Preclinical Development of GV-MVA-VLP Vaccines Against COVID-19

项目总结 SARS-CoV-2以前所未有的速度和规模引发了一场致命的全球大流行。一种安全有效的 迫切需要疫苗来控制这种新的病原体。为了满足这一需求，GeoVax正在利用其 独特的GV-MVA-VLPTM平台和先进的抗原设计，可开发多种候选疫苗 新冠肺炎。在新冠肺炎疫苗中是独一无二的，GeoVax候选疫苗是专门为提供 对SARS-CoV-2的高度保护性免疫，同时避免抗体依赖增强(ADE)和 免疫病理学有可能使疫苗不仅无效，而且实际上是危险的。在……里面 除了确定最终的候选疫苗外，这里提出的工作还将产生科学数据 这些对整个新冠肺炎疫苗开发领域非常有价值，在测试我们独特的 疫苗将决定我们方法的应用是否能够克服ADE和免疫病理学 困扰SARS疫苗的风险。在具体目标1下，我们将完成GEO-CM02的建造 通过GEO-CM04候选疫苗。然后我们将测试这些候选者以证明抗原的表达， 可制造性，VLP的形成，以及在旨在模拟这些条件下的遗传稳定性 制造，将证明每种疫苗构造作为全面候选疫苗的适宜性 制作。最后，我们将生产足够数量的每种疫苗，以使计划中的动物研究 并将疫苗运送给我们在德克萨斯大学医学分校的合作者。在……下面 特定目的2，然后我们将在转基因人的小鼠中进行免疫原性和有效性研究 血管紧张素转换酶2(HACE2)。HACE2转基因小鼠模型是一种严谨的动物模型。 为SARS开发的，非常适合测试人类冠状病毒。我们将为动物接种疫苗，样本 分析动物的免疫反应，用SARS-CoV-2攻击动物，并对动物进行监测 挑战后疾病临床体征的发展。在具体目标3下，我们将分析来自 在hACE2小鼠实验中评价我们的免疫原性、有效性和安全性(ADE和免疫病理学) 候选疫苗。免疫原性分析将包括通过ELISA法进行结合抗体(Bab)、中和 抗体(NAB)采用血清中和试验，抗体依赖的细胞毒性(ADCC)采用细胞为基础 通过细胞内细胞因子筛选(ICS)检测T细胞应答。疗效分析将包括病毒载量 以及与未接种疫苗的对照组相比的组织病理学。我们还将分析血清和组织样本以确定 ADE和免疫病理学的证据，以检验我们的疫苗将避免这些相关风险的假设 用SARS疫苗。所有这些参数将有助于筛选出最具免疫原性(诱导广谱抗体)的 和T细胞反应)和安全性(挑战时缺乏ADE和免疫病理学)是进一步的候选疫苗 在非人类灵长类动物和第一阶段人体试验中进行测试。

PROJECT SUMMARY With unprecedented speed and scale, SARS-CoV-2 has caused a deadly global pandemic. A safe and effective vaccine to control this new pathogen is desperately needed. To address this need, GeoVax is leveraging its unique GV-MVA-VLPTM platform and advanced antigen design to develop multiple vaccine candidates against COVID-19. Unique among COVID-19 vaccines, the GeoVax candidates are specifically designed to provide highly protective immunity against SARS-CoV-2 while avoiding antibody-dependent enhancement (ADE) and immunopathology that have the potential to render vaccines not only ineffective but actually dangerous. In addition to the identification of the final vaccine candidate, the work proposed here will generate scientific data that are extremely valuable to the overall field of COVID-19 vaccine development, in that testing of our unique vaccines will determine whether application of our approach is able to overcome the ADE and immunopathology risks that plagued SARS vaccines. Under Specific Aim 1, we will complete the construction of GEO-CM02 through GEO-CM04 vaccine candidates. We will then test these candidates to demonstrate antigen expression, manufacturability, formation of VLPs, and genetic stability under conditions designed to simulate those in manufacturing, which will demonstrate the suitability of each vaccine construct as a candidate for full-scale production. Finally, we will produce adequate amount of each vaccine to enable the animal studies planned in Specific Aim 2 and ship the vaccines to our collaborators at the University of Texas Medical Branch. Under Specific Aim 2, we will then perform an immunogenicity and efficacy study in mice transgenic for human angiotensin converting enzyme 2 (hACE2). The hACE2 transgenic mouse model is a rigorous animal model developed for SARS that is well suited for testing of human coronaviruses. We will immunize animals, sample the animals for analysis of immune responses, challenge the animals with SARS-CoV-2, and monitor the animals post-challenge for development of clinical signs of disease. Under Specific Aim 3, we will analyze samples from the hACE2 mouse study to assess the immunogenicity, efficacy and safety (ADE and immunopathology) of our vaccine candidates. Immunogenicity analyses will include binding antibody (BAb) by ELISA, neutralizing antibody (NAb) by serum neutralization assay, antibody-dependent cellular cytotoxicity (ADCC) by cell-based assay, and T cell responses by intracellular cytokine screening (ICS). Efficacy analyses will include viral load and histopathology relative to unvaccinated controls. We will also analyze serum and tissue samples for evidence of ADE and immunopathology to test the hypothesis that our vaccines will avoid these risks associated with SARS vaccines. All these parameters will help to down select the most immunogenic (inducing broad Ab and T cell responses) and safe (lack of ADE and immunopathology upon challenge) vaccine candidate for further testing in non-human primates and Phase 1 human trials.