Structural Basis for Recognition of Human Enterovirus 71 by a Bivalent Broadly Neutralizing Monoclonal Antibody.
Structural Basis for Recognition of Human Enterovirus 71 by a Bivalent Broadly Neutralizing Monoclonal Antibody.
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二价广泛中和单克隆抗体识别人肠道病毒 71 型的结构基础
DOI：
10.1371/journal.ppat.1005454
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发表时间：
2016-03
期刊：
影响因子：
6.7
通讯作者：
Cong Y
中科院分区：
文献类型：
--
作者：
Ye X;Fan C;Ku Z;Zuo T;Kong L;Zhang C;Shi J;Liu Q;Chen T;Zhang Y;Jiang W;Zhang L;Huang Z;Cong Y
肠道病毒71型（EV 71）是导致手足口病的主要病原体，在幼儿中会引起严重的神经系统并发症，甚至死亡。我们最近发现了一种高效抗EV 71中和单克隆抗体，称为D5。在这里，我们研究了抗体D5识别EV 71的结构基础。通过冷冻电子显微镜（cryo-EM）单颗粒分析，全部以亚纳米分辨率重建与IgG或D5的Fab复合的EV 71颗粒的四个三维结构。最关键的EV 71成熟病毒粒子-Fab结构被解析到4.8 μ m的分辨率，这是迄今为止在病毒-抗体复合物的冷冻-EM研究中罕见的。这些结构揭示了D5抗体在成熟病毒体上跨二十面体2倍轴的二价结合模式，表明D5结合可能使病毒体刚性化以防止随后RNA释放所需的构象变化。此外，我们还确定了D5重链的互补决定区3（CDR 3）直接与EV 71的非常保守的VP 1 GH环相互作用，这是通过生物化学和病毒学实验验证的。我们进一步显示D5确实能够中和多种EV 71基因型和菌株。此外，D5可以在EV 71感染的小鼠模型中有效地赋予保护作用。由于保守的VP 1 GH环参与EV 71与其未包被受体（清道夫受体B类成员2（SCARB 2））的结合，D5的广泛中和能力可能归因于其抑制EV 71与SCARB 2的结合。总之，我们的结果阐明了广泛中和抗体D5结合和中和EV 71的结构基础，从而增强了我们对基于抗体的EV 71感染保护的理解。
Enterovirus 71 (EV71) is the main pathogen responsible for hand, foot and mouth disease with severe neurological complications and even death in young children. We have recently identified a highly potent anti-EV71 neutralizing monoclonal antibody, termed D5. Here we investigated the structural basis for recognition of EV71 by the antibody D5. Four three-dimensional structures of EV71 particles in complex with IgG or Fab of D5 were reconstructed by cryo-electron microscopy (cryo-EM) single particle analysis all at subnanometer resolutions. The most critical EV71 mature virion-Fab structure was resolved to a resolution of 4.8 Å, which is rare in cryo-EM studies of virus-antibody complex so far. The structures reveal a bivalent binding pattern of D5 antibody across the icosahedral 2-fold axis on mature virion, suggesting that D5 binding may rigidify virions to prevent their conformational changes required for subsequent RNA release. Moreover, we also identified that the complementary determining region 3 (CDR3) of D5 heavy chain directly interacts with the extremely conserved VP1 GH-loop of EV71, which was validated by biochemical and virological assays. We further showed that D5 is indeed able to neutralize a variety of EV71 genotypes and strains. Moreover, D5 could potently confer protection in a mouse model of EV71 infection. Since the conserved VP1 GH-loop is involved in EV71 binding with its uncoating receptor, the scavenger receptor class B, member 2 (SCARB2), the broadly neutralizing ability of D5 might attribute to its inhibition of EV71 from binding SCARB2. Altogether, our results elucidate the structural basis for the binding and neutralization of EV71 by the broadly neutralizing antibody D5, thereby enhancing our understanding of antibody-based protection against EV71 infection.