IMMUNOGENICITY OF SYNTHETIC POLYOXIME MALARIA VACCINES

疟疾环子孢子(CS)蛋白的重复B细胞表位构成了合成多肽疫苗的基础，目的是诱导高水平的体液免疫，以阻断感染性子孢子对宿主肝细胞的入侵。利用肟键连接技术构建了恶性疟原虫CS蛋白的T细胞表位(T*)与重复B细胞表位(T1 B)相结合的合成肽疫苗。该三表位多肟疫苗的分支模板核心含有内置的合成脂肽佐剂三棕榈酰基-S-甘油基半胱氨酸(P3C)。最近在日内瓦大学进行了一项小规模的第一阶段试验，以测试(T1BT*)4-P3C多肟疟疾疫苗的安全性和免疫原性。多组分多肟疟疾疫苗被发现在不需要添加外源性佐剂的情况下，在10/10名不同人类白细胞抗原单倍型的志愿者中诱导抗肽抗体反应。目前的赠款申请建议分析多肟免疫志愿者的T细胞和B细胞反应，并分析来自这些志愿者的T细胞系和克隆的遗传限制和效应功能。这些研究将首次对人类对多肟疫苗的反应进行免疫学分析，并首次有机会研究疟疾通用T细胞表位在已确定的II类单倍型个体中的功能。初步的血清学结果还表明，虽然所有接种者都产生了抗肽抗体，但抗体应答的大小是不同的，有5/10的志愿者达到了高抗体效价(>5120)。为了优化体液免疫，含有不同T和B细胞比例和构型的多肟将与人类可接受的不同佐剂配方一起进行测试。将在近交系小鼠、人类白细胞抗原II类转基因小鼠和澳大利亚猴身上进行免疫原性检测。将在约氏疟原虫啮齿动物疟疾模型中研究旨在诱导高水平体液和细胞免疫的多肟疫苗的保护效果。对(T1BT*)4-P3C免疫志愿者T、B细胞免疫应答的分析、多肟疫苗配方的优化以及在啮齿动物疟疾模型中的效力研究，将为高免疫原性合成肽疟疾疫苗的开发提供实验依据，并为支持多肟疫苗在人类志愿者身上进行额外的第一阶段试验提供临床前数据。

The repeat B cell epitopes of the malaria circumsporozoite (CS) protein have formed the basis of synthetic peptide vaccines aimed at eliciting high levels of humoral immunity to block the invasion of the host hepatocytes by the infectious sporozoite. A synthetic peptide vaccine, containing repeat B cell epitopes (T1 B) combined with a universal T cell epitope (T*) of the P. falciparum CS protein, has been constructed using oxime bond ligation technology. The branched template core of the tri-epitope polyoxime vaccine contains the built-in synthetic lipopeptide adjuvant tripalmitoyl-S-glyceryl cysteine (P3C). A small-scale phase I trial to test the safety and immunogenicity of the (T1BT*)4-P3C polyoxime malaria vaccine has recently been carried out at the University of Geneva. The multicomponent polyoxime malaria vaccine was found to elicit anti-peptide antibody responses in 10/10 volunteers of diverse HLA haplotypes, without requiring the addition of exogenous adjuvant. The current grant application proposes to analyze the T cell and B cell responses of the polyoxime immunized volunteers and to assay the genetic restriction and effector functions of T cell lines and clones derived from these volunteers. These studies will provide the first immunological analysis of the human response to a polyoxime vaccine, as well as the first opportunity to investigate the function of a malaria universal T cell epitope in individuals of defined class II haplotypes. The preliminary serological results also demonstrate that, while anti-peptide antibodies were elicited in all the vaccinees, the magnitude of the antibody response was variable, reaching high antibody titers (greater than 5120) in 5/10 of the volunteers. To optimize humoral immunity, polyoximes containing varying T and B cell ratios and configurations would be tested in combination with different adjuvant formulations acceptable for human use. Immunogneicity would be assayed in inbred strains of mice, as well as HLA class II transgenic mice and in Aotus monkeys. The protective efficacy of polyoxime vaccines designed to elicit high levels of humoral, as well as cellular, immunity would be studied in the P. yoelii rodent malaria model. The analysis of the T and B cell responses of the (T1BT*)4-P3C immunized volunteers, the optimization of polyoxime vaccine formulation and the efficacy studies in the rodent malaria model will provide the experimental basis for the development of highly immunogenic synthetic peptide malaria vaccines as well as the preclinical data to support additional Phase I testing of polyoxime vaccines in human volunteers.