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提供针对新出现的 流感病毒。开发“通用”疫苗的一种有吸引力的方法是， 靶向病毒表面上血凝素（HA）蛋白保守区域的抗体。的 受体结合位点和茎是两个这样的HA区域，并且体液反应的激发集中在 已经成为多项研究的主题。最近，一种新的抗体被发现， 发现靶向高度保守的HA头部三聚体界面。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性，并提供针对病毒的保护 动物模型的挑战因此，诱导这些类型的抗体作为通用流感病毒的一部分， 疫苗是有价值的。头部三聚体界面表位被封闭在HA的晶体结构中，并且 可能只是通过分子“呼吸”短暂暴露。这种有限的可访问性可以解释在 至少部分解释了为什么对这个部位的自然体液反应很少。在本提案中，我们将设计 在缺乏HA的分子背景下， 其他免疫显性位点。使用计算蛋白质建模和高通量文库筛选，HA 将开发衍生的以及基于非流感的免疫原，其：1）暴露HA头部三聚体 界面，以促进免疫识别; 2）优先与广泛交叉反应，但不与 菌株特异性抗体，靶向该位点和3）封闭免疫显性区域以集中免疫 表位上的反应。设计的免疫原将被用于给小动物接种疫苗，以评估它们的能力。 来抵御活病毒对接种动物的B细胞受体库的详细分析将揭示 导致体液反应激活和成熟的发育途径， 保守的HA头部三聚体界面。这一建议将提供候选免疫原的发展 一种通用流感疫苗，导致更好地了解控制HA的分子特征， 构象和免疫原性，并建立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.