山东省环境污水和脑炎病例中埃可病毒6型的监测和关联

Surveillance and genetic characteristics of echovirus 6 strains isolated from environmental sewage and aseptic encephalitis cases

目的 探索山东省2014年急性脑膜炎/脑炎症候群（acute meningitis/encephalitis syn-drome,AMES）病例和2013—2014年环境污水监测中埃可病毒（echovirus,E）6型的基因特征及其关联.方法 对2014年的AMES病例标本和2013—2014年的环境监测标本进行肠道病毒（enterovir-us,EV）分离,阳性分离物采用分子生物学方法鉴定型别,并对E-6 VP1区序列进行同源性和系统进化学分析.结果 2013年AMES病例中未检出E-6,2014年分离到47株E-6,占EV分离株的29.56%.环境污水监测结果显示E-6从2013年夏季开始频繁出现并一直持续到2014年底,2013年分离到40株E-6,占总EV分离株的7.87%;2014年分离到139株E-6,占总分离株的26.18%.系统进化树分析表明本研究分离株属于A、C两个基因簇,各簇之内的环境和AMES分离株之间有密切的亲缘关系.在A基因簇中,2014年AMES分离株之间的核苷酸同源性是98.3%-100%,2013—2014年环境分离株之间的同源性是96.6%-100%,二者之间为97.1%-100%,C基因簇的以上核苷酸同源性分析结果分别是100%、98.7%-100%和99.1%-100%.结论 2014年山东省发生了两条E-6传播链导致的病毒性脑炎的流行;在E-6相关的病毒性脑炎流行之前,通过环境监测敏感地监测到E-6在本地的潜在流行,证明环境监测具有对相关疾病的早期预警能力.

Objective To analyze the genetic characteristics of echovirus 6 （ E-6） strains isolated from patients with acute meningitis/encephalitis syndrome （ AMES） in 2014 and sewage samples in 2013—2014 in Shandong province and to investigate their correlations.Methods Enterovirus strains were isolated from cerebrospinal fluid, stool and throat swab samples collected from 940 cases of AMES and 96 sewage samples used for environmental surveillance.The positive isolates were identified by molecular typing meth-od.Homologous and phylogenetic analyses based on the VP1 sequences of E-6 isolates were performed.Re-sults Altogether 47 E-6 strains were isolated from patients with AMES in 2014, accounting for 29.56%of all isolated enteroviruses （ EVs） strains.No E-6 strains were isolated from AMES cases in 2013.Data of the environmental surveillance showed that E-6 virus strains had been frequently detected in sewage samples since the summer of 2013 to the end of 2014.In total, 40 E-6 virus strains were isolated （7.87% of total isolated EVs strains） in 2013 and 139 E-6 virus strains （26.18%） in 2014.Phylogenetic analysis indicated that the E-6 isolates recruited in this study belonged to clusters A and C with high intracluster sequence iden-tities between AMES and environmental isolates.The nucleotide identities were 98.3%-100% among cluster A E-6 virus strains isolated from AMES cases in 2014 and 96.6%-100% among cluster A E-6 virus environ-mental isolates during the surveillance year 2013—2014.The cluster A E-6 virus strains shared 97.1%-100% nucleotide identities between the AMES and environmental isolates.For cluster C E-6 virus strains, the nucleotide identities were 100%, 98.7%-100% and 99.1%-100%, respectively.Conclusion The epidemic of viral encephalitis in Shandong province in 2014 was associated the transmission of two lineages of E-6 virus.Environmental surveillance revealed the potential epidemic of E-6 virus even before the epidemic of viral encephalitis in Shandong province, indicating the possibility of using environmental surveillance for early warning of related diseases.