Development of Novel Chagas Vaccines

描述（由申请人提供）：克氏锥虫是一种重要的人类病原体，每年感染1200 - 2000万人，造成10- 50，000人死亡。病媒控制措施取得了一些成功，但现有的药物疗法疗效低、毒性高，而且没有特定的疫苗进入人体试验。迫切需要一种安全有效的疫苗来保护4000万至1亿有可能感染这种致命疾病的人。检测到针对寄生虫裂解物和多种T. Cruzi蛋白在慢性感染中的作用事实上，T. cruzi特异性IFN-？产生CD 8 + T细胞与减少疾病进展相关。我们已经建立了动物模型，仔细分析疫苗诱导的免疫反应和与T。克氏感染一些研究表明，CD 4 + T细胞在保护性免疫的启动功能中是必需的，而CD 8 + T细胞对于效应功能和寄生虫清除是必需的。T. Cruzi转唾液酸酶（TS）抗原可以诱导有效的鼠保护作用，以抵抗正常致死的全身和亚致死的粘膜T。cruzi挑战;然而，TS疫苗尚未优化用于人类使用。此外，大TS基因家族占所有T. cruzi基因，TS抗原的表达可能参与了寄生虫的免疫逃避。我们将通过比较编码来自功能性TS基因（编码12-15种酶活性蛋白）、非功能性TS基因（>700个基因）和哺乳动物阶段非TS基因的表位的疫苗来解决后一种可能性。我们建议从这些重要的T.利用现有技术免疫信息学，预测cruzi蛋白集合结合常见的HLA等位基因（提供与>95%的所有人类群体相关的选择覆盖率）。将合成预测的表位序列，并将采用HLA结合测定来验证MHC结合。我们将与加州大学洛杉矶分校的Meymandi博士合作，从T. cruzi（和未感染的对照）和刺激纯化的PBMC与上述肽在IFN-γ？ELISPOT和流式细胞术测定。基于这些筛选试验的结果，我们将设计编码这些T细胞表位的新型疫苗，并在“人源化”HLA A2/DR 1双转基因小鼠中测试其预防和治疗功效。我们的研究结果将为进行第一阶段恰加斯病疫苗试验提供所需的关键数据。

DESCRIPTION (provided by applicant): Trypanosoma cruzi is an important human pathogen responsible for 10-50,000 deaths/year infecting 12-20 million people. Vector control measures have met with some success but available drug therapies have low efficacy and high toxicity, and no specific vaccines have entered human trials. There is a desperate need for a safe and effective vaccine to protect the 40-100 million individuals at risk of acquiring this deadly diseas. Robust CD8+ T cell responses are detected against parasite lysate and a variety of T. cruzi proteins during chronic infection. In fact, increased frequencies of T. cruzi-specific IFN-? producing CD8+ T cells correlate with decreased disease progression. We have developed animal models to carefully analyze vaccine-induced immune responses and cardiac pathology associated with T. cruzi infection. Several studies have shown that CD4+ T cells are necessary during priming functions of protective immunity, and CD8+ T cells are essential for effector function and parasite clearance. T. cruzi trans-sialidase (TS) antigens can induce potent murine protection against normally lethal systemic and sub-lethal mucosal T. cruzi challenges; however, TS vaccines have not been optimized for human use. In addition, the large TS gene family represents >5% of all T. cruzi genes, and expression of some TS antigens may be involved in parasite immunoevasion. We will address this latter possibility by comparing vaccines encoding epitopes from functional TS genes (encoding the 12-15 enzymatically active proteins), non-functional TS genes (>700 genes), and mammalian stage non-TS genes. We propose to identify key parasite epitopes from these important T. cruzi protein sets predicted to bind common HLA alleles (providing selection coverage relevant for >95% of all human populations) utilizing state- of-the-art immunoinformatics. Predicted epitope sequences will be synthesized and HLA binding assays will be employed to validate MHC binding. In collaboration with Dr. Meymandi at UCLA, we will obtain blood samples from individuals infected with T. cruzi (and uninfected controls) and stimulate purified PBMC with peptides described above in IFN-?? ELISPOT and flow cytometric assays. Based on results from these screening assays, we will design novel vaccines encoding these T cell epitopes, and test their prophylactic and therapeutic efficacies in 'humanized' HLA A2/DR1 dual transgenic mice. The outcome of our studies will provide key data required for proceeding with phase I Chagas vaccine trials.