Molecular Basis of Dengue Virus Neutralization by Human Antibodies

描述（由申请人提供）：登革热是一种新出现的人类蚊媒病毒感染。感染者产生有效和持久的抗体（Ab），中和同源登革病毒（DENV）血清型。巧合的是，抗体也与增强的病毒复制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抗体对DENV的结合和功能特性。对病原体的体液免疫应答来源于有助于循环Ab的长寿命浆细胞（LLPC）和在再次暴露于病原体时被激活的记忆B细胞（MBC）库。虽然已知DENV感染刺激稳健的LLPC和MBC应答，但衍生自这两个区室的Ab的特异性性质尚未详细表征。基于我们小组和其他人的最新发现，我们建议测试以下假设：通过病毒表面上的包膜（E）蛋白分子的紧密包装产生的新表位是人DENV病毒型特异性中和Ab应答的主要靶标。暴露于原发DENV感染的人发展长期血清型特异性中和Ab应答，而继发感染导致血清型交叉中和应答。我们提出，第二次感染优先激活体细胞突变的MBC表达抗体，以高亲和力结合2个或更多个血清型，并能够交叉中和血清型。我们提出了三个具体目标，以表征原发性感染（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广泛的，因为它将重新定向一个领域，主要集中在B细胞表位的E蛋白亚基，以考虑新的结构特征和表位后产生的病毒组装。本文提出的这些研究与开发简单的检测方法直接相关，以预测领先的登革热候选疫苗的性能，并开发下一代安全有效的登革热疫苗。.

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. .