Role of F Protein Conformation in RSV Vaccine Efficacy

 描述(申请人提供)：大多数婴幼儿的急性病毒性呼吸道疾病是由呼吸道合胞病毒(RSV)引起的。该病毒还会在老年人和免疫功能低下的人群中引起严重疾病，是健康成人人群发病的重要原因。尽管这种病毒在世界范围内造成了巨大的疾病负担，但目前还没有可用的疫苗。有几个问题阻碍了RSV疫苗的开发。首先是安全问题。一种早期福尔马林灭活疫苗(FI-RSV)，刺激了微弱和不平衡的免疫反应，使婴儿在自然暴露于活病毒时容易患上更严重的疾病。第二个问题是许多候选疫苗未能激发保护性免疫反应。第三个问题是自然感染和候选疫苗未能激发长期的保护性记忆反应。所有这些问题归根结底是由于缺乏对刺激保护性和持久的抗RSV免疫反应所涉及的机制的了解。这一建议将检验不同构象的RSV F蛋白影响抗RSV免疫反应特性的假设。目的是确定RSV F蛋白的构象，表达在病毒样颗粒上，刺激高滴度中和抗体和保护性、长寿和记忆性免疫反应，并了解这些反应的产生机制。为了验证这一假说，我们提出了四个目标。具体目的1：用含有稳定融合前和融合后稳定F蛋白的VLP刺激小鼠和棉花大鼠的抗体，表征RSV F蛋白的结合特性。特异性目的2：明确抗G抗体在RSV F蛋白融合前VLP和VLP融合后VLP诱导小鼠和棉鼠中和效价中的作用。具体目的3：以RSV感染的小鼠和棉花大鼠为母体免疫模型，研究融合前后的F蛋白对VLP的免疫应答。特异性目的4：检测融合前后的VLP在小鼠和大鼠体内是否诱导RSV F蛋白特异性的长寿命骨髓相关浆细胞(LLPC)和记忆B细胞。

 DESCRIPTION (provided by applicant): Most acute viral respiratory disease in infants and young children is due to respiratory syncytial virus (RSV). This virus also causes serious disease in elderly and immunocompromised populations and is a significant cause of morbidity in healthy adult populations. Despite the substantial disease burden due to this virus worldwide, there are no vaccines available. Several problems have impeded RSV vaccine development. First is safety. An early formalin-inactivated vaccine (FI-RSV), which stimulated weak and unbalanced immune responses, predisposed infants to more severe disease upon natural exposure to live virus. A second problem is the failure of many vaccine candidates to stimulate protective immune responses. A third problem is the failure of natural infection as well as vaccine candidates to stimulate long-lived, protective memory responses. All these problems are ultimately due to a lack of understanding of mechanisms involved in stimulation of protective as well as durable anti-RSV immune responses. This proposal will test the hypothesis that different conformational forms of RSV F protein impact the properties of anti-RSV immune responses. The goal is to define conformations of RSV F protein, expressed on virus-like particles, that stimulate high titer neutralizing antibodies and protective, long-lived and memory immune responses and to understand the mechanisms responsible for generation of these responses. To test the hypothesis, four aims are proposed. Specific Aim 1: to characterize the RSV F protein binding properties of antibodies stimulated in mice and in cotton rats by VLPs containing stabilized pre-fusion or stabilized post-fusion F protein. Specific Aim 2: to clarify th role of anti-G antibodies in the neutralization titers induced in mice and cotton rats by VLPs containing the pre-fusion form of the RSV F protein and VLPs containing the post-fusion form. Specific Aim 3: to characterize immune responses to VLPs containing pre- and post-fusion forms of F in RSV experienced mice and cotton rats as models for maternal immunization. Specific Aim 4: to determine if VLPs containing the pre-fusion and the post-fusion F proteins induce RSV F protein specific long-lived bone marrow associated plasma cells (LLPC) and memory B cells in both mice and cotton rats.