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

摘要 疟疾特异性CD 8 + T细胞长期以来一直被认为可以控制疟疾的肝脏阶段。我们最近展示了 它们也能杀死感染间日疟原虫的网织红细胞。然而，T细胞靶向抗原 在任何阶段由寄生虫感染细胞上的主要组织相容性复合体（MHC）I类分子呈递 在很大程度上是未知的;知识的缺乏阻碍了合理设计的T细胞的发展， 疟疾疫苗。在初步实验中，我们确定了在P. 间日疟原虫感染的网状细胞该分析揭示了许多MHC-I结合肽来源于 丰富的管家蛋白，如组蛋白和核糖体蛋白，它们在细胞中高度保守， 疟原虫--目前疫苗策略中没有的靶点。这一发现创造了 这是一个独特的机会，可以开发泛疟原虫疫苗，将T细胞诱导到经验证的靶点。没想到， 在多个供体中鉴定了几种肽，而不管它们的MHC单倍型和我们的初步数据 显示这部分是由于在MHC-E（一种非多态性MHC-Ib分子）上肽呈递。因此我们 假设MHC-E限制性CD 8 + T细胞有助于T细胞介导的抗疟疾保护， 这可以用于疫苗设计，使用基于巨细胞病毒（CMV）的载体，唯一的平台， 其可以被编程以引发对插入的抗原的MHC-E限制性CD 8 + T细胞应答。这一假设 将使用间日疟原虫的食蟹猴非人灵长类动物模型在三个特定目标中进行测试， 在人间日疟原虫感染的样品中的验证：在目的1中，我们将确定MHC-E对间日疟原虫感染的相对贡献。 将间日疟原虫肽呈递给CD 8 + T细胞，并研究MHC-E靶向在CD 8 + T细胞中的可能作用。 感染的网织红细胞的细胞杀伤（iRetics）。在目标2中，我们将描述个体间日疟原虫的作用， iRetics的MHC-E限制性CD 8 + T细胞靶向中的抗原。这将通过识别MHC- E/肽特异性T细胞受体和检查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被选定抗原诱导的MHC-E限制性CD 8 + T细胞 用遗传修饰的恒河猴巨细胞病毒载体（RhCMV）免疫的猕猴， MHC-E限制性CD 8 + T细胞。在目标3中，我们将比较基于RhCMV的间日疟原虫疫苗诱导MHC-E或 MHC-Ia-限制性应答选择，保守的抗原方面，他们的能力，以防止P。 猕猴中的食蟹猴攻击。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引起的复发性血液阶段。这个合作项目 汇集了不同的专门知识，如果成功，将提供一种高度创新的疟疾防治方法 疫苗开发，预计将对疫苗研究产生持久的影响。

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.