Shifting immunodominance of humoral immunity against influenza viruses

项目总结 流感病毒仍然是对人类健康的重大全球威胁，由于缺乏有效的 疫苗。体液免疫并不是均匀地针对病毒的所有部分，这种现象被称为 免疫优势。在季节性疫苗接种后，人类优先产生抗体反应 血凝素(HA)头部区域的不断演变的表位，而不是针对广泛保护的 保守的茎域。在缺乏针对医管局局长的先前存在的豁免权的情况下，如2009年发生的那样 大流行H1N1病毒，人类可以优先召回针对茎结构域的记忆B细胞。然而，天真 针对HA头的新表位的B细胞被诱导，填充到记忆B细胞池，并被 在接触到抗原性相似的病毒后优先回忆起。因此，免疫优势 Head结构域和针对新表位的幼稚B细胞的优先招募仍然是 产生一种具有广泛保护性的流感疫苗。为了产生广泛的保护性体液 免疫，需要设计一种疫苗来诱导针对茎的强大和持久的抗体反应 但阻止针对新表位的幼稚B细胞的招募。 免疫优势在一定程度上取决于B细胞能够获得抗原并有效地将抗原呈递给CD4 T细胞。B细胞亲和力，一种抗体的两个结合部位与其表位的同时结合，以及与B细胞的交叉结合。 B细胞上多个B细胞受体的连接在选择B细胞特异性方面起着至关重要的作用。B类 针对头部结构域的细胞具有亲和力优势，因为这些表位比那些 茎域。我们假设，降低B细胞对头部表位的亲和力将减少竞争 抗原，限制抗头B细胞的诱导，并优先选择针对茎结构域的B细胞。 利用组合诱变和酵母展示技术，我们将产生并筛选一个稳定的Has文库 不同的头部表位但有相同的茎结构域，我们称之为杂乱的HA(目标1)。通过滴定 多样性的扰乱，我们将确定增加头部表位多样性对B和T的影响 诱导卵泡辅助细胞的特异性。我们将在幼稚和甲流免疫中进行这些实验 让小鼠分别模拟婴儿和成人的免疫史(目标2)。此外，我们将为人类接种疫苗 从不同免疫史的人身上产生的体外淋巴结类有机化合物来确定我们的 方法召回针对茎结构域的记忆B细胞(目标3)。总之，这项研究将产生一种疫苗 这将免疫优势转移到茎结构域，这将通过多种先前存在的模型得到证实。 豁免权。虽然这项提议的重点是改变抗流感体液免疫的免疫主导地位，但 所采取的方法提供了一种概念证明，可以应用于其他快速进化的病原体 免疫优势是成功研制疫苗的关键障碍，包括艾滋病毒和冠状病毒。

PROJECT SUMMARY Influenza viruses remain a major global threat to human health, which is exacerbated by the lack of an effective vaccine. Humoral immunity does not target all parts of the virus evenly, a phenomenon known as immunodominance. Following seasonal vaccination, humans preferentially generate antibody responses against evolving epitopes of the hemagglutinin (HA) head domain rather than against broadly protective epitopes of the conserved stalk domain. In the absence of preexisting immunity against the HA head, as occurred with the 2009 pandemic H1N1 virus, humans can preferentially recall memory B cells against the stalk domain. However, naïve B cells against novel epitopes of the HA head are induced, populate the memory B cell pool, and are preferentially recalled following exposure to an antigenically similar virus. Therefore, immunodominance of the head domain and the preferential recruitment of naïve B cells against new epitopes remains a major obstacle for the generation of a broadly protective influenza vaccine. In order to generate broadly protective humoral immunity, a vaccine needs to be designed that induces robust and durable antibody responses against the stalk domain but prevents the recruitment of naïve B cells against neoepitopes. Immunodominance is in part dictated by which B cells can acquire antigen and efficiently present antigen to CD4 T cells. B cell avidity, the simultaneous binding of both binding-sites of an antibody with its epitope and the cross- linking of multiple B cell receptors on a B cells, plays a critical role in which B cell specificities are selected. B cells against the head domain have an avidity advantage, as these epitopes are more accessible than those of the stalk domain. We hypothesize that reducing B cell avidity for head epitopes will reduce competition for antigen, limit the induction of anti-head B cells, and preferentially select for B cells against the stalk domain. Using combinatorial mutagenesis and yeast-display, we will generate and select for a library of stable HAs with diverse head epitopes but an identical stalk domain, which we refer to as scrambled HA (Aim 1). By titrating the diversity of scrambled HAs, we will determine the effect of increasing head epitope diversity on which B and T follicular helper cell specificities are induced. We will perform these experiments in naïve and H1N1 immune mice to mimic immune histories in infants and adults, respectively (Aim 2). Moreover, we will immunize human ex vivo lymph node organoids generated from individuals of diverse immune histories to determine if our approach recalls memory B cells against the stalk domain (Aim 3). Together, this study will generate a vaccine that shifts immunodominance towards the stalk domain, which will be proven using multiple models of preexisting immunity. Although this proposal focuses on shifting immunodominance of anti-influenza humoral immunity, the approach taken provides a proof-of-concept that can be applied to other rapidly evolving pathogens for which immunodominance is a key barrier for successful vaccine generation, including HIV and coronaviruses.