2009年浙江省义乌市登革热暴发疫情实验诊断和病原分子溯源

目的 对2009年浙江省义乌市发生疑似登革热暴发疫情进行实验诊断和病原分子溯源.方法 对40份疑似患者的血清样本同时进行登革病毒抗体、病毒核酸检测和病毒分离.对分离毒株提取病毒核酸后用RT-PCR方法扩增E基因,进行核苷酸序列测定和同源性与进化分析.结果 40份血清样本中登革病毒IgM抗体阳性17份(42.5%),IgG抗体阳性4份(10.0%);核酸阳性34份(85.0%);分离到登革病毒3型(D3)28株(70.0%).选取13株D3分离株测序,E基因全长均为1479个核苷酸(nt),无插入或缺失突变,推导编码493个氨基酸(aa).13株浙江D3分离株之间E基因同源性为100.0%.浙江D3株与2004年沙特阿拉伯分离株(Sandi Arabia/2004)的同源性最高,nt和aa同源性分别为99.3%和100.0%;与原型株(D3/H87/1956)相比同源性分别为93.4%和97.4%;与1980年中国广西D3分离株在该区域的同源性分别为93.6%和97.4%.E基因进化树显示浙江D3分离株在GⅢ进化支上,与浙江株亲缘关系最近的毒株为沙特阿拉伯株,均在同一进化支上.结论 引起2009年浙江省义乌市登革热暴发疫情的病原是登革3型GⅢ亚型,该病毒最有可能来源于沙特阿拉伯.

Diagnosis of a dengue fever outbreak in Yiwu city, Zhejiang province in 2009 and its molecular tracing of the pathogen

Objective To determine a dengue fever outbreak in Yiwu city,Zhejiang Province in 2009 and to trace the origin of the pathogen. Methods The dengue virus IgM, IgG antibodies and viral nucleic acid were detected and virus was isolated using 40 serum samples from the suspected patients. The viral RNA of the isolated virus strains was extracted and the E gene was amplified by RT-PCR. The amplicons were sequenced and the phylogenetic and homological analyses were also constructed. Results Among 40 serum samples from dengue fever suspected patients, 17 were positive from for dengue IgM (42. 5%); 4 were IgG positive (10. 0%); 34 samples were dengue virus RNA positive (85.0%), 28 dengue virus type 3 (D3) strains were isolated (70. 0%). The complete coding region of envelope genes (E) from 13 D3 strains was all 1479 nt without any insertion or deletion,which encoded with 493 amino acids(aa). E gene from the 13 D3 strains from Zhejiang in 2009 (D3/ZJ/2009) was 100. 0% identical. The strain from Sandi Arabia shared the highest similarity with the D3 strain,99. 3% and 100. 0% of their E genes and deduced amino acids were identical,respectively,whereas they were 93.4% and 97.4% between D3/ZJ/2009 strain and its prototype strain (D3/H87/1956) ,and 93.6% and 97.4% between D3/ZJ/2009 and a D3 strain isolated in Guangxi Province in 1980. The phylogenetic tree of E genes also indicated that D3/ZJ/2009 had maximum similarity with the D3/Sandi Arabia/2004. They all belonged to the D3/G Ⅲ branch, which was originated from Indian Subcontinent. Conclusion The outbreak of dengue fever in Zhejiang in 2009 was caused by type 3 dengue virus Ⅲ genotype. The virus was most likely originated from Sandi Arabia.