Molecular Basis of Dengue Virus Neutralization by Human Antibodies

描述(申请人提供)：登革热是一种新出现的由蚊子传播的人类病毒感染。感染者产生有效和持久的抗体(Abs)，中和同源登革病毒(DENV)血清型。矛盾的是，抗体还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DENV的结合和功能特性。对病原体的体液免疫反应来自长寿浆细胞(LLPC)和记忆B细胞(MBC)池，LLPC有助于循环抗体，记忆B细胞(MBC)池在再次接触病原体时被激活。虽然已知DENV感染可刺激强大的LLPC和MBC反应，但来源于这两个区段的抗体的特异性尚未被详细描述。基于本课题组和其他人的最新发现，我们建议检验这样一种假设，即通过紧密堆积在病毒表面的包膜(E)蛋白分子产生的新表位是人DENV血清型特异性中和抗体反应的主要靶点。接触初次DENV感染的人会产生长期的血清型特异性中和抗体反应，而继发感染会导致血清型交叉中和反应。我们认为，二次感染优先激活表达与两个或更多血清型高亲和力并能够交叉中和血清型的抗体的体细胞突变的MBCs。我们提出了三个特定的目标来表征初次感染(目标1和2)和继发感染(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，因为它将使一个主要集中在E蛋白亚基上的B细胞表位的领域重新定位，以考虑病毒组装后产生的新的结构特征和表位。这里提出的这些研究直接关系到开发简单的分析方法来预测领先的登革热候选疫苗的表现，也与开发安全有效的下一代登革热疫苗有关。。

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. .