Objective: To study the gene characterization of enterovirus 71 (EV71) virus strains isolated from clinical specimens of children with hand-foot-and-mouth disease (HFMD) in Zhejiang province.
Methods: Virus were isolated from clinical samples including stool, throat swab and vesicle from patients with HFMD. The EV71 isolates were identified by microneutralization assay and reverse transcriptase PCR (RT-PCR) with specific primer pair for VP1 genes of EV71. Complete VP1 gene sequences (891 nucleotides) for recent 6 EV71 isolates were determined and compared with that of A, B, C genotype reference EV71 strains and 11 EV71 China isolates available from GeneBank by homogeneity and phylogenetic tree analyses.
Results: 9 strains of EV were isolated from 14 clinical specimens. Data from microneutralization and RT-PCR results indicated that all the strains belong to EV71. The nucleotide and amino acid homogeneity of these 6 Zhejiang strains with the representative isolates of A and B genotypes were 82.9%-85.5% and 94.9%-98.0% respectively; with the representative isolates of C were 89.2%-94.1% and 97.0%-99.0% respectively. There were 91.0%-92.2%, 90.2%-90.3%, 89.2%-89.5%, 96.7%-96.9% nucleotide, homology with representative strains of C1, C2, C3,C4 subgenotypes of EV71. The nucleotide homogeneity of these 6 EV71 isolated strains with 9 previously isolated Chinese strains appeared to be 93.8%-97.1%. These 6 EV71 isolated strains were within genotype C subgenogroup C4 in the phylogenetic tree.
Conclusion: The recently identified EV71 isolates in Zhejiang province belonged to subgenogroup C4.