Structural interrogation of vaccine- and infection-induced B cell responses

疫苗和感染诱导的 B 细胞反应的结构研究

• 批准号: 10577857
• 负责人: Goran Bajic
• 金额: $ 78.27万
• 依托单位: ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-02-22 至 2027-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10577857
• 关键词: 2019-nCoV; Affect; Animal Model; Antibodies; Antibody Affinity; Antibody Repertoire; Antibody Response; Antibody Specificity; Antibody-mediated protection; Antigenic Variation; Antigens; Antiviral Response; B cell repertoire; B-Lymphocytes; Binding; Biochemical; Biological Assay; Blood Cells; COVID-19 vaccination; COVID-19 vaccine; Cell Compartmentation; Cells; Cellular biology; Complex; Containment; Coronavirus; Cryoelectron Microscopy; Data; Dimensions; Epitopes; Evolution; Exposure to; Frequencies; Genes; Genetic; Goals; Health; Human; Immune; Immune Evasion; Immune response; Immune system; Immunity; Immunization; Immunodominant Epitopes; Immunoglobulin Somatic Hypermutation; Immunologic Memory; Immunology; Individual; Infection; Influenza; Maps; Membrane Glycoproteins; Memory B-Lymphocyte; Modeling; Molecular; Monoclonal Antibodies; Mutate; Mutation; N-terminal; Plasmablast; Population; Primary Infection; Proteins; RNA vaccine; Reaction; Research; SARS-CoV-2 spike protein; SARS-CoV-2 variant; Sampling; Seasons; Specificity; Structure; Structure of germinal center of lymph node; Time; Tissues; Vaccination; Vaccine Antigen; Vaccine Design; Vaccinee; Vaccines; Variant; Viral; Virus; Visualization; adaptive immune response; arms race; breakthrough infection; cross reactivity; design; draining lymph node; imprint; influenzavirus; insight; longitudinal analysis; memory recall; novel; novel vaccines; pathogen; pathogenic virus; protein structure; receptor binding; recurrent infection; response; seasonal coronavirus; structural biology; translation to humans; vaccination strategy; vaccine formulation; vaccine trial; vaccine-induced antibodies; vaccinology; variants of concern

Immunodominance, the observation that epitopes on an antigen are not “born equal”, poses a major challenge for next-generation vaccines against rapidly evolving pathogens. An underlying premise of this proposal is that in order to engage in rational immunogen design for next-generation vaccines, we first need to answer a fundamental question in immunology -- namely how to define immunodominance in biochemical and structural terms. Rather than relying on animal models that could complicate the direct translation to human health, we will directly sample both the circulating (plasmablasts and memory B cells) and tissue-resident (germinal center) B cells in humans. First, we will use structural biology approaches – primarily cryo-EM – to ask what an immunodominance map of an initial immunization looks like on a protein structure level (Aim 1). Specifically, we will establish epitopic heatmaps of antigen-specific B cells after vaccination in humans, using SARS-CoV-2 spike glycoprotein as a model antigen. Studies with other viruses like influenza have shown that pre-existing immunity generated upon primary infection biases all subsequent immune responses (to infection and to vaccination). In influenza, the issue is the immunodominance of epitopes that readily mutate (antigenic drift) and make the seasonal reformulation of the vaccine required. In our recent study of vaccination against SARS-CoV-2, we noted an original antigenic sin-like backboost to the spikes of two seasonal human coronaviruses OC43 and HKU1. Antibodies derived from the cross-reactive B cells had higher levels of mutation than did the strain-specific ones. We therefore wish to know how pre-existing immunity, generated by preceding infection, affects immunological memory and de novo responses to subsequent vaccination (Aim 2). We will follow the maturation of immune responses longitudinally. We will a) determine the somatic genetic relationships among responding B cells during primary and recall responses b) examine the resulting antibody (Ab) specificity and affinity maturation and c) follow the evolution of immunodominance heatmaps over time across B cell compartments. Recent emergence of SARS-CoV-2 variants of concern (VOCs) has made it clear that the virus mutates to avoid immune responses on a population level. However, how much antigenic variation is allowed so that there is still vaccine protection against different variants is unknown. We will concurrently follow the B responses “breakthrough infections” and sequence the infecting strain to understand the epitopic distance that permits reinfection (Aim 3). The overarching goal of this proposal is to understand the structural features of immune imprinting and, ultimately, the structural correlates of Ab protection against evolving viruses. Insights gained will not only shed light on the basic B cell biology but will also inform better vaccines. We will use SARS-CoV-2 as a model but we will extend to other coronaviruses as probes of the immune system's ability to mount an appropriate antiviral response. A particular strength of this proposal is the use of structural biology to gain atomic level, mechanistic understanding of the evolution of the Ab response with direct, single-cell interrogation of B cell responses in humans.

免疫优势，即观察到抗原上的表位并不“生来平等”，构成了一个重大挑战。 针对快速进化的病原体的下一代疫苗。这项提议的一个基本前提是 为了从事下一代疫苗的合理免疫原设计，我们首先需要回答一个 免疫学的基本问题--即如何界定生化和结构上的免疫优势 条款。与其依赖动物模型，这可能会使直接转化为人类健康的过程复杂化，我们将 直接采样循环(浆母细胞和记忆B细胞)和组织驻留(生发中心)B细胞 人类体内的细胞。首先，我们将使用结构生物学方法-主要是低温EM-来询问 初始免疫的免疫优势图看起来像是在蛋白质结构水平上(目标1)。具体来说，我们 将使用SARS-CoV-2尖峰在人类接种后建立抗原特异性B细胞的表位热图 糖蛋白作为模型抗原。对流感等其他病毒的研究表明，先前存在的免疫力 初次感染时产生的病毒偏向所有随后的免疫反应(对感染和疫苗接种)。在……里面 对于流感，问题是容易突变(抗原漂移)的表位的免疫优势，并使 需要对疫苗进行季节性重新配制。在我们最近对SARS-CoV-2疫苗接种的研究中，我们注意到 对两种季节性人类冠状病毒OC43和HKU1的尖峰的原始抗原性类SIN反推。 来自交叉反应的B细胞的抗体比菌株特异性的抗体有更高的突变水平。 因此，我们希望知道先前感染产生的先前存在的免疫如何影响免疫学。 对后续疫苗接种的记忆和从头反应(目标2)。我们将跟随免疫的成熟 纵向上的反应。我们将a)确定在反应的B细胞之间的体细胞遗传关系 初步反应和召回反应b)检查所产生的抗体(Ab)的特异性和亲和力成熟度以及c) 跟踪B细胞隔间免疫优势热图随时间的演变。新近崛起 SARS-CoV-2令人担忧的变种(VOCs)的研究表明，病毒变异是为了避免免疫反应 在人口层面上。然而，允许多少抗原变异才能仍有疫苗保护 对不同的变种的作用尚不清楚。我们将同时关注B类应对措施“突破性感染”和 对感染菌株进行测序，以了解允许再次感染的表位距离(目标3)。这个 这项提议的首要目标是了解免疫印记的结构特征，并最终， 针对进化病毒的抗体保护的结构相关性。所获得的见解不仅将揭示 基本的B细胞生物学，但也将提供更好的疫苗。我们将使用SARS-CoV-2作为模型，但我们将扩展 以其他冠状病毒为探针，检测免疫系统产生适当的抗病毒反应的能力。一个 这一提议的特别优点是使用结构生物学来获得原子水平的机械论理解 通过对人类B细胞反应的直接、单细胞询问，研究抗体反应的进化。