Identification and characterization of a cross-neutralization epitope of Enterovirus 71
Identification and characterization of a cross-neutralization epitope of Enterovirus 71
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DOI：
10.1016/j.vaccine.2011.04.010
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发表时间：
2011-06-10
期刊：
影响因子：
5.5
通讯作者：
Chong, Pele
中科院分区：
文献类型：
--
作者：
Liu, Chia-Chyi;Chou, Ai-Hsiang;Chong, Pele
儿童肠病毒71型（EV71）感染表现为皮疹，最常见的是手足口病（HFMD）。由于它可引起脊髓灰质炎等严重的神经系统并发症，EV71现在已成为亚洲重要的嗜神经病毒。EV71病毒已被证明由3种（A、B和C）基因型和许多亚基因型组成。虽然EV71疫苗的开发最近取得了有希望的临床前结果，但候选疫苗中抗原含量与保护性抗体反应水平之间的相关性尚未确定。EV71抗原的中和表位可作为疫苗效力的替代生物标志物。利用多肽ELISA、明胶配制的福尔马林灭活EV71病毒粒子疫苗免疫动物产生的抗血清、EV71特异性中和单克隆抗体（nMAb）和覆盖EV71病毒VP1、VP2和VP3全序列的153个重叠合成肽，我们筛选了免疫优势线性中和表位。合成肽VP2-28，对应于VP2的136 ~ 150残基，发现与nMAb MAB979结合并抑制其与EV71的结合，发现对不同基因型的EV71病毒具有交叉中和活性。此外，VP2-28仅能被福尔马林灭活EV71全病毒疫苗免疫家兔产生的抗血清识别，而不能被免疫小鼠和大鼠产生的抗血清识别。在表位定位过程中，在小鼠EV71基因型和菌株特异性线性中和表位VP1的残基211-220中鉴定出VP1-43。此外，基于以脊髓灰质炎病毒为模板进行分子建模的序列比对和结构预测分析，VP1-43和VP2-28表位在0.1 nm内平行运行，并在病毒衣壳中VP1和VP2的交界处形成峡谷边缘。在小鼠、大鼠和家兔的免疫原性研究中，疫苗制剂中定量测定的VP2-28表位单位的数量与中和效价的大小之间存在剂量依赖关系。VP2-28具有在EV71基因型中高度保守的氨基酸序列，不受福尔马林处理和长期储存的影响。因此，VP2-28可作为EV71候选疫苗效价检测的替代生物标志物。(C) 2011 Elsevier Ltd.版权所有。
Enterovirus 71 (EV71) infections in children manifest as exanthema and are most commonly known as hand-foot-and-mouth disease (HFMD). Because it can cause severe neurological complications like poliomyelitis, EV71 has now emerged as an important neurotropic virus in Asia. EV71 virus has been shown to consist of 3 (A, B and C) genotypes and many subgenotypes. Although EV71 vaccine development has recently yielded promising preclinical results, yet the correlation between the content of antigen(s) in vaccine candidates and the level of protective antibody responses is not established. The neutralization epitope(s) of EV71 antigens could be used as the surrogate biomarker of vaccine potency. Using peptide ELISA, antisera generated from animals immunized with formalin-inactivated EV71 virion vaccine formulated in alum, EV71-specific neutralizing monoclonal antibody (nMAb) and a panel of 153 overlapping synthetic peptides covering the entire sequences of VP1, VP2 and VP3 of EV71, we screened for immunodominant linear neutralization epitope(s). Synthetic peptide VP2-28, corresponding to residues 136-150 of VP2, was found to bind to and inhibit the binding to EV71 of nMAb MAB979 that was found to have cross-neutralizing activity against different genotypes of EV71 virus. In addition, VP2-28 was found to be recognized only by neutralizing antisera generated from rabbits immunized with the formalin-inactivated whole EV71 virion vaccine but not by antisera from immunized mice and rats. During the epitope mapping, a murine EV71 genotype- and strain-specific linear neutralization epitope VP1-43 was identified within residues 211-220 of VP1. Furthermore, based on sequence alignment and structure prediction analysis using poliovirus as the template for molecular modeling, the VP1-43 and VP2-28 epitopes were shown to run in parallel within 0.1 nm and form a rim of the canyon at the junction site of VP1 and VP2 in the viral capsid. In mouse, rat and rabbit immunogenicity studies, a dose-dependent relationship between the number of VP2-28 epitope units measured by a quantitative assay in vaccine preparations and the magnitude of neutralizing titers was demonstrated. VP2-28 has amino acid sequences that are highly conserved among EV71 genotypes, is not affected by formalin-treatment and long-term storage. Thus, VP2-28 could be used as the surrogate biomarker in the potency testing of candidate EV71 vaccines. (C) 2011 Elsevier Ltd. All rights reserved.