Synthetic nanoparticle vaccines for RSV

描述（由申请人提供）：呼吸道合胞病毒（RSV）是婴幼儿和老年人严重下呼吸道疾病的最重要原因。尽管经过了几十年的努力，仍没有获得批准的疫苗。早期开发福尔马林灭活疫苗（FI-RSV）的尝试导致环境暴露于RSV后疾病增强。由于免疫原性差和反应时间短，开发重组亚单位疫苗的努力取得了有限的成功。在过去的几年中，一些研究表明，与RSV感染相关的不良炎症反应，可能是FI-RSV疫苗的失败，与RSV- g蛋白有关，RSV- g蛋白在病毒附着于靶细胞中起关键作用。RSV-G含有一个CX3C趋化因子基序，该基序与CX3CR1趋化因子受体相互作用，并似乎引发炎症性th2偏向性免疫反应，有助于疾病发病。我们已经证明，对CX3C基序的抗体反应可以降低病毒的感染性，抑制RSV-G趋化因子调节活性，减少感染后的肺部炎症。引起IFN反应的疫苗设计也可能有助于减少与RSV感染相关的th2偏倚反应和肺部炎症。在这个I期项目中，我们将使用一种创新的方法来生产合成纳米颗粒疫苗，该疫苗携带RSV- g肽，与RSV t细胞靶抗原结合，有利于IFN反应。纳米颗粒的制备方法是将带相反电荷的多肽（包括携带抗原有效载荷的设计肽（DP））逐层沉积，在固体纳米级核心上构建超薄薄膜。我们已经证明，通过这种策略制成的疫苗提高了t细胞和抗体靶表位的免疫原性，而不会引发不良的炎症反应。目前的提案将(1)确定最佳的DP设计，以增加纳米颗粒的负载和稳定性，(2)选择基于抗体和t细胞反应的效力和表型的LbL纳米颗粒疫苗设计（特别强调IFN反应，已被证明可以提高对RSV疾病的保护），以及(3)在测量病毒和趋化因子中和，抑制趋化性，以及保护小鼠免受RSV攻击后的病毒负担和肺部炎症。RSV-G DP将包括一个与趋化因子基序重叠的CD4 t细胞表位，并将由RSV-M2或RSV-F的t细胞靶表位补充，以提供额外的IFN调节Th1/Th2平衡。因此，本研究中生产的新型纳米颗粒疫苗将有能力引发多种机制的保护，防止RSV感染和异常肺部炎症。该项目的交付成果是一种或多种在动物模型中证明安全性和有效性的LbL RSV-G候选疫苗；这些候选药物将在随后的II期项目中进一步开发，该项目将完成新药研究申请和最终临床试验所需的步骤。将这种创新方法应用于RSV疫苗开发也将影响其他传染病疫苗的开发。

DESCRIPTION (provided by applicant): Respiratory syncytial virus (RSV) is the most important cause of severe lower respiratory tract illness in infants and the elderly. There is no approved vaccine despite decades of effort. Early attempts to develop a formalin- inactivated vaccine (FI-RSV) resulted in disease enhancement following environmental exposure to RSV. Efforts to develop recombinant subunit vaccines have met with limited success due to poor immunogenicity and short-lived responses. Over the last few years, several avenues of study have suggested that the adverse inflammatory responses associated with RSV infection, and perhaps the failure of the FI-RSV vaccine, are linked to the RSV-G protein which plays a critical role in virus attachment to target cells. RSV-G contains a CX3C chemokine motif that interacts with the CX3CR1 chemokine receptor and appears to elicit an inflammatory Th2-biased immune response that contributes to disease pathogenesis. We have shown that antibody responses to the CX3C motif can reduce virus infectivity, inhibit RSV-G chemokine-modulating activity and reduce lung inflammation following infection. Vaccine designs that elicit an IFN response may also help to reduce the Th2-biased response and lung inflammation associated with RSV infection. In this Phase I project, we will use an innovative approach to produce synthetic nanoparticle vaccines carrying the RSV-G peptide coupled with RSV T-cell target antigens that favor IFN responses. Nanoparticles will be fabricated using layer-by-layer (LbL) deposition of oppositely charged polypeptides, including designed peptides (DP) carrying the antigen payload, to build ultrathin films on solid nano-sized cores. We have shown that vaccines made by this strategy improve the immunogenicity of both T-cell and antibody target epitopes without triggering adverse inflammatory reactions. The current proposal will (1) identify the optimal DP designs for increasing loading and stability of nanoparticles, (2) select LbL nanoparticle vaccine designs based on potency and phenotype of antibody and T-cell responses induced (with particular emphasis on IFN responses that have been shown to improve protection from RSV disease), and (3) test the biological activity of antibody responses in assays measuring virus and chemokine neutralization, inhibition of chemotaxis, and protection of mice from viral burden and lung inflammation following challenge with RSV. The RSV-G DP will include a CD4 T-cell epitope that overlaps the chemokine motif, and will be complemented by addition of T-cell target epitopes from RSV-M2 or RSV-F to provide additional IFN modulation of the Th1/Th2 balance. Thus, the novel nanoparticle vaccines produced in this study will have the capacity to elicit multiple mechanisms of protection against RSV infection and aberrant lung inflammation. The deliverable of this project is one or more LbL RSV-G vaccine candidates with demonstrated safety and efficacy in animal models; these candidates will be further developed in a subsequent Phase II project that will complete the steps necessary for Investigational New Drug application filing and eventual clinical testing. The application of this innovative approach to RSV vaccine development will also impact vaccine development for other infectious diseases. PUBLIC HEALTH RELEVANCE: This project will use an innovative nanoparticle technology to produce novel vaccine candidates for respiratory syncytial virus. Since the vaccines contain a portion of the virus responsible for both infection and host inflammation, vaccine-induced immune responses will not only reduce the rate of RSV infectivity but will also alleviate the lung inflammation associated with RSV disease. A vaccine emerging from this effort will address a large unmet need in infants, children, elderly and immunocompromised patients.