Synthetic nanoparticle vaccines for RSV

描述（由申请方提供）：呼吸道合胞病毒（RSV）是婴儿和老年人严重下呼吸道疾病的最重要原因。尽管经过几十年的努力，仍然没有批准的疫苗。开发福尔马林灭活疫苗（FI-RSV）的早期尝试导致在环境暴露于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，几种研究途径表明，与RSV感染相关的不良炎症反应以及FI-RSV疫苗的失败可能与RSV-G蛋白有关，RSV-G蛋白在病毒附着到靶细胞中起关键作用。RSV-G含有CX3C趋化因子基序，其与CX3CR1趋化因子受体相互作用，并且似乎引发有助于疾病发病机制的炎性Th2偏向性免疫应答。我们已经表明，抗体对CX3C基序的反应可以降低病毒感染性，抑制RSV-G趋化因子调节活性，并减少感染后的肺部炎症。引发IFN应答的疫苗设计也可能有助于减少与RSV感染相关的Th2偏向性应答和肺部炎症。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肽与有利于IFN应答的RSV T细胞靶抗原偶联。纳米颗粒将使用带相反电荷的多肽（包括携带抗原有效载荷的设计肽（DP））的逐层（LbL）沉积来制造，以在固体纳米尺寸的核上构建生物膜。我们已经证明，通过这种策略制备的疫苗提高了T细胞和抗体靶表位的免疫原性，而不会引发不良炎症反应。目前的建议将（1）确定用于增加纳米颗粒的负载和稳定性的最佳DP设计，（2）基于抗体的效力和表型以及诱导的T细胞应答选择LbL纳米颗粒疫苗设计。（特别强调IFN应答，其已显示改善对RSV疾病的保护），和（3）在测定中测试抗体应答的生物活性，所述测定测量病毒和趋化因子中和、趋化性抑制和在用RSV攻击后保护小鼠免于病毒负荷和肺部炎症。RSV-G DP将包括与趋化因子基序重叠的CD4 T细胞表位，并将通过添加来自RSV-M2或RSV-F的T细胞靶表位进行补充，以提供对Th1/Th2平衡的额外IFN调节。因此，本研究中产生的新型纳米颗粒疫苗将具有引发针对RSV感染和异常肺部炎症的多种保护机制的能力。该项目的可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;这些候选疫苗将在随后的II期项目中进一步开发，该项目将完成研究性新药申请提交和最终临床试验所需的步骤。这种创新方法在RSV疫苗开发中的应用也将影响其他传染病的疫苗开发。 公共卫生相关性：该项目将使用创新的纳米颗粒技术来生产呼吸道合胞病毒的新型候选疫苗。由于疫苗含有负责感染和宿主炎症的病毒的一部分，因此疫苗诱导的免疫应答不仅会降低RSV感染率，而且还会减轻与RSV疾病相关的肺部炎症。这项工作产生的疫苗将解决婴儿、儿童、老年人和免疫功能低下患者的大量未满足需求。

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.