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

项目摘要/摘要 大多数获得许可的疫苗被认为是通过体液免疫来获得保护的。一把钥匙 抗体反应的特异性和亲和力的决定因素是所引起的生发中心(GC)反应 通过免疫，其中B细胞进入GC经历周期性的几轮增殖和体细胞超突变 进化出亲和力更高的抗体，然后退出GC，成为长寿的浆细胞或记忆细胞 B细胞。有效的GC反应被认为对艾滋病毒等疑难病原体至关重要，甚至对容易感染的病原体也是如此。 中和病毒，如SARS-CoV-2，有效和长期的GC反应与更多 有效的病毒变种的交叉中和。因此，优化GC响应是疫苗的基础 大体上说。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 免疫期间暴露--影响体液免疫，特别是GC反应。我们的初步研究 有研究表明，在2-3周的时间内将抗原延长到引流淋巴中的时间大大增加 改变免疫反应。一种特别有效的免疫方法，我们称之为“扩展的 剂量“(外部剂量)免疫，包括给予给定的疫苗抗原和佐剂的总剂量 在两周内以递增的剂量模式进行六次注射。超量服用提高了药效。 在小动物和大动物模型中的GC反应，并增加克隆性(不同的B细胞的数量 参与GC的克隆)，导致增强中和抗体的产生。这些戏剧性的效果 额外剂量的疫苗接种需要仔细研究，以了解这一策略如何以及为什么如此有效。作为超量服用 通过重复注射对人类免疫是不现实的，我们也有很高的发展动力 不需要6次或更多注射即可达到相同免疫效果的替代策略。至 为了达到这些目标，我们的具体目标是：(1)确定抗原暴露动力学如何支配免疫 超剂量免疫引起的反应，(2)确定佐剂暴露动力学如何影响免疫 超量接种中的反应，(3)使用团注亚单位疫苗实现“超量接种”效果的测试策略 给药，以及(4)评估在信使核糖核酸疫苗中外加剂量类效应的可能性。总而言之，这些 研究将澄清有效的初级免疫反应背后的基本概念，并开发新的 增强亚单位疫苗和信使核糖核酸疫苗引起的免疫反应的翻译相关方法。我们 使用与临床相关的抗原和佐剂来测试这些概念，并旨在实施我们预期的策略 广泛适用于与疾病目标无关的疫苗。

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.