Synthetic nanocapsule malaria vaccines

描述（由申请人提供）：该项目的目标是基于恶性疟原虫（人类疟疾的病原体）环子孢子（CS）蛋白的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，但先前的工作已经表明，子孢子阶段的CS蛋白含有许多被受保护宿主的抗体和T细胞识别的候选疫苗表位。这些包括中心重复区（B）的保守抗体表位和两个T细胞表位：与中心重复区的N-末端重叠的T1和位于蛋白质的C-末端附近的T*。在临床前和临床研究中，用三肽构建体T1 BT * 免疫引发了与子孢子表面上的天然蛋白质结合的CS抗体，抑制它们的运动性和宿主肝细胞的侵入，从而破坏寄生虫生命周期并预防引起临床疾病的未闭血液期感染。各种CS疫苗策略的成功在一定程度上受到生产规模扩大、免疫原性差和佐剂剂量限制性毒性方面的困难的影响。为了克服这些问题，将采用一种创新的方法，该方法使用人工生物膜的逐层（LbL）制造来将CS表位并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在一次或两次免疫接种后引发有效的免疫应答，避免了不期望的应答，例如炎性细胞因子的释放。纳米帽通过多种途径将其抗原有效载荷递送至树突细胞，包括吞噬作用，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。用LbL纳米胶囊免疫平衡了T细胞应答，包括IFN和IL-4 ELISPOT，以及效应CTL活性。由LbL纳米胶囊引发的免疫应答明显不包括对用于产生生物膜的基质多肽的抗体应答，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，将设计和制备含有恶性疟原虫CS的T1、B和/或T* 表位或伯氏疟原虫的CTL表位的单价和多价LbL纳米帽。通过监测ELISPOT和体内CTL对T细胞表位的应答以及抗体对B表位的应答，在小鼠中研究免疫原性。将使用表达含有恶性疟原虫CS（PfPb）的B表位的杂交CS的转基因伯氏疟原虫（小鼠病原体）来研究疗效，以测量保护性抗体，或使用野生型伯氏疟原虫来测量保护性CD 8 + T细胞应答。该项目将产生合成的纳米胶囊疫苗候选物，其引发有效的CS特异性免疫应答，并在不使用有毒佐剂的情况下提供对疟疾的保护。 公共卫生相关性：该项目利用创新的疫苗制造技术生产有效的疟疾疫苗。这些疫苗由对人类使用安全的材料制成的生物膜制成，并通过合成化学方法制造，不含动物或细胞培养产物或副产物。这些疫苗是有效的、安全的，并且不需要限制疫苗效用的有毒佐剂。

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.