"Extended dosing" immunization to enhance humoral immunity to next-generation vaccines

项目总结/摘要 大多数许可的疫苗被认为引起体液免疫介导的保护。一个关键 抗体反应的特异性和亲和力的决定因素是引发的生发中心（GC）反应 通过免疫，其中B细胞进入GC以经历循环的增殖和体细胞超突变 进化出更高亲和力的抗体，然后从GC中退出，成为长寿的浆细胞或记忆细胞。 B细胞。有效的GC反应被认为是关键的困难的病原体，如艾滋病毒，甚至是容易- 中和病毒，如SARS-CoV-2，有效和长寿命的GC反应与更多的 病毒变体的有效交叉中和。因此，优化GC反应是疫苗的基础 大致上在最近的工作中，我们研究了疫苗动力学-抗原和佐剂的时间模式 免疫过程中的暴露-影响体液免疫，特别是GC反应。我们的初步研究 已经揭示了在2 - 3周的时间内延长抗原向引流淋巴结的递送， 改变免疫反应一种特别有效的免疫方法，我们称之为"扩大免疫"， 给药"（下一次给药）免疫包括给予给定总剂量的疫苗抗原和佐剂 两周内注射六次剂量递增外剂量增加了 在小型和大型动物模型中，GC反应的增加并增加克隆性（不同B细胞的数量 参与GC的克隆），导致中和抗体产生增强。这些戏剧性的影响 下一剂量疫苗接种需要仔细研究，以了解这种策略是如何以及为什么如此有效。作为结束给药 通过重复注射对人类免疫是不切实际的，我们也有很高的动力来开发 替代策略，以实现相同的免疫效果，而不需要6次或更多次注射。到 为了实现这些目标，我们的具体目标是（1）确定抗原暴露动力学如何控制免疫 （2）确定佐剂暴露动力学如何影响免疫应答， （3）使用推注亚单位疫苗实现"延长剂量"效应的测试策略 施用，和（4）评估mRNA疫苗中外给药样效应的可能性。总之，这些 研究将阐明有效的初级免疫反应的基本概念，并开发新的 增强由亚单位和mRNA疫苗引起的免疫应答的预防相关方法。我们 使用临床相关抗原和佐剂对这些概念进行试验，并旨在寻求我们预期的策略 广泛适用于不依赖于疾病靶标的疫苗。

Project Summary/Abstract The majority of licensed vaccines are thought to elicit protection mediated by humoral immunity. A key determinant of the specificity and affinity of the antibody response is the germinal center (GC) response elicited by immunization, wherein B cells enter GCs to undergo cyclic rounds of proliferation and somatic hypermutation to evolve higher-affinity antibodies, followed by exit from the GC to become long-lived plasma cells or memory B cells. Effective GC responses are thought to be critical for difficult pathogens such as HIV, and even for easily- neutralized viruses such as SARS-CoV-2, effective and long-lived GC responses are associated with more effective cross-neutralization of viral variants. Hence, optimizing GC responses is fundamental to vaccines broadly. In recent work, we have studied how vaccine kinetics– the temporal pattern of antigen and adjuvant exposure during immunization– impact humoral immunity and GC reaction in particular. Our preliminary studies have revealed that prolonged delivery of antigen to draining lymph nodes over a period of 2-3 weeks substantially alters the immune response. One particularly effective immunization approach, which we term “extended dosing” (ext-dosing) immunization, involves administering a given total dose of vaccine antigen and adjuvant as a half-dozen injections over two weeks in an escalating-dose pattern. Ext-dosing enhances the magnitude of the GC response in both small and large animal models and increases the clonality (number of distinct B cell clones participating in the GC), leading to enhanced neutralizing antibody production. These dramatic effects of ext-dosing vaccination warrant close study to understand how and why this strategy is so effective. As ext-dosing through repeat injections is not practical for human immunization, we are also highly motivated to develop alternate strategies to achieve the same immunologic effects without the need for 6 or more injections. To address these goals, our specific aims are (1) define how antigen exposure kinetics govern the immune response elicited by ext-dosing immunization, (2) determine how adjuvant exposure kinetics impact the immune response in ext-dosing, (3) test strategies to achieve “extended-dosing” effects using bolus subunit vaccine administration, and (4) to evaluate the potential for ext-dosing-like effects in mRNA vaccines. Altogether, these studies will both clarify fundamental concepts underlying effective primary immune responses and develop new translationally-relevant approaches to enhance immune responses elicited by subunit and mRNA vaccines. We test-bed these concepts using clinically-relevant antigens and adjuvants, and aim to pursue strategies we expect to be broadly applicable to vaccines independent of disease target.