EV68中国分离株VP1基因高变区的特征分析

Characteristics of the VP1 gene hypervariable region in EV68 strains isolated in China

目的了解肠道病毒68（EV68）中国流行株VP1基因序列的特征。方法通过Clustal W法与多个国家EV68的VP1核酸序列进行比对，邻接法（Neighbor-Joining）构建系统进化树，与标准株Fermon相比，对该段区域编码的氨基酸序列进行分析。结果截至2015年底，中国已经分离出80株EV68。在进化上，突变主要发生在BC和DE环中，中国分离株VP1突变位置在83、89、91、94、96、97、98、102、109、139、141、142、143、144、147。并且大多数分离株VP1编码的氨基酸序列在140位置发生缺失。由进化树可以得出位于B、C进化分支的中国分离株分别为53株和21株。结论与标准株Fermon相比，发现在BC-loop和DE-loop发生了很大变化，然而BC-loop和DE-loop这两个区域与病毒的抗原性和毒力有关。中国EV68分离株位于B和C分支上。

Objective To investigate the characteristics of VP1 gene hypervariable region in hu- man enterovirus type 68 （HEV68） strains isolated in China. Methods Nucleotide sequences of the VP1 gene in the Chinese strains and strains isolated in other countries were aligned by using Clustal W in the MEGA6 program. The phylogenetic trees were constructed by using Neighbor-Joining （N J） method in the MEGA6 program. Sequence of the amino acids encoded by that region was analyzed by compared with that of the standard strain Fermon. Results A total of 80 strains of EV68 had been isolated in China by the end of 2015. Most of the mutations occurred in BC and DE loops. The mutation sites lied in the VP1 gene of Chinese isolates were at 83, 89, 91,94, 96, 97, 98, 102, 109, 139, 141, 142, 143, 144 and 147. Glycine was missing from most of the amino acid sequences encoded by the VP1 gene of Chinese strains. The phylogenetic analysis indicated that 53 and 21 EV68 strains isolated in China belonged to B and C clades, respectively. Conclusion Compared with the standard strain Fermon, the Chinese strains changed a lot in BC- loop and DE-loop, which were associated with the antigenicity and virulence of EV68. The EV6$ strains isolated in China belonged to B and C clades.