Viral Vectored COVID-19 Vaccines in a Guinea Pig Perinatal Infection Model

摘要 COVID-19疫情对全球公共卫生产生了深远影响。在120，000，000个病例中 据记录，全球范围内，美国已发生超过3000万例病例，其中COVID> 530，000例 死亡至今。美国在控制这一流行病方面取得了相当大的进展， 三种有效的疫苗和许多其他的免疫策略目前正在临床前研究和临床试验中。 审判一个正在形成的共识是，有效的疫苗将需要对病毒编码的刺突（S） 蛋白质，特别是其受体结合结构域（RBD）。然而，关于最佳方案的不确定性仍然存在。 表达平台，以及对疫苗接种引起的不良反应的担忧，包括 担心潜在的抗体依赖性感染增强。另一个主要问题是， 疫苗介导的对妊娠患者和胎儿/新生儿的保护。虽然先天性和 SARS-CoV-2感染的围产期传播已有记录， 尽管越来越多地描述了怀孕期间的免疫接种，但没有制定怀孕期间的免疫接种战略。 为了帮助为COVID-19疾病的未来疫苗战略提供信息和指导，我们将解决以下领域的问题： 使用SARS-CoV-2疫苗接种豚鼠模型的知识缺乏。我们的计划是验证假设 关于使用皮钦德病毒（PICV）载体的优化COVID-19疫苗策略。PICV是一种有包膜的RNA 沙粒病毒科中的一种病毒，目前尚不知道它会在人类或大多数动物中引起疾病。我们有 开发了一种基于PICV的病毒载体rP 18 tri，并证明它是一种安全、有效和通用的疫苗 载体，其激发平衡的抗体和T细胞应答。我们有初步数据显示一部小说 基于rP 18 tris的SARS-CoV-2 S RBD结构域疫苗可诱导特异性抗体，包括中和抗体， 抗体，在老鼠身上。在目标1中，我们将测试这种PICV载体疫苗（和其他疫苗） 具有改进的抗原设计）将在豚鼠中证明免疫原性， 图4示出了与MPLS佐剂化的RBD蛋白疫苗相比的免疫应答。我们将比较粘膜，皮下 和肌内免疫途径，比较ELISA和中和滴度。我们还将包括 粘膜读数，包括伊加应答，并将检验PICV载体与免疫应答相关的假设。 具有增强的IFN-γ ELISPOT应答（与含佐剂的RBD疫苗相比）。在目标2中，我们将研究 新生豚鼠早期免疫后疫苗安全性和经胎盘抗体转移 妊娠，比较PICV载体和亚单位RBD疫苗在母鼠至新生儿抗体转移模型。 我们将检查新生幼仔的血清，以检验病毒中和抗体穿过 胎盘这些实验与人类健康有很高的相关性，并将为未来的研究奠定基础。 在豚鼠妊娠模型中进行的SARS-CoV-2攻击研究反过来可以帮助阐明 疫苗策略，以控制妇女和婴儿的先天性和围产期获得性COVID-19疾病。

Abstract The COVID-19 pandemic has had a profound, global impact on public health. Of the 120,000,000 cases documented world-wide, over 30 million cases have occurred in the Unites States, with >530,000 COVID deaths to date. Considerable progress in control of the pandemic has been realized in the USA by licensure of three effective vaccines, and many additional immunization strategies are now in preclinical study and clinical trials. An emerging consensus is that an effective vaccine will require responses to the viral-encoded spike (S) protein, in particular, its receptor-binding domain (RBD). However, uncertainties remain about the optimal expression platform(s), as well as concerns for untoward effects conferred by vaccination, including the concern of potential antibody-dependent enhancement of infection. Another major issue is the need for vaccine-mediated protection of the pregnant patient and the fetus/neonate. Although congenital and perinatal transmission of SARS-CoV-2 infection has been documented, and serious COVID-19 disease in children is increasingly described, no strategy for immunization during pregnancy has been forthcoming. To help inform and direct future vaccine strategies for COVID-19 disease, we will address these areas of knowledge deficiency using a guinea pig model of SARS-CoV-2 vaccination. Our plan is to test hypotheses about optimized COVID-19 vaccine strategies using a Pichinde virus (PICV) vector. PICV is an enveloped RNA virus within the Arenavirus family and is not known to cause disease in humans or most animals. We have developed a PICV-based viral vector rP18tri and demonstrated it as a safe, effective, and versatile vaccine vector that elicits a balanced antibody and T cell response. We have preliminary data showing that a novel rP18tri-based SARS-CoV-2 S RBD domain vaccine can induce specific antibodies, including neutralizing antibodies, in mice. In Aim 1, we will test the hypothesis that this PICV-vectored vaccine (and other vaccines with improved antigen design) will demonstrate immunogenicity in guinea pigs, with enhanced immune responses compared to an MPL-adjuvanted RBD protein vaccine. We will compare mucosal, subcutaneous and intramuscular routes of immunization, comparing ELISA and neutralization titers. We will also include mucosal read-outs, including IgA responses, and will test the hypothesis that the PICV vector is associated with enhanced IFN-γ ELISPOT responses (compared to adjuvanted RBD vaccine). In Aim 2, we will examine vaccine safety and transplacental antibody transfer in neonatal guinea pigs following immunization in early pregnancy, comparing PICV vectored and subunit RBD vaccines in a dam-to-newborn antibody transfer model. We will examine serum from newborn pups to test the hypothesis that virus-neutralizing antibodies cross the placenta. These experiments have high relevance to human health, and will lay the groundwork for future SARS-CoV-2 challenge studies in the guinea pig pregnancy model that, in turn, can help clarify the optimal vaccine strategies to control congenital and perinatally-acquired COVID-19 disease in women and infants.