Project 2: PanbetaCoV protein vaccine design

摘要-项目2 动物β冠状病毒（betaCoV），如引起SARS-CoV-1、MERS和现在的SARS的病毒- CoV-2是对人类健康的一个重大、持续的威胁。疫苗可以提供预先存在的免疫力 未来的人畜共患冠状病毒。目前有效的SARS-CoV-2疫苗的一个主要限制是， 可能只保护与武汉分离株几乎相同的SARS-CoV-2分离株， 疫苗。因此，世界仍然容易受到SARS-CoV-2突变逃逸变体的影响。 以及未来可能发生大流行的动物β冠状病毒溢出事件。疫苗开发 解决这一脆弱性的方法是迫切需要的。项目2将支持该计划的总体目标， 预防未来betaCoV大流行和SARS-CoV-2逃逸变体的疫苗， 设计疫苗免疫原，引发广泛中和抗体（bnAb）， 乙型冠状病毒的免疫力存在结构保守的中和表位 我们假设，能够引发针对这些蛋白质的广泛保护性抗体的疫苗， 网站可以开发。在初步研究中，我们已经分离出交叉反应的中和抗体， SARS-CoV-1或SARS-CoV-2感染或康复的人，并使用结构测定精确 定义其betaCoV bnAb表位。我们的疫苗设计策略包括使用计算和结构- 基于设计技术来开发优先呈现这些的免疫原， 鉴定的bnAb表位。每种免疫原设计都将展示在纳米颗粒的表面上，以增强免疫原的功能。 抗原亲合力和抗原运输到生发中心和滤泡树突细胞。我们展示了一个 我们使用多聚化SARS-CoV-2受体结合域（RBD）的策略的概念验证- 铁蛋白纳米颗粒诱导高滴度的抗体， 动物Sarbecoviruses（组2b）在免疫猕猴。在目标1中，我们将分离新的抗体以定义 另外的bnAb表位，并在betaCoV S蛋白表面上建立完整的区域谱， 能够将bnAb诱导为组2b和2c中的动物β CoV。在目标2中，我们将利用先进的 计算免疫原设计方法，以设计广泛中和的表位聚焦的免疫原。这些 免疫原具有固定在暴露中和表位的构象中的刺突蛋白， 被截短或重新表面化以去除不相关的、非中和的或betaCoV毒株特异性的亚基 中和表位，同时保留广泛中和表位。在目标3中，我们将免疫野生型小鼠， 与这些新的免疫原，并评估他们的能力，诱导人类betaCoV bnAb，可以保护 病毒攻击的动物。项目2将通过产生交叉反应中和抗体来影响该领域 这可以转化为治疗方法，阐明betaCoV刺突上新的广泛中和表位 蛋白质，并定义了引发保护性免疫的表位聚焦免疫原的设计原则 到贝塔冠状病毒

Abstract – Project 2 Animal betacoronaviruses (betaCoVs), such as those that gave rise to SARS-CoV-1, MERS, and now SARS- CoV-2, represent a significant, continuous threat to human health. Vaccines can provide pre-existing immunity to future zoonotic coronaviruses. A major limitation of the current effective vaccines to SARS-CoV-2 is that they likely will only protect SARS-CoV-2 isolates that are nearly identical to the Wuhan isolate used in the vaccines. Thus, the world remains vulnerable to SARS-CoV-2 mutational escape variants and from future animal betacoronavirus spillover events that have pandemic potential. Vaccine development that addresses this vulnerability is urgently needed. Project 2 will support this Program’s overall goal to develop vaccines that will prevent future betaCoV pandemics and SARS-CoV-2 escape variants by designing vaccine immunogens that elicit broadly neutralizing antibodies (bnAb) to provide protective immunity across the betaCoV genus. Structurally conserved neutralizing epitopes exist on betaCoV spike proteins, and we hypothesize that vaccines that elicit broadly protective antibodies to these sites can be developed. In preliminary studies, we have isolated cross-reactive neutralizing antibodies from SARS-CoV-1 or SARS-CoV-2-infected or recovered humans and used structural determination to precisely define their betaCoV bnAb epitopes. Our vaccine design strategy involves using computational and structural- based design techniques to develop immunogens that preferentially present these and additionally identified bnAb epitopes. Each immunogen design will be displayed on the surface of nanoparticles to enhance antigen avidity and antigen trafficking to germinal centers and follicular dendritic cells. We have demonstrated a proof-of-concept for our strategy using a multimerized SARS-CoV-2 receptor binding domain (RBD)- ferritin nanoparticle that induces high titers of antibodies that neutralize diverse human and animal Sarbecoviruses (group 2b) in immunized macaques. In Aim 1, we will isolate new antibodies to define additional bnAb epitopes and establish the full spectrum of regions on the surface of betaCoV S proteins that are capable of inducing bnAbs to animal betaCoVs in groups 2b and 2c. In Aim 2, we will utilize cutting-edge computational immunogen design methods to design broadly neutralizing epitope-focused immunogens. These immunogens have the spike protein fixed in conformations that expose neutralizing epitopes or are spike subunits that are truncated or resurfaced to remove irrelevant, non-neutralizing, or betaCoV strain-specific neutralizing epitopes while retaining broadly neutralizing epitopes. In Aim 3, we will immunize wild-type mice with these novel immunogens and evaluate their ability to induce human betaCoV bnAbs that can protect animals from viral challenge. Project 2 will impact the field by generating cross-reactive neutralizing antibodies that could be translated into therapeutics, elucidating new broadly neutralizing epitopes on the betaCoV spike protein, and defining the design principles for epitope-focused immunogens that elicit protective immunity to betaCoVs.