Synthetic nanocapsule malaria vaccines

项目描述（由申请人提供）：本项目的目标是基于人类疟疾病原体恶性疟原虫环孢子子蛋白表位生产新型合成疟疾疫苗。疟疾是发展中世界的主要疾病之一，每年造成2亿至5亿新感染病例和100多万人死亡，主要是非洲的幼儿。虽然没有批准的疫苗，但先前的工作表明，孢子子期的CS蛋白含有许多候选疫苗表位，这些表位可被受保护宿主的抗体和t细胞识别。这包括中心重复区域的保守抗体表位(B)和两个T细胞表位：T1重叠在中心重复区域的n端，T*位于蛋白质的c端附近。在临床前和临床研究中，用三肽构建体T1BT*免疫可诱导CS抗体与孢子体表面的天然蛋白结合，抑制其运动和对宿主肝细胞的侵袭，从而破坏寄生虫的生命周期，防止导致临床疾病的血液期感染。由于生产规模困难、免疫原性差以及佐剂的剂量限制性毒性，各种CS疫苗策略的成功在一定程度上受到了限制。为了克服这些问题，将采用一种创新的方法，即使用逐层（LbL）制造人工生物膜，将CS表位纳入合成纳米胶囊疫苗中。目前在多个模型系统中的结果表明，LbL纳米胶囊疫苗在没有佐剂的情况下进行一次或两次免疫后可引起有效的免疫反应，避免了诸如炎症细胞因子释放等不良反应。纳米胶囊通过包括吞噬在内的多种途径将抗原载荷传递给树突状细胞，导致ii类限制性表位的呈递和i类限制性表位的交叉呈递。LbL纳米胶囊免疫引起平衡的t细胞反应，包括IFN和IL-4 elispot，以及效应CTL活性。LbL纳米胶囊引起的免疫反应明显不包括对用于产生生物膜的基质多肽的抗体反应，从而避免了阻碍许多病毒载体疫苗开发的所谓载体或载体效应。在本项目中，将设计和制造含有恶性疟原虫T1、B和/或T*表位或柏氏疟原虫CTL表位的单价和多价LbL纳米胶囊。免疫原性将在小鼠中通过监测ELISPOT和体内CTL对t细胞表位的反应和抗体对B表位的反应来研究。研究人员将使用转基因柏氏疟原虫（小鼠病原体）表达含有恶性疟原虫（PfPb） B表位的杂交CS来检测保护性抗体，或使用野生型柏氏疟原虫来检测保护性CD8+ t细胞反应。该项目将生产合成纳米胶囊候选疫苗，这些候选疫苗可引发有效的cs特异性免疫反应，并在不使用有毒佐剂的情况下提供疟疾保护。

DESCRIPTION (provided by applicant): The goal of this project is to produce novel synthetic malaria vaccines based on epitopes of the circumsporozoite (CS) protein of Plasmodium falciparum, the causative agent of human malaria. Malaria is one of the major diseases in the developing world, causing 200-500 million new infections and over 1 million deaths each year, primarily in young children in Africa. While there is no approved vaccine, previous work has shown that the CS protein of the sporozoite stage contains a number of candidate vaccine epitopes that are recognized by antibodies and T-cells of protected hosts. These include the conserved antibody epitope of the central repeat region (B) and two T-cell epitopes: T1 which overlaps the N-terminus of the central repeat region and T* which is located near the C-terminus of the protein. In preclinical and clinical studies, immunization with the tri-peptide construct T1BT* elicited antibodies to CS that bound to the native protein on the surface of sporozoites, inhibiting their motility and invasion of host hepatocytes, thus disrupting the parasite life cycle and preventing patent blood stage infection responsible for clinical disease. The successes with various CS vaccine strategies have been somewhat moderated by difficulties in production scale-up, poor immunogenicity, and dose-limiting toxicity of adjuvants. To overcome these issues, an innovative approach will be employed which uses layer-by-layer (LbL) fabrication of artificial biofilms to incorporate the CS epitopes in synthetic nanocapsule vaccines. Current results in multiple model systems show that LbL nanocapsule vaccines elicit potent immune responses following one or two immunizations without adjuvants, avoiding undesirable responses such as the release of inflammatory cytokines. The nanocapsules deliver their antigen payload to dendritic cells via multiple pathways including phagocytosis, leading to presentation of Class II-restricted epitopes and cross-presentation of Class I-restricted epitopes. Immunization with LbL nanocapsules elicits balanced T-cell responses including both IFN and IL-4 ELISPOTs, and effector CTL activity. The immune responses elicited by LbL nanocapsules conspicuously do not include antibody responses to the matrix polypeptides used to produce the biofilm, thereby avoiding the so-called vector or carrier effect that has hampered development of many viral vectored vaccines. In this project, mono- and multivalent LbL nanocapsules containing the T1, B, and/or T* epitopes of P. falciparum CS, or the CTL epitope of P. berghei, will be designed and fabricated. Immunogenicity will be studied in mice by monitoring ELISPOT and in vivo CTL responses to the T-cell epitopes and antibody responses to the B epitope. Efficacy will be studied using transgenic P. berghei (mouse pathogen) expressing a hybrid CS containing the B epitope from P. falciparum CS (PfPb) to measure protective antibodies, or wild-type P. berghei to measure protective CD8+ T-cell responses. This project will yield synthetic nanocapsule vaccine candidates that elicit potent CS-specific immune responses and provide protection from malaria without the use of toxic adjuvants. PUBLIC HEALTH RELEVANCE: This project utilizes an innovative vaccine fabrication technology to produce efficacious vaccines for malaria. These vaccines are made of biofilms of materials safe for human use and are fabricated by synthetic chemistry methods with no animal or cell culture products or by-products. The vaccines are potent, safe, and do not require toxic adjuvants that limit vaccine utility.