RESUMO
Objective:To analyze the molecular characteristics of Echovirus 11 (Echo11) strains isolated in Xiangyang, Hubei Province from 2016 to 2017 based on the sequences of VP1 gene.Methods:Rectal and throat swab specimens were collected from children with hand, foot and mouth disease (HFMD) in Xiangyang from 2016 to 2017. Echo11 strains were detected by real-time reverse transcriptase PCR (RT-PCR) and isolated after cultured in human rhabdosarcoma (RD) cells. The VP1 regions of Echo11 strains isolated from RD cells and the whole genomes of three representative Echo11 strains were amplified by conventional RT-PCR and the sequences were analyzed. DNAStar7.0 (MegAlign) and MEGA6.0 (Data) were used to analyze the homology and mutation sites in nucleotide and amino acid sequences. Neighbor-joining method was used to construct phylogenetic trees. Recombination analysis was performed with SimPlot software (BootScanning).Results:A total of 11 Echo11 strains were isolated from 3 494 HFMD cases, accounting for 0.31%. They were highly homologous in the VP1 gene. These strains shared 98.4%-100.0% homology in nucleotide sequences and 98.3%-100.0% homology in amino acid sequences. The homology between the 11 Echo11 strains and the prototype strain (Echo11/Gregory, X80059) was 73.9%-74.8% in nucleotide sequences and 87.7%-88.7% in amino acid sequences. All of the Echo11 strains circulating in Xiangyang were classified into lineage D, having a similarity to the strains circulating in some regions of mainland China since 2013. In multiple regions of the genome, the Echo11 strains isolated in Xiangyang were highly similar to the Henan Echo1 strains in 2010 and the Hubei Echo6 strains in 2015, suggesting there was recombination within the genome of Echo11 strains in Xiangyang.Conclusions:The Echo11 strains circulating in Xiangyang from 2016 to 2017 belonged to lineage D and were recombinant strains.