Development of germline-targeting HCV E2 immunogens to drive neutralizing antibody evolution

开发种系靶向 HCV E2 免疫原以驱动中和抗体进化

• 批准号: 436187515
• 负责人: Professor Dr. Thomas Krey
• 金额: --
• 依托单位: Institut für Biochemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2020
• 资助国家: 德国
• 起止时间: 2019-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/436187515?language=en
• 关键词: Development; germline; targeting; HCV; E2

Chronic infection by the hepatitis C virus (HCV) is associated with severe liver disease including hepatocellular carcinoma and it has become one of the leading causes for liver transplantation. Recently licensed antiviral combination therapies reach cure rates greater than 95%. However, treatment is costly and does not protect from viral re-infection. Moreover, many patients are not diagnosed and unaware of their infection, and virus transmission remains high. Therefore, the development of a prophylactic HCV vaccine is an unmet medical need. Accumulating evidence underpins the importance of neutralizing antibodies for the clearance of HCV during natural infection. Notably, 20-30% of exposed individuals naturally clear the infection and neutralizing antibodies can be triggered by immunization, raising hopes that a prophylactic HCV vaccine can be developed. However, the induced antibody responses in serum are usually modest with regard to breadth and potency, although broadly neutralizing monoclonal human and murine antibodies (bnAbs) with high potency have been identified. Such bnAbs develop from the so-called inferred germline B cell receptor (iGL BCR) via somatic hypermutation of the antigen-binding regions in a long process that requires clonal selection and affinity maturation for an optimized fine-tuning of the antibody-antigen interaction. Sequence analysis of numerous bnAbs targeting HCV glycoproteins revealed that few somatic mutations are required for affinity maturation, indicating that the usage of so-called germline-targeting immunogens, i.e., engineered immunogens targeting a specific iGL BCR, could potentiate the induction of bnAbs. The goal of this project is therefore to provide the proof-of-concept that usage of such engineered germline-targeting immunogens results in an enhanced development of the respective bnAb and potentially an increased neutralization capacity of serum. We will develop recombinant HCV glycoproteins into germline-targeting immunogens that bind to iGL BCR with higher affinity and therefore have a higher capacity to stimulate the corresponding B cells. For this purpose we will use in parallel 1) a structure-based protein engineering strategy and 2) a library-based surface display strategy. We will investigate the immunogenicity of the resulting immunogens in a recently developed transgenic humanized mouse model that produces human antibodies (Erlanger mighty mouse antibody platform; EMMA). These mice will allow us to follow antibody maturation by single cell B cell sequencing and therefore assess the impact of individual immunogens on the development of bnAbs.Our results will contribute to a better understanding of the interplay between HCV and the human immune system as well as the manipulability of the latter by targeted stimulation of certain B cell populations. They will therefore pave the way for the development of a novel prophylactic and therapeutic vaccine to combat HCV infection.

丙型肝炎病毒的慢性感染与包括肝细胞癌在内的严重肝病有关，已成为肝移植的主要原因之一。最近获得许可的抗病毒联合疗法的治愈率超过95%。然而，治疗费用高昂，而且不能防止病毒再次感染。此外，许多患者没有得到诊断，也没有意识到他们的感染，病毒传播率仍然很高。因此，开发预防性丙型肝炎疫苗是一项尚未得到满足的医学需求。越来越多的证据支持了在自然感染期间中和抗体对清除丙型肝炎病毒的重要性。值得注意的是，20%-30%的暴露者自然清除了感染和中和抗体，免疫可以触发，这增加了开发预防性丙型肝炎疫苗的希望。然而，尽管已经鉴定出具有广泛中和能力的人和鼠抗体(BNAbs)，但在血清中诱导的抗体反应在广泛性和效价方面通常是温和的。这类bNAbs由所谓的推测生殖系B细胞受体(IGL BCR)通过抗原结合区的体细胞超突变发展而来，这需要克隆选择和亲和力成熟来优化抗体-抗原相互作用的微调。对大量针对丙型肝炎病毒糖蛋白的bNAbs的序列分析表明，亲和力成熟所需的体细胞突变很少，这表明使用所谓的种系靶向免疫原，即针对特定IGL BCR的工程免疫原，可以增强bNAbs的诱导。因此，该项目的目标是提供概念证明，即使用这种工程生殖系靶向免疫原可以促进相应bNab的发展，并潜在地提高血清的中和能力。我们将把重组的丙型肝炎病毒糖蛋白开发成种系靶向免疫原，以更高的亲和力与IGL BCR结合，从而具有更高的刺激相应B细胞的能力。为此，我们将同时使用1)基于结构的蛋白质工程策略和2)基于库的表面展示策略。我们将在最近开发的产生人类抗体的转基因人源化小鼠模型(Erlanger强大的小鼠抗体平台；Emma)中研究所产生的免疫原的免疫原性。这些小鼠将允许我们通过单细胞B细胞测序来跟踪抗体的成熟情况，从而评估单个免疫原对bnAbs发育的影响。我们的结果将有助于更好地理解丙型肝炎病毒和人类免疫系统之间的相互作用，以及后者通过靶向刺激某些B细胞群体来操纵的可能性。因此，它们将为开发一种新的预防和治疗性疫苗来对抗丙型肝炎病毒感染铺平道路。