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

摘要 新冠肺炎疫情对全球公共卫生产生了深远的影响。在120,000,000起案件中 据记载，在世界范围内，超过3000万例病例发生在美国，有53万人感染新城疫 到目前为止的死亡人数。美国在控制大流行方面取得了相当大的进展，因为获得了 三种有效的疫苗和许多额外的免疫策略目前正在进行临床前研究和临床 审判。一个新出现的共识是，有效的疫苗需要对病毒编码的尖峰做出反应(S) 蛋白质，特别是它的受体结合域(RBD)。然而，关于最优方案的不确定性依然存在。 表达平台(S)，以及对疫苗接种带来的不良影响的担忧，包括 担心潜在的抗体依赖的感染增强。另一个主要问题是需要 疫苗对孕妇和胎儿/新生儿的保护。虽然先天和 SARS-CoV-2感染的围产期传播已有记录，严重的新冠肺炎病在 尽管对儿童的描述越来越多，但还没有即将出台的孕期免疫战略。 为了帮助告知和指导未来新冠肺炎疾病的疫苗战略，我们将解决以下方面 利用SARS-CoV-2疫苗接种豚鼠模型的知识缺失。我们的计划是检验假设 关于使用匹辛德病毒(PICV)载体优化新冠肺炎疫苗策略。PICV是一种有包膜的RNA 沙眼病毒属沙门氏菌属病毒，目前尚不知道会引起人类或大多数动物的疾病。我们有 开发了一种基于PICV的病毒载体rP18tri，并证明它是一种安全、有效和通用的疫苗 能够产生平衡的抗体和T细胞反应的载体。我们有初步数据显示，一部小说 基于rP18tri的SARS-CoV-2 S RBD区疫苗可诱导产生特异性抗体，包括中和 小鼠体内的抗体。在目标1中，我们将测试这种PICV载体疫苗(和其他疫苗)的假设 经过改进的抗原设计)将在豚鼠身上表现出免疫原性，免疫功能增强 与MPL佐剂RBD蛋白疫苗的反应进行比较。我们会比较粘膜、皮下 肌肉免疫途径，比较ELISA法和中和效价。我们还将包括 粘膜读数，包括IgA反应，并将检验PICV载体与 具有增强的干扰素-γELISPOT反应(与佐剂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胎盘抗体转移 在母婴抗体转移模型中比较PICV载体疫苗和亚单位RBD疫苗对怀孕的影响。 我们将检测新生幼崽的血清，以检验病毒中和抗体跨越 胎盘。这些实验对人类健康具有很高的相关性，并将为未来的研究奠定基础 在豚鼠妊娠模型中对SARS-CoV-2的挑战研究，反过来可以帮助阐明最佳 控制妇女和婴儿先天性和围产期获得性新冠肺炎病的疫苗战略。

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.