东莞市2014—2017年Ⅰ型登革病毒流行情况及E基因序列分析

Prevalence and E genes sequences analysis of dengue virus type 1 in Dongguan, 2014-2017

目的研究2014—2017年东莞市Ⅰ型登革病毒(DENV-1)流行情况,分析其可能的地域来源及基因特征。方法采用实时荧光PCR方法对2014—2017年东莞市疾病预防控制中心收到的登革热疫情样本进行核酸检测分型,阳性标本进行病毒分离及鉴定,扩增并测定部分分离株E基因序列,共得到8株DENV-1及其E基因序列,与Genebank中选取的世界各地DENV-1流行株及原型株进行参考对比,用DNASTAR软件进行核苷酸、氨基酸序列分析和同源性比较,用Mega4.0.2软件进行分子分型和系统进化树构建。结果 665份标本中DENV阳性251份,其中DENV-1阳性占90.0%。以9月、10月为发病高峰期,占86.7%;男女比例为0.92∶1,20～<70岁年龄组发病例数最多,占75.1%;DENV-1阳性本地病例以虎门、麻涌、南城、厚街和莞城五个镇街最多,占76.4%。序列比对显示,8株DENV-1的E基因序列核苷酸同源性为90.2%～99.6%,氨基酸同源性为96.4%～100.0%,与选取的近年世界各地流行株的核苷酸与氨基酸同源性分别为89.2%～100.0%和90.2%～100.0%。系统进化树分析显示,2014—2017年东莞8株DENV-1分离株与我国广州、深圳及新加坡、马来西亚等东南亚国家当年或往年DENV-1流行株同源性较高,分属基因Ⅰ、Ⅱ、Ⅴ型,但以基因Ⅰ、Ⅴ型为主。所有8株分离株与原型株进化距离较远。结论 2014—2017年东莞市登革病毒流行以DENV-1为主,流行基因亚型主要为基因Ⅰ型和基因Ⅴ型,流行方式为广深等周边地市及新加坡、马来西亚等东南亚各国输入病例引起的本地暴发流行。

Objective To study the prevalence of dengue virus type 1（DENV-1） in Dongguan during 2014 to 2017 and toexplore their possible origins and genetic characteristics. Methods The dengue virus nucleic acid of the dengue samplesduring 2014 to 2017 were detected by the real-time fluorescent RT-PCR method. The samples with positive dengue virusnucleic acid were amplified by RT-PCR, then part of the dengue strains E genes were sequenced, which were finished byGuangdong CDC. The 8 DENV-1 strains isolated from Dongguan and their E genes sequences were obtained. The phylogeneticanalysis was performed on the sequences obtained from the strains isolated from Dongguan and archived in GenBank for thoseDENV-1 strains from different regions including the international standard strains and by using the software DNASTAR andMEGA 4.0.2. Results Totally we received 665 samples, 251 samples were DENV positive,and the positive rate of DENV-1 was 90.0%. The incidence peaks were September and October, accounting for 86.7%; the male to female ratio of the incidencewas 0.92∶1, and the persons aged 20-70 years were the main population of the incidence of the disease, accounting for75.1% of the total number of cases. The largest region of DENV-1 positive indigenous cases was Humen, Machong, Nancheng,Houjie and Guancheng, accounting for 76.4%. The E gene sequence homogeneity of the 8 DENV-1 strains shared 90.2%-99.6% in nucleotide and 96.4%-100.0% in amino acid identity. Compared with the DENV-1 strains circulating in manyplaces around the world recently, the nucleotide sequences had 89.2%-100.0% similarity and the amino acid sequencesdeduced had 90.2%-100.0% similarity. The analysis of phylogenetic tree showed that the 8 strains isolated from Dongguanduring 2014-2017 had high homology with the strains isolated from Guangzhou and Shenzhen, also had high homology with thestrains isolated from Southeast Asian countries such as Singapore and Malaysia. Their genotypes were Ⅰ, Ⅱ or Ⅴ, which themain circulating genotypes were Ⅰ and Ⅴ. All the 8 strains isolated from Dongguan were far from the evolution of theprototype strain. Conclusion DENV-1 is the primary serotype circulating in Dongguan during 2014 to 2017, and the maincirculating genotypes are genotype Ⅰ and genotype Ⅴ. The outbreaks are originated from neighboring cities such as Guangzhou and Shenzhen and from Southeast Asian countries such as Singapore and Malaysia.