Structural and functional basis of ultra potent CHKV neutralization by human mAbs

 描述(申请人提供)：基孔肯雅病毒(CHIKV)是一种重新出现的蚊媒甲型病毒，直接在人和蚊子之间循环，在全球范围内导致人类患上一种令人衰弱的发热性疾病。现在已经描述了新世界的本土传播，美洲至少19个国家爆发了疫情，在短短6个月内就有超过25万例病例。截至7月1日，已有29个州向ArboNet报告了从加勒比海返回美国的旅行者中出现的CHIKV疾病病例。由于其主要媒介之一白纹伊蚊的普遍分布，北美和南美洲流行的可能性很高。尽管有可能感染数百万人并导致疾病，但目前还没有针对CHIKV的特定治疗方法或疫苗。该项目的一个主要目标是确定具有广泛活性的超强中和人单抗的分子、遗传、免疫学和结构特征。其他目标包括确定这些超强中和单抗保护的机械相关性。在这些研究中，我们将阐明具有特殊抑制活性的抗病毒抗体如何在细胞培养和体内发挥作用。该方法将包括高效分离人类单抗，以及基于NextGen测序的创新抗体基因谱系研究。将测试几个假设，包括超强中和活性是由抗体(持续CHIKV感染导致的广泛突变)和抗原(与多个相邻包膜蛋白上的四元表位结合，并阻止对病毒进入或释放至关重要的结构转变)的特征产生的概念。虽然我们的重点是了解超强抗人单抗是如何以及为什么抑制CHIKV的，但这些研究可能与许多不同病毒的抗体中和的一般原理有关。 除了确定CHIKV抗体中和的分子和结构基础外，这些研究还将产生一组完全人源性的单抗，可以预防和治疗CHIKV在小鼠体内的感染和持久性，未来可能开发为一种可能的人类联合免疫疗法。该项目的研究虽然是针对CHIKV的，但可能会为未来基于抗体的和/或针对导致人类疾病的其他甲型病毒的疫苗努力提供信息。我们组建了一个独特的研究小组，其中包括一名人类抗体专家，一名在抗体-病毒相互作用方面经验丰富的分子病毒学家，以及两名在甲型病毒(包括CHIKV)方面具有特殊专业知识的有成就的结构生物学家，以进行这些研究。

 DESCRIPTION (provided by applicant): Chikungunya virus (CHIKV) is a re-emerging mosquito-borne alphavirus that cycles directly between humans and mosquitoes and causes a debilitating febrile illness in humans on a global scale. Autochthonous transmission in the New World now has been described, with outbreaks in at least 19 countries in the Americas and over a quarter million cases in just 6 months. CHIKV disease cases have been reported to ArboNET in travelers returning to the US from the Caribbean in 29 states, as of July 1. The potential for epidemics in North and South America is high due to the ubiquitous distribution of one of its primary vectors, Aedes albopictus. Despite the possibility for infecting and causing disease in millions, specific treatments or vaccines for CHIKV are not available. A primary goal of this project is to define the molecular, genetic, immunologic, and structural characteristics of ultra-potent neutralizing human mAbs with broad activity against all genotypes of CHIKV. Additional goals include defining the mechanistic correlates of protection by these ultra-potent neutralizing mAbs. In these studies, we will elucidate how antiviral Abs with exceptional inhibitory activity exert their action in cell culture and in vivo. The approach will include high efficiency isolationof human mAbs, coupled with innovative antibody gene repertoire studies based on nextgen sequencing. Several hypotheses will be tested, including the concept that ultra-potent neutralizing activity results from features of both the antibodies (extensive mutations due to persistent CHIKV infection) and the antigen (binding to quaternary epitopes on multiple adjacent envelope proteins and blocking structural transitions critical for virus entry or release). Althoug our focus is to understand how and why ultra-potent human mAbs inhibit CHIKV, the studies likely will be relevant to general principles of antibody neutralization of many different viruses. Beyond defining the molecular and structural basis of Ab neutralization of CHIKV, these studies will generate a group of fully human mAbs that can prevent and treat CHIKV infection and persistence in mice, which could be developed in the future as a possible combination immunotherapeutic for humans. Studies in this project, while targeted against CHIKV, likely will inform future Ab-based and/or vaccine efforts against other alphaviruses that cause human disease. We have assembled a unique group of investigators, including a human Ab expert, a molecular virologist with experience in Ab-virus interactions, and two accomplished structural biologists with specific expertise in alphaviruses, including CHIKV, to pursue these studies.