2012年天津市手足口病病原与分子流行病学分析

Etiology and molecular epidemiology of hand,foot,and mouth disease in Tianjin in 2012

目的对天津市2012年的手足口病病例进行病原学检测，并对引起HFMD流行的肠道EV71型（EV71）和柯萨奇A组16型（CVA16）病毒进行分子生物学特征分析。方法利用Real—time PCR检测HFMD疑似病例标本，用人横纹肌肉瘤（RD）细胞对Real—time PCR检测阳性的部分病例标本进行病毒分离。随机挑取9株EV71病毒分离株和8株CVA16病毒分离株，采用PCR扩增VPl全基因，并进行核苷酸序列和遗传进化分析。结果共检测HFMD疑似病例1829例，肠道病毒总阳性率为81．30％（1487／1829），其中EV71占39．88％，CVA16占38．33％，其他EV占21．79％。9株EV71分离株与C4亚型的C4a分支代表株的核苷酸序列同源性为97．3％～98．5％，均归属于C4a分支；8株CVA16分离株与B1亚型代表株的核苷酸序列同源性为92．9％～97．1％，其中7株属于B1b分支，1株属于B1a分支。结论导致天津市2012年HFMD流行的EV71为C4亚型中的C4a病毒株，CVA16为B1亚型的B1b病毒株。

Objective To analyze the pathogens responsible for hand, foot, and mouth disease （HFMD）, and the mo- lecular epidemiological characteristics of Enterovirus 71 （EV71） and Coxsackie virus A16 （CVA16） in Tianjin in 2012. Methods Clinical specimens from patients with HFMD were tested using real-time PCR. Use of rhabdomyosarcoma （RD） cells resulted in the isolation of EVT1 and CVA16 strains from some positive specimens. VP1 genes of the nine EVT1 and eight CVA16 isolates were amplified using RT-PCR. Sequencing and phylogenetic analysis were carried out using biology software. Results In total, 1 829 specimens were tested. Overall, specimens tested positive for enterovirus at a rate of 81.30% （1 487/1 829）. EVT1 accounted for 39. 880/00 of all positive specimens, CVA16 accounted for 38.33%, and other enteroviruses accounted for 21. 790%. Nine EVT1 isolates had the greatest similarity （97. 3%- 98.5%） to the representative strain of the C4a cluster of the C4 subtype. Eight CVA16 isolates had the greatest similarity （92.9 %- 97.1%） to the representative strain of the 131 subtype. Seven of eight isolates belonged to the Blb cluster, and the remaining isolate belonged to the Bla cluster. Conclusion The C4a strain of EVT1 and the Blb strain of CVA16 caused outbreaks of HFMD in Tianjin in 2012.