Molecular Basis of Dengue Virus Neutralization by Human Antibodies

描述（由申请人提供）：登革热是一种新兴的蚊子传播的人类病毒感染。受感染的人产生有效和持久的抗体（Abs），可中和同源登革热病毒（DENV）血清型。矛盾的是，抗体也与病毒复制增强和更严重的疾病有关。尽管有证据表明抗体在登革热发病机制中很重要，但我们才刚刚开始了解人类抗体对登革热病毒反应的结合和功能特性。对病原体的体液免疫反应来源于长寿命浆细胞（llpc），它们有助于循环抗体和记忆B细胞（MBC）池，后者在再次暴露于病原体时被激活。虽然已知DENV感染会刺激LLPC和MBC反应，但从这两个区室衍生的抗体的特异性尚未得到详细表征。基于我们小组和其他人最近的发现，我们提出验证病毒表面包膜(E)蛋白分子紧密包装产生的新表位是人类DENV血清型特异性中和Ab反应的主要目标的假设。暴露于原发性DENV感染的人产生长期血清型特异性中和抗体反应，而继发性感染导致血清型交叉中和反应。我们提出，第二次感染优先激活表达抗体的体细胞突变MBCs，这些抗体与2种或更多血清型具有高亲和力，并且能够交叉中和血清型。我们提出了三个特定的目标来表征原发性感染（目标1和2）和继发性感染（目标3）后来自MBC和llpc的中和抗体。这项工作的影响将是深远的，因为它将改变一个主要关注E蛋白亚基上的B细胞表位的领域，以考虑病毒组装后产生的新结构特征和表位。这里提出的这些研究与开发预测主要登革热候选疫苗的性能的简单检测方法以及开发下一代安全有效的登革热疫苗直接相关。

DESCRIPTION (provided by applicant): Dengue is an emerging mosquito-borne viral infection of humans. Infected people develop potent and long lasting antibodies (Abs) that neutralize the homologous dengue virus (DENV) serotype. Paradoxically, Abs have also been implicated in enhanced viral replication and more severe disease. Despite the evidence that Abs are important in dengue pathogenesis, we are just beginning to learn about the binding and functional properties of the human Ab response to DENV. The humoral immune response to a pathogen is derived from long-lived plasma cells (LLPCs) that contribute to circulating Abs and a memory B cell (MBC) pool that is activated upon re-exposure to the pathogen. While it is known that DENV infection stimulates robust LLPC and MBC responses, specific properties of Abs derived from these two compartments have not been characterized in detail. Based on recent findings from our group and others, we propose to test the hypothesis that new epitopes created by close packing of envelope (E) protein molecules on the viral surface are the main target of the human DENV serotype-specific neutralizing Ab response. People exposed to primary DENV infections develop long-term serotype specific neutralizing Ab responses whereas secondary infections result in serotype cross neutralizing responses. We propose that second infections preferentially activate somatically mutated MBCs expressing Abs that bind with high affinity to 2 or more serotypes and are capable of cross neutralizing serotypes. We propose three specific aims to characterize neutralizing antibodies derived from MBC and LLPCs after primary infections (Aims 1 and 2) and secondary infections (Aim 3). The impact of this work will be far ranging as it will redirect a field that has mainly focused on B cell epitope on subunits of E protein to consider new structural features and epitopes created following viral assembly. These studies proposed here are directly relevant to developing simple assays to predict the performance of the leading dengue vaccine candidates and also for developing the next generation of safe and effective dengue vaccines. .