The gene characterizationof VP1 and 2A of Enterovirus type 71

Abstract

：Objective To detect VP1and 2A genes of Enterovirus type 71 (EV71) isolated from clinical specimens of patientswith light or heavy symptoms and analyze the homogeneity and phylogenetic tree. MethodsFifty clinical specimens of children with hand-foot-and-mouth disease ( HFMD) were dealedwith, which were tested by RT-PCR assay with specific primer pairs for EV71. EV71 isolatesfrom patients with light or heavy clinical symptoms were tested by RT-PCR assay with twospecific primer pairs for VP1 and 2A genes of EV71 respectively. All of the PCR productswere sequenced and compared with that of previously isolated EV71 isolates available fromGenBank by homogeneity and phylogenetic tree analyses. Results The RT-PCR resultsindicated that 30 isolates were EV71, 13 of 30 isolates were from clinical specimens ofpatients with light symptoms of hand-foot and mouth, the other were from clinicalspecimens of patients with heavy symptoms of complications. VP1 genes and 2A genes of 10EV71 isolated strains including 5 light strains and 5 heavy strains were sequenced andcompared with that of previously isolated 5 EV71 Chinese isolates available from GenBank(fuyangEU703814.1, xi_anHM003207. 1, shandongEU753418.1, shenzhenFJ607337.1,henanGU366191. 1) by homogeneity and phylogenetic tree analyses. The homogeneity of VP1and 2A genes of the 10 EV71 isolated strains and 5 previously isolated strains werebetween 94.7% -99.4% and 93.6% -99.3% respectively, with the representative isolates of Aand B genotypes was between 81.0%-84. 6% and 78. 4%-82. 2% respectively. The datasuggested that all of the 10 Chinese isolates belong to EV71 genotype C. There were only87.8% -90.2% homology among these 10 strains and the representative strains of C1, C2, C3sub-genotypes of EV71 but 96. 8% -99.6% homology among these 10 strains and therepresentative strains of C4 sub-genotypes of EV71, this suggested that these 10 Chineseisolates composed the C4 sub-genotype, of the C genotype, that formed a single branch inthe phylogenetic tree. Conclusion EV71 of sub-genotype C4 distributed in Mainland China,and VP1 genes have close genetic relationship between isolated strains. There is noobvious difference in 2A genes between clinical specimens of patients with light or heavysymptoms by homogeneity and phylogenetic tree analyses.