Structure-Based Design of a Broadly Protective Group A Streptococcal Vaccine

这个项目的总体目标是开发一种安全、广泛有效和负担得起的疫苗来预防群体性疾病 一种链球菌感染。抗M表面N-末端高变区的抗体 GAS的蛋白质是调控性的，与预防感染有关。豁免权在传统上 被描述为“特定类型的”，从而导致假设自然免疫提供了对 只有200多种不同类型的EMM气体中的一种。我们现在有了新的信息，可以调用 质疑这一经典观点，并作为一种完全不同的气体疫苗设计和方法的基础 发展。全球175个EMM中M蛋白的最新综合序列分析 天然气类型导致了一个新的EMM分类系统，该系统对当代所有天然气进行了96.2%的分类 分离到48个EMM簇，包含结构和功能相关的M蛋白。此外，117个emm 16个聚类群的类型占全球GAS感染的94.4%。事实上，临床前研究 表明含有来自30个流行M型的N末端多肽的多价疫苗具有交叉调理作用 与疫苗EMM类型共存的大量非疫苗EMM类型的气体。 交叉调理抗体的频率，结合EMM集群数据，促使我们得出结论 有必要改变针对气体感染的“特定类型”免疫力的概念。 一种“特定于星团的”免疫力。我们的总体假设是对气体感染的免疫力是 针对M蛋白N末端区域的类型特异性和交叉反应抗体，以及一种新的 使用多肽结构计算预测的方法将产生一种多价疫苗，它将 在世界各地的人群中诱导广泛的保护性免疫。我们的初步结果表明 使用基于结构的设计来预测簇内M多肽的抗原相关性的可行性。 该建议的具体目标是：1)在迭代过程中应用基于计算结构的设计 使用来自目标2的免疫学数据来预测最多的M肽序列的最小数量 代表包含在一个EMM簇中的肽的结构和物理化学性质 17种GAS EMM类型，2)确定所选择的多肽与所有 星团中17种EMM气体，并将结果应用于改进计算设计 目标1、3)中的预测应用目标1和目标2的精细化计算参数来分析 其余具有重要流行病学意义的肌萎缩侧索硬化症簇，选择一组代表所有 EMM类型，构建四种多价重组疫苗蛋白，并评估潜在的交叉保护 使用体外杀菌试验对所有117种emm类型的GAS进行免疫原性测定，以及4)确定 最终多价疫苗在表达人C4BP的转基因小鼠中的保护性免疫原性 和因子H，将被免疫，然后用多种EMM类型的GAS进行挑战。

The overall goal of this project is to develop a safe, broadly effective, and affordable vaccine to prevent group A streptococcal infections. Antibodies against the N-terminal hypervariable region (HVR) of surface M (Emm) proteins of GAS are opsonic and are associated with protection against infection. Immunity has classically been described as “type-specific”, leading to the assumption that natural immunity confers protection against only one of the more than 200 different emm types of GAS. We now have new information that calls into question this classic view and serves as the basis for an entirely different approach to GAS vaccine design and development. A recent comprehensive sequence analysis of M proteins from a global collection of 175 emm types of GAS resulted in a new emm cluster typing system that classified 96.2% of all contemporary GAS isolates into 48 emm clusters containing structurally and functionally related M proteins. Moreover, 117 emm types contained in 16 clusters accounted for 94.4% of GAS infections in the world. Indeed, preclinical studies indicated that a multivalent vaccine containing N-terminal peptides from 30 prevalent M types cross-opsonized a significant number of non-vaccine emm types of GAS that co-localized in clusters with vaccine emm types. The frequency of cross-opsonic antibodies, combined with the emm cluster data, prompted us to conclude that there is a need for a paradigm shift away from the concept of “type-specific” immunity against GAS infections to one of “cluster-specific” immunity. Our overall hypothesis is that immunity to GAS infections is the result of both type-specific and cross-reactive antibodies against the N-terminal regions of M proteins and that a new approach employing computational predictions of peptide structures will result in a multivalent vaccine that will induce broadly protective immunity in populations throughout the world. Our preliminary results indicate the feasibility of using structure-based design to predict the antigenic relatedness of M peptides within a cluster. The specific aims of this proposal are to: 1) Apply computational structure-based design in an iterative process with immunological data from Aim 2 to predict the minimal number of M peptide sequences that are most representative of the structural and physicochemical properties of the peptides in one emm cluster containing 17 GAS emm types, 2) determine the cross-reactive immunogenicity of the selected peptides with all seventeen emm types of GAS in the cluster, and apply the results to refine the computational design predictions in Aim 1, 3) apply the refined computational parameters from Aims 1 and 2 to analyze the remaining epidemiologically important emm clusters, select a comprehensive panel of peptides representing all emm types, construct four multivalent recombinant vaccine proteins, and assess potential cross-protective immunogenicity using in vitro bactericidal assays against all 117 emm types of GAS, and 4) determine the protective immunogenicity of the final multivalent vaccine in unique transgenic mice expressing human C4BP and factor H that will be immunized and then challenged with multiple emm types of GAS.