ABSTRACT
Objective In order to investigate etiology and molecular-epidemiological characteristics of enterovirus associated encephalitis (EAE) in Zhejiang,2008-2012.Method Cerebrospinal fluid and stool specimens were collected from suspected EAE patients,who were admitted to our hospitals.RD and Hep-2 cell lines were used to isolate enterovirus (EV).Serotypes of these EV isolates were identified through neutralization test by using serotype specific anti-sera.VP 1 genes of these isolates were sequenced,compared and used for the construction of phylogenetic tree.Results 127 (20.6％) human enterovirus (HEV) strains were isolated from 616 samples,which were collected from 610 patients.Serotypes of these EV isolates,including 60 coxsackievirus (CV),and 67 Echovirus (E) appeared to be CVA9,CVB1,CVB3-5,E3,E4,E6,E9,El4,E25 and E30,respectively.Predominant EV serotypes on EAE from 2008 to 2012 were seen as CVB3,CVB5,E6,E30 and E30,respectively.The full length of VP1 genes from different EV isolates was between 834 and 918 nucleotides.The VP1 gene similarities between these isolates and the reference strains were from 76.7％ to 85.0％ (nucleotides level) and 91.1％ to 97.9％ (amino acids level).The VP1 genes from E6 serotype isolates appeared most diverged,reaching 20.4％ (nucleotides level) attd 4.8％ (amino acids level).Based on the generated phylogenetic tree,all the EV isolates were fallen on the same branch of HEV-B,and the isolates in the same serotype formed one sub-branch,suggesting there existed geographical and temporal effects.E6 isolates diverged into two branchlets.Conclusion EVs from HEV-B were the etiologic agents for EAE in Zhejiang province from 2008 to 2012.All these EV isolates showed 12 serotypes,with predominant isolates varied every year.E30 was determined as the most dominant serotype while serotype E6 diverged into two sub-genetypes.