A universal malaria T cell vaccine based on HLA-E presentation

摘要 人们早就知道疟疾特异性 CD8 T 细胞可以控制疟疾的肝脏阶段。我们最近展示了 它们还可以杀死感染间日疟原虫的网织红细胞。然而，T 细胞靶向抗原 由主要组织相容性复合物 (MHC) I 类分子在任何阶段的寄生虫感染细胞上呈递 很大程度上是未知的；缺乏知识阻碍了合理设计的 T 细胞的发展 基于疟疾的疫苗。在初步实验中，我们确定了 P. 上呈现的 MHC-I 肽组。 间日感染的网织红细胞。该分析表明许多 MHC-I 结合肽源自 丰富的管家蛋白，例如组蛋白和核糖体蛋白，它们在细胞间高度保守 疟原虫种类——当前疫苗策略中未体现的目标。这一发现因此创造了 这是开发泛疟原虫疫苗的独特机会，可诱导 T 细胞到达经过验证的目标。没想到， 无论 MHC 单倍型和我们的初步数据如何，在多个供体中都鉴定出了几种肽 显示这部分是由于 MHC-E（一种非多态性 MHC-Ib 分子）上的肽呈递所致。我们因此 假设 MHC-E 限制性 CD8 T 细胞有助于 T 细胞介导的抗疟疾保护作用 这可以用于使用基于巨细胞病毒（CMV）的载体进行疫苗设计，这是唯一的平台 可以对其进行编程以引发 MHC-E 限制的 CD8 T 细胞对插入抗原的反应。这个假设 将使用间日疟原虫的食蟹猴非人类灵长类动物模型进行三个特定目标的测试 在人间日疟原虫感染的样本中进行验证：在目标 1 中，我们将确定 MHC-E 对 将间日疟原虫肽呈递给 CD8 T 细胞并研究 MHC-E 靶向在 CD8 T 中的可能作用 杀死受感染的网织红细胞（iRetics）。在目标 2 中，我们将描述个体间日疟原虫的作用 MHC-E 限制性 CD8 T 细胞靶向 iRetics 中的抗原。这将通过识别 MHC-来完成 E/肽特异性 T 细胞受体并检查 TCR 转染的 T 细胞靶向 iRetics 的能力。在 此外，我们将类似地表征恒河猴中诱导选定抗原的 MHC-E 限制性 CD8 T 细胞 使用转基因恒河猴巨细胞病毒载体（RhCMV）进行免疫接种的猕猴，该载体专门引发 MHC-E 限制性 CD8 T 细胞。在目标 3 中，我们将比较基于 RhCMV 的间日疟原虫疫苗引发 MHC-E 或 MHC-Ia 限制性地对选定的、保守的抗原作出反应，以预防疟原虫的能力。 恒河猴的食蟹猴挑战。具体来说，我们将监测对肝脏阶段的保护， 原发性血液阶段和由休眠肝脏阶段产生的复发性血液阶段。此次合作计划 汇集不同的专业知识，如果成功，将为疟疾提供高度创新的方法 疫苗的开发预计将对疫苗研究产生持久影响。

ABSTRACT Malaria-specific CD8+ T cells have long been known to control the liver stages of malaria. We recently showed that they can also kill reticulocytes infected with Plasmodium vivax. However, the T cell targeted antigens presented by major histocompatibility complex (MHC) class I molecules on parasite-infected cells at any stage are largely unknown; a lack of knowledge that has hampered the development of rationally designed, T cell- based vaccines for malaria. In preliminary experiments we determined the MHC-I peptidome presented on P. vivax-infected reticulocytes. This analysis revealed that many MHC-I-bound peptides are derived from abundant house-keeping proteins such as histones and ribosomal proteins that are highly conserved among Plasmodium species—targets not represented in current vaccine strategies. This discovery thus creates the unique opportunity to develop pan-Plasmodium vaccines eliciting T cells to validated targets. Unexpectedly, several peptides were identified in multiple donors regardless of their MHC-haplotype and our preliminary data show this is in part due to peptide presentation on MHC-E, a non-polymorphic MHC-Ib molecule. We therefore hypothesize that MHC-E-restricted CD8+ T cells contribute to T cell-mediated protection against malaria and that this can be exploited for vaccine design using cytomegalovirus (CMV)-based vectors, the only platform that can be programmed to elicit MHC-E-restricted CD8+ T cell responses to inserted antigens. This hypothesis will be tested in three specific aims using the P. cynomolgi non-human primate model of P. vivax with validation in human P. vivax-infected samples: In Aim 1 we will determine the relative contribution of MHC-E to presentation of P.vivax peptides to CD8+ T cells and investigate a possible role of MHC-E-targeting in CD8+ T cell killing of infected reticulocytes (iRetics). In Aim 2 we will characterize the role of individual P. vivax antigens in MHC-E-restricted CD8+ T cell targeting of iRetics. This will be accomplished by identifying MHC- E/peptide-specific T cell receptors and examining the ability of TCR-transfected T cells to target iRetics . In addition, we will similarly characterize MHC-E-restricted CD8+ T cells elicited to selected antigens in rhesus macaques immunized with genetically modified rhesus cytomegalovirus vectors (RhCMV) that elicit exclusively MHC-E-restricted CD8+ T cells. In Aim 3, we will compare RhCMV-based P. vivax vaccines eliciting MHC-E or MHC-Ia-restricted responses to selected, conserved antigens with respect to their ability to protect against P. cynomolgi challenge in rhesus macaques. Specifically, we will monitor protection against the liver stage, primary blood stage and relapsing blood stage resulting from dormant liver stages. This collaborative program brings together diverse expertise and, if successful, will provide a highly innovative approach to malaria vaccine development that is expected to have a lasting impact on vaccine research.