Structure-based HCV vaccine design

丙型肝炎病毒（HCV）感染的全球负担为1.85亿，每年新增3-4百万例 每年感染。在美国，由于注射吸毒，年轻人的HCV感染正在增加。一 尽管直接作用抗病毒药物（DAA）的开发取得了重大进展，但仍需要预防性疫苗 用于治疗HCV感染。累积的证据已经确定T和B细胞免疫 有助于控制急性HCV感染。本申请的重点是基于B细胞的疫苗， 由于病毒包膜E1 E2糖蛋白的高度变异性， 保护性抗体的天然目标。我们已经证明，E2包膜上的免疫原性区域 HCV的糖蛋白分离成五个表位簇，命名为抗原结构域A-E， 区域1（HVR 1）。抗原结构域A激发非病毒中和（非Vn）抗体和HVR 1激发 与病毒逃逸相关分离物特异性病毒中和（Vn）抗体。相反，抗原结构域 B、D和E引发在主要HCV基因型中更广泛为Vn的Vn抗体，并且它们的一些 表位与病毒逃逸无关。根据这些发现，以及最近的证据表明， 表位的构象稳定性是免疫原性的关键决定因素，以下问题将在 解决：增加抗原结构域D和E内Vn表位的构象稳定性 增加这些保守表位的免疫原性？非Vn抗原性结构域A表位可以是 沉默，以减少这些诱饵表位的免疫原性？我们将使用新的X射线 E2糖蛋白和与E2 Vn结合的人单克隆抗体的晶体学信息 表位，工程E2变体的免疫学表征，以解决这些问题。我们 目标是双重的。首先，我们将稳定抗原结构域E（Aim 1）和D（Aim 2）表位， 针对不同HCV基因型和亚型分离株的广泛病毒中和，并且与 病毒逃逸第二，我们将下调与非中和抗体相关的抗原结构域A表位。 作为免疫原性诱饵的抗体（目的3）。结构引导的计算建模将是 设计这些修改。将表征携带这些突变的E2变体 生物化学和免疫学上，随后评价它们在小鼠中诱导Vn抗体的能力。如果 这些研究将有助于开发一种合理设计的HCV疫苗， 广泛的Vn抗体来预防不同基因型和亚型的HCV感染。

The global burden of hepatitis C virus (HCV) infection is at 185 million with an annual rate of 3–4 million new infections each year. In the US, HCV infection is increasing in young adults because of injection drug use. A preventive vaccine is needed in spite of major advances in the development of direct acting antivirals (DAAs) for the treatment of HCV infections. Cumulative evidence has established that both T and B cell immunity contribute to the control of acute HCV infection. The focus of this application is on a B cell-based vaccine that has been technically challenging because of high variability in the viral envelope E1E2 glycoproteins, the natural target of protective antibodies. We have shown that the immunogenic regions on the E2 envelope glycoprotein of HCV segregate into five epitope clusters, designated antigenic domains A–E, and hypervariable region 1 (HVR1). Antigenic domain A elicits non-virus-neutralizing (non-Vn) antibodies and HVR1 elicits isolate-specific virus-neutralizing (Vn) antibodies associated with viral escape. By contrast, antigenic domains B, D, and E elicit Vn antibodies that are more broadly Vn among the major HCV genotypes, and some of their epitopes are not associated with viral escape. Based on these findings, and on recent evidence that the conformational stability of epitopes is a key determinant of immunogenicity, the following questions will be addressed: Does increasing the conformational stability of Vn epitopes within antigenic domains D and E increase the immunogenicity of these conserved epitopes? Can non-Vn antigenic domain A epitopes be silenced in order to decrease the immunogenicity of these decoy epitopes? We will use new X-ray crystallographic information on the E2 glycoprotein, and on human monoclonal antibodies bound to E2 Vn epitopes, to engineer E2 variants for immunological characterization to address these questions. Our objectives are two-fold. First, we will stabilize antigenic domain E (Aim 1) and D (Aim 2) epitopes that mediate broad virus neutralization against diverse HCV genotype and subtype isolates, and that are not associated with viral escape. Second, we will down-modulate antigenic domain A epitopes associated with non-neutralizing antibodies that serve as immunogenic decoys (Aim 3). Structure-guided computational modeling will be employed to design these modifications. E2 variants bearing these mutations will be characterized biochemically and immunologically, followed by evaluation of their capacity to induce Vn antibodies in mice. If successful, these studies will contribute to the development of a rationally designed HCV vaccine to induce broadly Vn antibodies to prevent HCV infection of different genotypes and subtypes.