1基因全序列,用分析软件对VP1基因做适应性进化分析。结果从两起聚集性疫情中分离到的Cox A6分别属于2013年流行的2个流行亚群,其中1个亚群在氨基酸254位发生R→K的突变,该突变被推测是受正向选择作用的结果。而且两起聚集性病例的分枝分化时间分别是在2012年第3季度-第4季度和2012年第4季度-2013年第1季度。结论在本地区2013年流行的手足口肠道病毒Cox A6的2个主要的流行亚群的分化时间在2010年冬季-2011年春季,经过2年～3年的低流行期后目前在本地区进入高流行期,并在本市分别引起了两起手足口病聚集性疫情。

Objective To investigate the differences and similarity of the VP1 gene characters of coxsackievirus A6 isolated from the two distinct outbreaks of HFMD epidemic,and to investigate the molecular epidemic characters for the two outbreaks of HFMD epidemic. Methods The VP1 genes were sequenced,and the adapt evolution analyses were conducted using the current mainstream methods for molecular evolution analyses. Results The strains of coxsackievirus A6 isolated from the two distinct outbreaks of HFMD epidemic were inferred to belong to respectively two sub- groups which were prevalent in 2013,and the strains in one of the two sub- groups were proved to acquire a common mutation（ R → K） at site 254 of amino acid sequences,which was then inferred to be under positive selection. Moreover,the divergent times of the two clades corresponding to the distinct outbreaks were inferred to be during the third quarter to the fourth quarter of 2012 and during the fourth quarter of2012 to the first quarter of 2013. Conclusion This paper concluded that the divergent time of the two distinct sub- groups were ranged from winter in 2010 to spring in 2011,and through 2- 3 years of low- level epidemic,they become prevalent and hence separately triggered the two distinct outbreaks of HFMD epidemic in our city.