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

项目摘要 SARS-CoV-2以前所未有的速度和规模造成了致命的全球大流行。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，以开发多种候选疫苗， 新冠肺炎。在COVID-19疫苗中，GeoVax候选疫苗是专门设计的， 对SARS-CoV-2的高度保护性免疫，同时避免抗体依赖性增强（ADE）， 免疫病理学，有可能使疫苗不仅无效，但实际上是危险的。在 除了确定最终的候选疫苗外，这里提出的工作将产生科学数据 这对COVID-19疫苗开发的整个领域都非常有价值，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 SARS疫苗面临的风险在具体目标1下，我们将完成GEO-CM02的构建 GEO-CM04候选疫苗。然后我们将测试这些候选物以证明抗原表达， 可制造性，VLP的形成，以及在设计用于模拟 生产，这将证明每种疫苗构建体作为全规模候选疫苗的适用性。 生产最后，我们将生产足够数量的每种疫苗，以便计划在 具体目标2并将疫苗运送给我们在德克萨斯大学医学分支的合作者。下 具体目标2，我们将在转人基因小鼠中进行免疫原性和有效性研究 血管紧张素转换酶2（hACE 2）。hACE 2转基因小鼠模型是一种严格的动物模型 为SARS开发的，非常适合测试人类冠状病毒。我们会给动物免疫， 用于分析免疫应答的动物，用SARS-CoV-2攻击动物，并监测动物 攻毒后出现疾病临床体征。在具体目标3下，我们将分析来自 hACE2小鼠研究，以评估我们的免疫原性、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ELISA法测定的结合抗体（BAb）、中和 通过血清中和试验测定抗体（NAb），通过基于细胞的 通过细胞内细胞因子筛选（ICS）测定T细胞应答。疗效分析将包括病毒载量 和组织病理学。我们还将分析血清和组织样本， ADE和免疫病理学证据，以检验我们的疫苗将避免这些相关风险的假设 SARS疫苗所有这些参数将有助于向下选择最具免疫原性的（诱导广泛的Ab 和T细胞应答）和安全（攻击后缺乏ADE和免疫病理学）的疫苗候选物，用于进一步的免疫治疗。 在非人类灵长类动物和1期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.