Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA.
Proc Natl Acad Sci U S A. 2012 May 8;109(19):7439-44. doi: 10.1073/pnas.1200566109. Epub 2012 Apr 12.
Dengue is a mosquito-borne flavivirus that is spreading at an unprecedented rate and has developed into a major health and economic burden in over 50 countries. Even though infected individuals develop potent and long-lasting serotype-specific neutralizing antibodies (Abs), the epitopes engaged by human neutralizing Abs have not been identified. Here, we demonstrate that the dengue virus (DENV)-specific serum Ab response in humans consists of a large fraction of cross-reactive, poorly neutralizing Abs and a small fraction of serotype-specific, potently inhibitory Abs. Although many mouse-generated, strongly neutralizing monoclonal antibodies (mAbs) recognize epitopes that are present on recombinant DENV envelope (E) proteins, unexpectedly, the majority of neutralizing Abs in human immune sera bound to intact virions but not to the ectodomain of purified soluble E proteins. These conclusions with polyclonal Abs were confirmed with newly generated human mAbs derived from DENV-immune individuals. Two of three strongly neutralizing human mAbs bound to E protein epitopes that were preserved on the virion but not on recombinant E (rE) protein. We propose that humans produce Abs that neutralize DENV infection by binding a complex, quaternary structure epitope that is expressed only when E proteins are assembled on a virus particle. Mapping studies indicate that this epitope has a footprint that spans adjacent E protein dimers and includes residues at the hinge between domains I and II of E protein. These results have significant implications for the DENV Ab and vaccine field.
登革热是一种由蚊子传播的黄病毒，其传播速度前所未有，已在 50 多个国家发展成为主要的健康和经济负担。尽管感染个体产生了强效且持久的血清型特异性中和抗体（Abs），但人类中和 Abs 结合的表位尚未确定。在这里，我们证明人类登革热病毒（DENV）特异性血清 Ab 反应由大量交叉反应、中和能力差的 Ab 和少量血清型特异性、强效抑制性 Ab 组成。尽管许多由小鼠产生的、具有强烈中和能力的单克隆抗体（mAbs）识别存在于重组 DENV 包膜（E）蛋白上的表位，但出乎意料的是，人类免疫血清中的大多数中和 Ab 结合完整病毒粒子，但不结合纯化可溶性 E 蛋白的外域。这些与多克隆 Ab 的结论在源自 DENV 免疫个体的新生成的人 mAbs 中得到了证实。三种强中和人 mAb 中的两种结合到存在于病毒粒子上但不存在于重组 E（rE）蛋白上的 E 蛋白表位。我们提出，人类产生的 Ab 通过结合仅在 E 蛋白组装在病毒颗粒上时表达的复杂、四级结构表位来中和 DENV 感染。映射研究表明，该表位的足迹跨越相邻的 E 蛋白二聚体，并包括 E 蛋白 I 域和 II 域之间铰链处的残基。这些结果对 DENV Ab 和疫苗领域具有重要意义。
