Antigenicity and Immunogenicity of Stabilized prefusion F protein

RSV F糖蛋白是疫苗诱导中和抗体的关键靶点。我们的假设是，通过定义F的结构和与中和相关的表位结构，将有助于理解抗体中和的机制。这将使新的抗原设计成为可能。表征F的化学和翻译后修饰也将促进改进的疫苗抗原设计。我们已经在一期临床试验VRC317中测试了我们的稳定的预融合F蛋白进行临床评估。在这项试验中，我们正在评估我们的稳定化预融合F蛋白(DS-Cav1)与明矾佐剂或与明矾佐剂一起在健康成年人中的安全性、耐受性和免疫原性。我们评估了人类对单剂DS-Cav1的免疫反应，发现接种DS-Cav1疫苗后，中和活性增加了7-15倍。对抗体反应的分析表明，DS-Cav1免疫既能诱导与蛋白质的融合形式结合的抗体，又能诱导与融合前构象和融合后构象结合的抗体。DS-Cav1疫苗诱导的中和活性高于RSV感染诱导的中和活性，是后F或未知F结构诱导的中和活性的2-5倍。这项工作为基于结构的疫苗设计提供了临床概念验证。 除了中和抗体外，在候选疫苗中，诱导保护性的、免于疾病的CD8+T细胞反应也是可取的。这些研究包括评估表达稳定的Pre-F蛋白或野生型F蛋白的基因和载体疫苗对可溶性Pre-F蛋白免疫的影响。我们还与合作者一起评估其他表达我们稳定的Pre-F蛋白的载体的免疫原性。

The RSV F glycoprotein is a key target for vaccine-induced neutralizing antibody. Our hypothesis is that understanding the mechanism of antibody neutralization will be facilitated by defining the structure of F and the structure of epitopes associated with neutralization. This will allow novel antigen design. Characterizing the chemistry and post-translational modifications in F will also promote improved vaccine antigen design. We have tested our stabilized prefusion F protein into clinical evaluation in a Phase 1 clinical trial, VRC 317. In this trial, we are evaluating safety, tolerability, and immunogenicity of our stabilized prefusion F protein (DS-Cav1) with or with alum adjuvant in healthy adults. We have assessed the immune response to a single dose of DS-Cav1 in humans and found that DS-Cav1 vaccination elicits a 7-15-fold increase in neutralizing activity. Dissection of the antibody response showed that DS-Cav1 immunization elicited both antibodies that bind to the prefusion form of the protein and antibodies that bind to both the prefusion and postfusion conformation. The neutralizing activity elicited by DS-Cav1 vaccination is higher than that elicited by RSV infection, and 2-5 fold higher than neutralizing activity elicited by post-F or non-determined F structure. This work serves as a clinical proof-of-concept for structure-based vaccine design. In addition to neutralizing antibodies, the induction of both protective, disease-sparing CD8+ T cell responses are desirable in a vaccine candidate. These studies include evaluation of gene and vector-based vaccines expressing either the stabilized Pre-F protein or the wildtype F protein to vaccination with soluble Pre-F protein. We are also working with collaborators to assess immunogenicity of other vectors expressing our stabilized Pre-F protein.