Novel Immunogens to Elicit Broadly Cross-reactive Antibodies That Target the Hemagglutinin Head Trimer Interface

摘要 需要具有更高效力并对新出现的疾病提供长期保护的新型疫苗。 流感病毒。开发一种“通用”疫苗的一种有吸引力的方法是专注于诱导 针对病毒表面血凝素(HA)蛋白保守区的抗体。这个 受体结合部位和茎是两个这样的HA区域，体液反应的激发是重点 在这些网站上一直是多项研究的主题。最近，一类新的抗体被发现 发现了以高度保守的HA头三聚体界面为靶点的。针对该表位的抗体是 在多个个体中发现，具有广泛的异亚型交叉反应，并提供对病毒的保护 动物模型中的挑战。因此，诱导这些类型的抗体是普遍流感的一部分 疫苗将是有价值的。头三聚体界面表位被封闭在HAS的晶体结构中，并且 很可能只是通过分子“呼吸”瞬间暴露出来。这种有限的可访问性可能解释了 至少在一定程度上，为什么针对这个网站的自然体液反应很少。在这份提案中，我们将设计 在分子环境中呈现畅通的HA头三聚体界面表位的免疫原 其他免疫优势部位。使用计算蛋白质建模和高通量文库筛选，HA 将开发衍生的和非流感为基础的免疫原，以：1)暴露HA头部三聚体 接口，以促进免疫识别；2)优先与广泛的交叉反应相互作用，但不与 针对这一部位的菌株特异性抗体和3)封闭免疫优势区域以集中免疫 对表位的反应。设计的免疫原将被用来为小动物接种疫苗，以评估它们的能力 以防止活病毒的传播。对接种疫苗的动物的B细胞受体谱系的详细分析将揭示 导致体液免疫反应激活和成熟的发育途径 保守的HA头三聚体界面。这项提议将为发展提供候选免疫原。 对通用流感疫苗的研究，有助于更好地了解控制HA的分子特征 构象和免疫原性，并建立了免疫原设计的一般方法。

Abstract Novel vaccines are needed that have higher efficacy and that provide long-lasting protection against emerging influenza viruses. An attractive approach towards developing a “universal” vaccine is focused on eliciting antibodies that target conserved regions of the hemagglutinin (HA) protein on the surface of the virus. The receptor binding site and the stem are two such HA regions, and the elicitation of humoral responses focused on these sites has been the subject of multiple studies. Recently, a new class of antibodies has been discovered that targets the highly conserved HA head trimer interface. Antibodies against this epitope were found in multiple individuals, have broad heterosubtypic cross-reactivity and provided protection against viral challenges in animal models. Therefore, induction of these type of antibodies as part of a universal influenza vaccine would be valuable. The head trimer interface epitope is occluded in crystal structures of HAs, and likely becomes exposed just transiently through molecular “breathing”. This limited accessibility may explain at least in part why natural humoral responses against this site are rare. In this proposal, we will engineer immunogens that present unobstructed the HA head trimer interface epitope in molecular contexts devoid of other immunodominant sites. Using computational protein modeling and high throughput library screening, HA derived as well as non-influenza based immunogens will be developed that: 1) expose the HA head trimer interface to facilitate immune recognition; 2) preferentially interact with broadly cross-reactive, but not with strain specific, antibodies that target this site and 3) occlude immunodominant regions to focus the immune responses on the epitope. Designed immunogens will be used to vaccinate small animals to assess their ability to protect against live virus. Detailed analysis of the B cell receptor repertoires of vaccinated animals will reveal the developmental pathways that lead to the activation and maturation of humoral responses against the conserved HA head trimer interface. This proposal will provide candidate immunogen towards the development of a universal influenza vaccine, lead to a better understanding of molecular features that control HA conformation and immunogenicity, and establish general approaches for immunogen design.