Sequence analysis of VP1 and VP4 genes of enterovirus 71 strains isolated from severe and mild hanD-foot-mouth disease cases in Shanghai, China, 2011 / 中华传染病杂志

ABSTRACT

Objective To analyze the VP1 and VP4 genetic region of enterovirus 71 (EV71)isolated from severe cases and mild cases with hanD-foot-mouth disease (HFMD) in Shanghai in 2011.Methods Five EV71 strains isolated from severe cases and five EV71 strains from mild cases in 2011 were included.Reverse transcription-polymerase chain reaction (RT-PCR) method was used to amplify and sequence the VP1 and VP4 genes of EV71,and then the sequencing results were compared with those of A,B,C genotype reference EV71 strains from GenBank by nucleotide alignment,amino acid alignment and phylogenetic tree analyses.Results The homogeneity between EV71 strains from severe cases and mild cases was 96.0％-98.1％ and 93.7％-99.5％ for VP1 and VP4 nucleotide sequences,respectively.The VP1 nucleotide sequences of 5 strains isolated from severe cases and 5 strains from mild cases in Shanghai shared 86.9％-98.2％ and 87.4％ 98.5％ identity with genotype C,respectively,while the homogeneity of VP4 nucleotide sequence was 85.5％-100.0％and 84.5％-99.5％,respectively.In addition,compared with the Fuyang EV71 strains (representative of C4 subtype),the strains from mild and severe cases shared homogeneity of 97.0％-98.2％ and 97.9％-98.5％ for VP1 gene,respectively,96.1％-100.0％ and 97.1％-99.5％ for VP4 gene,respectively.Among 3 strains isolated from severe cases,mutations at the residue 282 in the VP1 protein (N→S) and residue 7 in the VP4 protein (T→A) were discovered simultaneously.Conclusions The 10 EV71 strains isolated from severe and mild cases in Shanghai belong to subgenogroup C4.Among 3 strains isolated from severe cases,mutations at the residue 282 in the VP1 protein (N→S) and residue 7 in the VP4 protein(T→A) are discovered simultaneously.