2010年浙江省部分地区急性出血性结膜炎暴发疫情病原学研究

Study on the Pathological and Molecular Characteristics of AHC Epidemic in Zhejiang Province in 2010

为查明引起2010年浙江省急性出血性结膜炎(AHC)暴发疫情的病因,并对病原进行分子溯源。本研究采用荧光RT-PCR方法直接从患者眼拭子样本中检测肠道病毒(EV)和柯萨奇病毒A24变异株(CA24v)核酸;用Hep-2细胞分离病毒,对阳性分离物提取病毒核酸后进行VP1全基因和3C蛋白酶区(3C)扩增和测序,同源性与进化分析。结果13份眼拭子样本中EV和CA24v核酸均阳性8份,分离到CA24v6株。选取4株病毒测序,获得VP1全长均为915个核苷酸(nt),3C区全长495nt,VP1和3C区均没有nt插入和缺失。2010年浙江4株CA24v分离株之间在3C区和VP1区核苷酸和氨基酸(aa)高度同源,2010年浙江CA24v分离株与原型株EH24/70在3C区的nt和aa同源性分别为85.2%～85.8%和96.2%～96.7%,与2002～2008年浙江、云南和广东CA24v株的同源性分别为93.4%～96.2%和96.7%～99.3%;浙江2010年CA24v株在3C区进化树的GⅣ基因亚型C4分枝上(GⅣ-C4),在VP1基因进化树的人类肠道病毒C组(EV-C)CA24v分枝上。研究表明引起2010年浙江省急性出血性结膜炎暴发流行的病原为CA24v,GⅣ基因亚型,与引起2002～2008年浙江AHC流行的CA24v株(GⅣ)具有密切的亲缘关系,推测CA24v病毒自2002年以来一直在本地低强度循环,2010年又导致了浙江AHC的暴发。

To identify and trace the pathogen of acute hemorrhagic conjunctivitis （AHC） epidemic in Zhejiang Province in 2010. Viral nucleic acid of Enterovirus （EV） and Coxsackievirus A24 variant （CA24v） were directly detected by real-time RT-PCR from the conjunctival swab collected from suspected patients. The virus was isolated from the swab samples using Hep-2 cell. The viral RNAs were extracted from the i- solated viruses and followed by RT-PCR to amplify VP1 gene and 3C protease region（3C）. The amplified fragments were sequenced and phylogenetic trees were also constructed. Eight out of 13 swab samples from suspected patients were both positive for EV and CA24v RNA （61.5%）, 6 CA24v strains were isolated （46.2%）. The complete VP1 genes of CA24v in 4 sequenced virus strains were 915 nt in length and the complete 3C genes were 549 nt in length. All VP1 and 3C genes were confirmed without any insertion or deletion. The identity of nueleotide and amino acid in 3C between the 2010 isolated strains and the proto- type strain EH24/70 were 85.2%-85.8% and 96.2%-96.7%, and that between the 2010 Zhejiang strains and the Zhejiang,Yunnan and Guangdong CA24v strains isolated between 2007-2008 were 93.4%-93.8% and 96.7 %-97.3 %, respectively. The phylogenetic tree of 3C indicated that the isolated CA24v viruses of Zhejiang in 2010 located in the CA24v IVgenotype cluster 4 （GIV-C4） and all the VP1 genes located in the human Enterovirus C （EV-C） CA24v. These findings indicated that AHC epidemic in Zhejiang Province in 2010 was caused by CA24v GIV-C4 viruses and they most likely evolved from CA24v viruses circulating locally in external environment from 2002.