Proteome-wide cellular immunity approach to P. falciparum antigen identification

描述(由申请人提供)：该项目的长期目标是通过挖掘恶性疟原虫基因组序列，识别和优先考虑疟疾疫苗开发的新的恶性疟原虫抗原和表位，这些抗原和表位是在多种遗传限制的情况下暴露于恶性疟原虫的个人所识别的。实验数据表明，暴露于完整的疟原虫可诱导保护性免疫，这支持了疟疾疫苗的可行性。这种保护的抗原性靶标尚未确定。恶性疟原虫表达约5300种蛋白质，每一种蛋白质都是保护性免疫反应的潜在靶标。虽然恶性疟原虫基因组、蛋白质组和转录组现在已经被阐明，但如何利用这些信息进行疫苗开发还不是很明显。目前的应用为这个问题提供了一个解决方案，通过应用一种整合了生物信息学预测、HLA超类型考虑、高通量MHC多肽结合分析和细胞分析的方法。其具体目的是：(1)从在恶性疟原虫生命周期的红细胞前期阶段表达的大约2500个基因的完整集合中，识别与暴露于恶性疟原虫的个体在多种遗传限制背景下识别的免疫优势抗原相对应的蛋白质；(2)对于100个最免疫优势抗原的子集，识别作为恶性疟原虫诱导免疫的目标的CD8+和CD4+T表位，以及它们相关的HLAI和II类限制元件；(3)对于50个抗原，表征不同疟原虫株之间的序列保守程度或免疫交叉反应的五个表位/抗原；(4)评价10种抗原对小鼠子孢子攻击的保护能力。预计拟议的研究将导致确定新的恶性疟原虫抗原，这些抗原将代表对所有种族有效的疫苗的良好候选者。此外，数据将显示保护性免疫反应是针对少数免疫优势抗原，还是广泛分布于大范围的抗原，因此将提供关于候选疟疾疫苗潜在多价的有价值的信息。预计拟议的研究将对疟疾疫苗的开发产生重要成果。它将确定新的恶性疟原虫抗原，这些抗原应该是亚单位疟疾疫苗的良好候选者，这种疫苗将在所有人口中有效，而不分种族。此外，数据将显示保护性免疫反应是针对少数免疫优势抗原，还是广泛分布于大范围的抗原，因此将提供关于候选疟疾疫苗潜在多价的有价值的信息。

DESCRIPTION (provided by applicant): The long-term objective of this project is to identify and prioritize for malaria vaccine development novel P. falciparum antigens and epitopes that are recognized by individuals exposed to P. falciparum in the context of multiple genetic restrictions, by mining the P. falciparum genomic sequence. The feasibility of a malaria vaccine is supported by experimental data demonstrating that protective immunity can be induced by exposure to intact Plasmodium parasites. The antigenic targets of this protection have not been identified. P. falciparum expresses an estimated 5,300 proteins, each of which is a potential target of protective immune responses. Although the P. falciparum genome, proteome, and transcriptome have now been elucidated, it has not been obvious how to use this information for vaccine development. The current application offers a solution to this problem, by applying an integrated approach that incorporates bioinformatic predictions, HLA supertype considerations, high-throughput MHC peptide binding assays, and cellular assays. The specific aims are to: (1) identify, from the complete set of approximately 2500 genes expressed in the pre-erythrocytic stage of the P. falciparum parasite life cycle, those proteins that correspond to immunodominant antigens recognized in the context of multiple genetic restrictions by individuals exposed to P. falciparum; (2) for a subset of the100 most immunodominant antigens, identify the CD8+ and CD4+ T epitopes that are the targets of P. falciparum parasite-induced immunity, and their associated HLA Class I and II restriction elements; (3) for 50 antigens, characterize five epitopes/antigen for extent of sequence conservation or immunological cross-reactivity between different Plasmodium strains; and (4) for 10 antigens, evaluate the capacity to protect against Plasmodium sporozoite challenge in mice. It is expected that the proposed research will result in the identification of novel P. falciparum antigens that will represent good candidates for a vaccine that would be effective in all ethnicities. Additionally, data will demonstrate whether protective immune responses are targeted against only a few immunodominant antigens, or are broadly distributed against a large range of antigens, and will therefore provide valuable information regarding the potential multivalency of candidate malaria vaccines. It is expected that the proposed research will have important outcomes for malaria vaccine development. It will identify novel P. falciparum antigens that should represent good candidates for a subunit malaria vaccine that would be effective in all human populations regardless of ethnicity. Additionally, data will demonstrate whether protective immune responses are targeted against only a few immunodominant antigens, or are broadly distributed against a large range of antigens, and will therefore provide valuable information regarding the potential multivalency of candidate malaria vaccines.