Whole genome sequence analysis of 17 enterovirus 71 strains isolated from children with hand,foot and mouth disease in Guizhou province / 中国小儿急救医学

ABSTRACT

Objective To inquire into the molecular epidemiology of enterovirus 71 ( EV71 ) in our region by analyzing the whole genome characteristics and genetic evolution of EV 71 strains isolated from Guizhou area. Methods The throat swabs samples of hospitalized children with hand,foot and mouth disease in Guizhou province from 2013 to 2015 were collected,the virus nucleic acid were extracted,then the whole genome of virus were piecewise amplified by reverse transcription polymerase chain reaction( RT-PCR) and sequenced. Sequencing results were edited and spliced by DNAMAN8. 0 software,then the viral genome se-quences were compared with genome sequences of other EV71 strains in the genebank by Blastn,the phyloge-netic tree was constructed by the Neighbor-Joining method in MEGA5. 2 software. Results The whole ge-nome sequences of 17 EV71 strains were successfully isolated and amplified,the whole genome length of 17 EV71 isolates was 7405 base pair,encoded about 2193 amino acids. The 17 isolates were divided into ten species of amino acid sequences by 12 differences of amino acid among the strains,different sequences and clinical types had not shown regularity and correlation. The nucleotide homology in VP1 region,5′untranslat-ed region(5′UTR) and 3′untranslated region (3′UTR) were high among 17 EV71 isolates. The results that the whole genome of 17 EV71 isolates was compared with representative strains of EV71 A,B,C genotype and coxsakievirus A 16 ( CA16) showed that 17 EV71 isolates had higher homology with EV71 C4a sub-type,95. 3%-98. 1%,and the lowest homology with CA16. The phylogenetic tree was constructed based on nucleotide sequence of the whole genome,VP1 region and 5′untranslated region of 17 isolates showed that the 17 isolates were clustered into one cluster,and were clustered in the same branch with C4a isoforms,the phy-logenetic relationships among different regions were different. Conclusion The popular genotype of EV71 strains in Guizhou area for 2013-2015 was C4a subtype,consistenting with the genotype of popular EV71 in other regions of China. EV71 strains hasn′t the antigen transformation and input of a new subtype temporari-ly,but exist nucleotide and amino acid changes,so need be chronically and dynamically monitored. There is no correlation between the amino acid sequence difference of 17 EV71 isolates and the state of an illness.