[Genetic characterization of echovirus 6 isolated from meningitis and encephalitis cases in Shandong Province, China].

To analyze the genetic characteristics of echovirus 6 (E6) isolated from meningitis and encephalitis cases in Shandong Province, China, we collected cerebrospinal fluid samples from meningitis and encephalitis cases in Shandong Province from 2007 to 2012 for virus isolation. Viral RNAs were extracted from positive isolates, and complete VP1 coding regions were amplified by RT-PCR and sequenced. Homology comparison and phylogenetic analysis were performed. Six isolates were identified as E6 by microneutralization assay and molecular typing. The homology analysis showed that the six isolates had 78. 6%-99. 8% nucleotide and 95. 5%-100. 0% amino acid identities with each other, as well as 76. 9%-78. 4% nucleotide and 92. 3%-95. 1% amino acid identities with the prototype strain (D' Amori). The phylogenetic analysis based on the integrated VP1 sequences indicated that all Shandong E6 isolates could be separated into four clusters, designated as A, B, C, and D. The six E6 isolates belonged to clusters A, B, and D. Our study reveals high genetic differences between Shandong E6 isolates and suggests different transmission lineages of E6 co-circulated in Shandong Province.