Elucidating the Structural Requirements for Next-Gen Glycoconjugate Vaccines

修改后的项目摘要/摘要部分 糖结合疫苗在全球范围内提供了巨大的健康益处，尽管它们在一些疾病高危人群(如老年人)中不太成功。在大多数情况下，糖抗原与载体蛋白的结合是经验性的，很少注意到对免疫反应至关重要的变量。我们实验室的最新发现为共轭化合物的工作原理提供了一个新的合理的解释。新的模型表明，由抗原呈递细胞向T细胞递送碳水化合物可能会极大地增强抗体反应的效力。将这一原理应用于B群链球菌病和图拉氏方济氏菌感染的小鼠模型中，通过使用载体肽而不是蛋白质，产生了比标准糖结合疫苗更具保护性的疫苗。我们还证明了多肽连接物和接合部位在提高接合效率和疫苗免疫应答中的关键作用。这些结果支持了这样的观点，即多肽糖结合疫苗对细菌挑战提供了更好的保护。值得注意的是，使用多肽而不是蛋白质作为载体，可以在碳水化合物特异性免疫球蛋白水平低得多的情况下提供更好的保护。这一观察结果挑战了糖结合物诱导的免疫球蛋白含量与保护作用之间直接相关的范式。对蛋白质和多肽糖偶联物产生的抗体和免疫细胞的全面评估将阐明使多肽疫苗非常有效的特征。我们将从免疫球蛋白G亚型、亲和力、亲和力和功能活性等方面评估糖肽疫苗的抗体反应，并阐明记忆B细胞上表达的共刺激/共抑制分子，并将其与正在制造的抗体的功能联系起来。最后，我们将使用蛋白质组学方法定义MHCII抗原提呈分子和辅助T细胞受体之间的相互作用。重组TCR将被用来从结构上定义与糖肽表位的相互作用。我们的方法将确定使糖肽诱导的抗体如此有效的特征。我们将应用我们对这些多肽/多糖结合物的研究来创造对糖结合物疫苗更有效和更持久的免疫。

Modified Project Summary/Abstract Section Glycoconjugate vaccines provide enormous health benefits globally, although they have been less successful in some populations at high risk for developing disease, such as the elderly. In most cases, conjugation of the sugar antigen to the carrier protein has been done empirically with little attention paid to variables critical for the immune response. Recent findings from our lab offer a new and rational explanation for how conjugates work. The new model suggests that carbohydrate presentation to T cells by antigen-presenting cells may strongly enhance the efficacy of antibody responses. Application of this principle in mouse models of group B streptococcal disease and Francisella tularensis infection by using a carrier peptide rather than a protein, resulted in vaccines more protective than standard glycoconjugate vaccines. We have also demonstrated the critical role of the peptide linker and the conjugation site in enhancing both the conjugation efficiency and the immune response to vaccines. The results support the notion that peptide glycoconjugate vaccines provide superior protection against bacterial challenges. Remarkably, the use of a peptide instead of a protein as a carrier confers better protection at much lower levels of carbohydrate specific IgG. This observation challenges the paradigm of a direct correlation between the amount of IgG induced by a glycoconjugate and protection. A comprehensive evaluation of antibodies and immune cells generated by protein vs. peptide glycoconjugates will clarify the features that make peptide vaccines extremely potent. We will evaluate the antibody response to glycopeptide vaccines in terms of IgG subtypes, affinity, avidity and functional activity, and elucidate the costimulatory/coinhibitory molecules being expressed on memory B cells and relate this to the functionality of the antibodies being made. Finally, we will define the interactions between the MHCII antigen presentation molecule and the helper T cell receptor using a proteomic approach. Recombinant TCRs will be used to structurally define the interactions with glycopeptide epitopes. Our approach will identify the characteristics that make glycopeptide-induced antibodies so potent. We will apply our studies of these peptide/polysaccharide conjugates to create more efficacious and longer lasting immunity to glycoconjugate vaccines.