2021年南京市手足口病流行特征及柯萨奇A组4型VP1区基因特征分析

Epidemiological characteristics of hand-foot-mouth disease and gene characteristics of VP1 from CVA4 in Nanjing,2021

目的了解南京市手足口病(HFMD)流行特征,分析柯萨奇病毒A组(CVA)4型基因特征。方法收集2021年来自南京市12个区的监测样本,使用实时荧光定量PCR方法检测肠道病毒并分型,对排除CVA6、16、10型和肠道病毒(EV)71型阳性的其他未分型肠道病毒,用反转录·聚合酶链反应(RT-PCR)的方法扩增VP4-VP2区,双向测序确定基因型,最后巢式扩增CVA4型的VP1区,确定其基因亚型。结果2021年南京市手足口病呈季节性流行,不同月份之间的肠道病毒阳性率差异有统计学意义(χ^(2)=80.06,P<0.05)。易感人群为3~<6岁儿童,该年龄段阳性数占总阳性数的57.05%(178/312)。不同年龄段之间的肠道病毒阳性率差异有统计学意义(χ^(2)=73.70,P<0.05)。地区分布中,肠道病毒阳性率占前三位的依次是玄武区94.74%(18/19)、浦口区94.00%(47/50)和江北新区83.33%(65/78),不同地区肠道病毒阳性率差异有统计学意义(χ^(2)=177.42,P<0.05)。550份标本中,荧光定量PCR法检测肠道病毒阳性312份,主要型别为CVA6型,占总阳性数的83.01%(259/312),其次依次为CVA16型(21份)和CVA10型(5份),未分型肠道病毒27份。经VP4-VP2区测序得到CVA4型6份,对其VP1区扩增测序后获得目的片段。结论南京市2021年手足口病主要型别以CVA6型为主,与其他毒株(CVA16型、CVA4型、CVA10型等)共同循环流行;其中CVA4型毒株均属于C2亚型,未发现新的亚型,需持续监测。

Objective To investigate the epidemiological characteristics of hand-foot-mouth disease(HFMD)in Nanjing and to analyze the gene characteristics of coxasckievirus A(CVA)4.Methods Surveillance samples from 12 districts of Nanjing were collected.Reverse transcription-polymerase chain reaction(RT-PCR)was used to detect and the type of enterovirus.The untyped enterovirus VP4-VP2 region and CVA4 VP1 regions were amplified by RT-PCR.Results In 2021,HFMD was a seasonal epidemic in Nanjing,there was a statistically significant difference in the positive rate of enteroviruses between different months(χ^(2)=80.06,P<0.05).The susceptible population was children aged 3-<6 years old,accounting for 57.05%(178/312)of the total positive population.There was a statistically significant difference in the positive rate of enterovirus among different age groups(χ^(2)=73.70,P<0.05).In terms of regional distribution,the top three regions with positive rates of enteroviruses were Xuanwu District(94.74%,18/19),Pukou District(94.00%,47/50),and Jiangbei District(83.33%,65/78).There was a statistically significant difference in the positive rates of enteroviruses among different regions(χ^(2)=177.42,P<0.05).There were 312 positive samples out of 550 monitoring samples;the main type was CVA6,accounting for 83.01%(259/312),followed by CVA16 and CVA10,and 27 were untyped enterovirus.Six of untyped enterovirus were CVA4,belonging to C2 subtype.Conclusions The main type of HFMD in Nanjing in 2021 was CVA6,which circulated with other strains(CVA16,CVA4,CVA10,etc.).CVA4 strain belong to subtype C2,and no new subtype had been found;continuous monitoring of HFMD in Nanjing was required.