Malaria Vaccine Adjuvant Immunogenicity and Safety

描述（由申请人提供）：在该R21申请中，我们提出使用充分表征的疟疾疫苗候选物作为模型免疫原来评估纳米颗粒制剂的功效和安全性的细胞、分子和免疫相关性。一种基于Pfs 25蛋白的疫苗针对寄生虫的性阶段，提供了减少疟疾传播的直接方法。在恶性疟原虫中，Pfs 230和Pfs 48/45蛋白在红细胞内配子体阶段内产生，Pfs 25在蚊子阶段受精卵发育成动合子期间表达，代表了传播阻断抗体的良好建立的靶抗原。识别这些蛋白质中特定构象表位的抗体是蚊子中疟原虫感染性的有效阻断剂。我们最近成功地在大肠杆菌中重组表达和纯化了重折叠的Pfs 25，首次以接近天然的构象。杆菌纯化蛋白（rPfs 25）在实验佐剂中引起小鼠强烈的免疫原性。需要开发更好和更安全的佐剂和递送方法，以最终用于人类。纳米颗粒作为安全有效的疫苗佐剂正在迅速获得接受。我们建议开发Pfs 25-纳米颗粒制剂（目的1）并评估近交系和远交系小鼠中的功能性免疫应答（目的3）。我们还建议研究疫苗注射部位的免疫应答相关宿主基因表达变化，以获得Pfs 25纳米颗粒疫苗效力的机制见解（目的2）。最后，还提出了研究相关疫苗安全性参数的建议（目标4）。这些研究将提供对纳米颗粒制剂的免疫原性功效和安全性的细胞和分子相关性的更好理解，并且通常还为疫苗开发的更深入研究提供基础。

DESCRIPTION (provided by applicant): In this R21 application we propose to assess cellular, molecular and immune correlates of efficacy and safety of nanoparticle formulations using a well characterized malaria vaccine candidate as a model immunogen. A vaccine based on Pfs25 protein targeting the sexual stages of the parasite provides a direct approach to reduce malaria transmission. In Plasmodium falciparum, Pfs230 and Pfs48/45 proteins produced within the intra-erythrocytic gametocyte stages and Pfs25, expressed during the mosquito stage development of zygote into ookinete, represent well established target antigens of transmission-blocking antibodies. Antibodies recognizing specific conformational epitopes in these proteins are potent blockers of infectivity of malaria parasites in the mosquito. We have recently succeeded in recombinant expression and purification of re-folded Pfs25, for the first time in near native conformation, in E. coli. The purified protein (rPfs25) in experimental adjuvants elicited strong immunogenicity in mice. Better and safer adjuvants and delivery methods need to be developed for eventual human applicability. Nanoparticles are fast gaining acceptability as safe and effective vaccine adjuvants. We propose to develop Pfs25 - nanoparticle formulations (Aim 1) and evaluate functional immune response in inbred and outbred mice (Aim 3). We also propose to study the immune response-related host gene expression changes at the site of vaccine injection to gain mechanistic insights of Pfs25-nanoparticle vaccine efficacy (Aim 2). Finally studies are also proposed to investigate relevant vaccine safety parameters (Aim 4). These studies will provide better understanding of cellular and molecular correlates of immunogenic efficacy and safety of nanoparticle formulations, and also provide the basis for more in depth studies on vaccine development, in general.