Emory Vaccine Center, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia, USA.
Infect Immun. 2012 Apr;80(4):1491-501. doi: 10.1128/IAI.05980-11. Epub 2012 Jan 17.
We have previously reported the design and expression of chimeric recombinant proteins as an effective platform to deliver malaria vaccines. The erythrocytic and exoerythrocytic protein chimeras described included autologous T helper epitopes genetically linked to defined B cell epitopes. Proof-of-principle studies using vaccine constructs based on the Plasmodium yoelii circumsporozoite protein (CSP) and P. yoelii merozoite surface protein-1 (MSP-1) showed encouraging results when tested individually in this mouse malaria model. To evaluate the potential synergistic or additive effect of combining these chimeric antigens, we constructed a synthetic gene encoding a hybrid protein that combined both polypeptides in a single immunogen. The multistage vaccine was expressed in soluble form in Escherichia coli at high yield. Here we report that the multistage protein induced robust immune responses to individual components, with no evidence of vaccine interference. Passive immunization using purified IgG from rabbits immunized with the hybrid protein conferred more robust protection against the experimental challenge with P. yoelii sporozoites than passive immunization with purified IgG from rabbits immunized with the individual proteins. High antibody titers and high frequencies of CD4(+)- and CD8(+)-specific cytokine-secreting T cells were elicited by vaccination. T cells were multifunctional and able to simultaneously produce interleukin-2 (IL-2), gamma interferon (IFN-γ), and tumor necrosis factor alpha (TNF-α). The mechanism of vaccine-induced protection involved neutralizing antibodies and effector CD4(+) T cells and resulted in the control of hyperparasitemia and protection against malarial anemia. These data support our strategy of using an array of autologous T helper epitopes to maximize the response to multistage malaria vaccines.
我们之前曾报道过嵌合重组蛋白的设计和表达，这是一种将疟疾疫苗递送至细胞内的有效平台。所描述的红细胞内和红细胞外蛋白嵌合体包括与定义的 B 细胞表位基因相连的自身辅助性 T 细胞表位。基于疟原虫 yoelii 环子孢子蛋白（CSP）和疟原虫 yoelii 裂殖体表面蛋白-1（MSP-1）的疫苗构建体的原理验证研究表明，在这种小鼠疟疾模型中单独测试时，结果令人鼓舞。为了评估组合这些嵌合抗原的潜在协同或相加作用，我们构建了一个编码融合蛋白的合成基因，该蛋白将两种多肽在单个免疫原中结合在一起。多阶段疫苗在大肠杆菌中以高产量可溶性形式表达。在这里，我们报告该多阶段蛋白诱导了对各成分的强烈免疫反应，没有疫苗干扰的证据。用从用融合蛋白免疫的兔子中纯化的 IgG 进行被动免疫，比用从用各蛋白免疫的兔子中纯化的 IgG 进行被动免疫，能更有效地保护实验性疟原虫孢子虫感染。接种疫苗引起了高抗体滴度和高频率的 CD4(+)-和 CD8(+)-特异性细胞因子分泌 T 细胞。T 细胞具有多功能性，能够同时产生白细胞介素-2（IL-2）、γ干扰素（IFN-γ）和肿瘤坏死因子-α（TNF-α）。疫苗诱导保护的机制涉及中和抗体和效应 CD4(+)T 细胞，并导致控制过度寄生和防止疟疾贫血。这些数据支持我们使用一系列自身辅助性 T 细胞表位的策略，以最大限度地提高多阶段疟疾疫苗的反应。
