Development of Epitope-Targeted SARS-CoV-2 Vaccines

目前急需一种针对SARS-CoV2的疫苗。我们开发了一种基于RNA噬菌体如MS2、PP7、AP205和Qß的病毒样颗粒（vlp）的疫苗平台技术。当多肽和蛋白抗原在这些生物纳米颗粒上多价显示时，它们获得了高水平的免疫原性。它们对几乎任何显示的抗原都能产生高滴度和长寿命的抗体反应。此外，VLP平台具有快速响应潜力，可以快速应对新出现的威胁。在这里，我们描述了一种展示SARS-CoV2表位的方法，并测试了它们在小鼠中引发中和抗体和保护性抗体的能力。我们的方法包括三个具体目标：在Aim 1中，我们将鉴定SARS-CoV2的候选疫苗表位，并通过在VLPs上展示赋予它们高免疫原性。该病毒与SARS-CoV1具有足够的序列和结构同源性，使我们能够根据对其中和抗体靶点的了解推断可能的中和表位。因此，我们描述了刺突蛋白表位的展示和优化策略，我们预测将引发抗体，分别抑制病毒进入的两个基本步骤-受体结合和病毒细胞融合。在Aim 2中，我们将用候选VLPs免疫小鼠，并使用ELISA定量产生的抗体反应，测试血清与重组刺突蛋白和代表所选表位的合成肽的反应。在Aim 3中，将通过培养细胞中的斑块减少中和试验来测试血清的中和活性。随后，我们将给小鼠接种人类ACE2 （SARS-CoV2受体）转基因疫苗，并测试其抵抗SARS-CoV2感染的能力。

A vaccine against SARS-CoV2 is badly needed. We have developed a vaccine platform technology based on virus-like particles (VLPs) of RNA phages like MS2, PP7, AP205 and Qß. When displayed multivalently on these bionanoparticles, peptide and protein antigens acquire a high level of immunogenicity. They elicit high titer and long-lived antibody responses to virtually any displayed antigen. Moreover, the VLP platform has rapid response potential to quickly counter emerging threats. Here we describe an approach to the display of SARS-CoV2 epitopes, and tests of their ability to elicit neutralizing and protective antibodies in mice. Our approach consists of three specific aims: In Aim 1, we will Identify candidate vaccine epitopes for SARS-CoV2 and endow them with high immunogenicity by displaying them on VLPs. This virus shares sufficient sequence and structural homology with SARS-CoV1 to allow us to infer likely neutralizing epitopes from knowledge of the targets of its neutralizing antibodies. Accordingly, we describe strategies for display and optimization of spike protein epitopes we predict will elicit antibodies that will separately inhibit two essential steps in virus entry - receptor binding and virus-cell fusion. In Aim 2, we will immunize mice with candidate VLPs and will use ELISA to quantify the resulting antibody responses, testing the reaction of sera with recombinant spike protein and with synthetic peptides representing the chosen epitopes. In Aim 3, the neutralization activity of sera will be tested by plaque reduction neutralization tests in cultured cells. Subsequently, we will vaccinate mice transgenic for human ACE2 (the SARS-CoV2 receptor) and test their abilities to resist the effects of SARS-CoV2 infection.