深圳市一起输入性登革热疫情的分子流行病学研究

摘 要：目的 对2007年深圳市报告的一起输入性疑似登革热病例查明病因。分离鉴定病原体，从分子水平分析分离株的生物学特征。方法 对疑似患者血清标本采用ELISA、胶体金免疫层析法和实时荧光定量PCR方法分别检测登革病毒IgM、IgG抗体和病毒核酸，并用C6/36细胞分离登革病毒。采用RT-PCR方法扩增病毒PrM/M-E基因后进行序列测定，并与不同国家和地区的登革毒株进行同源性比较和进化树分析。结果 从患者血清标本中检测到登革病毒IgM、IgG抗体和登革3型病毒核酸，并首次成功分离到登革3病毒，将其命名为DEN3-SZ0739。深圳市登革3型病毒分离株SZ0739与登革3型国际标准株H87株、国内外流行株80-2、GWL-25株在PrM/M-E基因上核苷酸同源性分别为94.1%、93.9%、96.9%，而与登革1、2、4型国际标准株HAWAII、NGC、H241同源性分别为66.1%、59.1%、58.2%。进化树显示SZ0739株与2007年新加坡分离株SGEHI(D3)0235Y07亲缘关系最近，在进化树的同一分支上，和1416株(India 1984)、1326株(Sri Lanka 1981)、1696株(Samoa 1986)等同属基因Ⅲ亚型。结论 从病原学、血清学和分子生物学特征上均证实该输入病例是由登革3型病毒引起，该毒株最有可能来源于新加坡。

Molecular epidemiological of an imported dengue fever in Shenzhen

To determine the etiology of an imported dengue fever case reported in Shenzhen city in 2007 and to isolate and identify the pathogen of dengue fever，the molecular characteristics of the isolated dengue virus strain were studied. The serum sample collected from the suspect dengue fever case was detected for IgM, IgG by ELISA, immunochromatography and dengue virus nucleic acid by real-time RT-PCR. The samples were further inoculated in C6/36 cells for virus isolation. PrM/M-E gene of isolated virus strain was amplified by RT-PCR and sequenced to construct homology comparison and phylogenetic tree of PrM/M-E gene of Shenzhen dengue virus with the strains isolated from other areas. Results found that IgM, IgG and RNA of type 3 dengue virus were detected in the serum sample and type 3 dengue virus named DEN3-SZ0739 was successfully isolated from the serum sample for the first time. The homology of nucleotide sequence of PrM/M-E gene of SZ0739 with standard type 3 dengue virus H87 strain, 80-2 strain,GWL-25 strain were 94.1％,93.9% and 96.9% respectively, but the homology with standard dengue virus 1,2,4 in the same fragment were 66.1％, 59.1% and 58.2% respectively. The phylogenetic tree indicated that SZ0739 had the greatest similarity with the SGEHI(D3)0235Y07 strain(Singapore 2007) and they lied in the same branch of the phylogenetic tree. The isolated dengue virus type 3 belonged to genotype Ⅲ with 1416 strain(India 1984),1326 strain(Sri Lanka 1981) and 1696 strain(Samoa 1986). The foundings indicate that virological, serological and molecular features showed that the imported case of dengue fever was caused by type 3 dengue virus and most likely from Singapore.