Rapid Response Vaccines for Botulinum Neurotoxins

描述(申请人提供)：肉毒杆菌神经毒素(BoNTs)是已知的最有效的蛋白质毒素。鉴于它们的强烈毒性和在生物战场景中的潜在用途，BoNTs被列入A类精选制剂。目前可用的五价类毒素疫苗需要多种增强剂才能有效，并且对不同的BONT血清型具有不同的保护作用。目前迫切需要一种BONT疫苗，在BONT暴露威胁迫在眉睫的情况下提供快速保护，并对多价疫苗的每一种成分提供有效的免疫反应。为了实现对HC的快速和更强大的免疫反应，我们一直在寻求将HC抗原连接到R4的策略，R4是我们开发的一种新型佐剂，可以有效地将疫苗抗原装载到树突状细胞(DC)上。通过将HC抗原特异性地靶向DC，加快了免疫反应的关键早期步骤。我们已经表达了ONT/A HC作为与R4的融合蛋白来产生HcR4，并且已经证明HcR4比单独使用HC抗原能够诱导对ONT/A HC抗原更快速和更强大的免疫反应。基于这些结果，我们推测可以利用HcR4融合蛋白开发出一种有效的针对BoNTs的快速有效的多价疫苗。该项目的目标是推进新型BONT疫苗的开发，这是对当前疫苗技术的重大改进。拟议的研究将通过开发B型和E型BONT的HcR4配体来实现这些目标，以便与已经生产和表征的作为多价疫苗的BONT/A HcR4结合使用。我们将测试这种多价疫苗作为单剂或多剂非肠道疫苗接种时，是否能够对BoNTs产生快速和保护性的免疫反应。此外，多价BONT疫苗将作为一种黏膜疫苗进行测试，以产生对BONT的系统和粘膜免疫反应。该项目将实现HcR4配体开发的下一个里程碑：1)我们将开发针对B型和E型BONT的HcR4免疫原，与已经开发和表征的BONT/A HcR4结合使用。2)我们将确定多价HcR4疫苗作为快速保护性、一次性疫苗和多剂量疫苗的有效性；以及3)确定粘膜/鼻腔注射HcR4是否可以快速诱导针对BoNTs的全身和粘膜抗体反应。这些研究旨在为推动多价BONT疫苗进入临床开发提供充分的原则证明。目前研究中获得的技术诀窍将有助于未来开发针对其他毒素和感染性病原体的新型和改进疫苗。 与公共卫生相关：迫切需要能够在暴露于毒素或其他生物制剂的威胁迫在眉睫的情况下提供快速保护的疫苗。为了生产快速有效的疫苗，我们开发了一种新型佐剂，它可以有效地将抗原靶向抗原呈递细胞。我们正在寻求使用这种佐剂来开发一种针对A型、B型和E型肉毒毒素的快速多价疫苗。

DESCRIPTION (provided by applicant): Botulinum neurotoxins (BoNTs) are the most potent protein toxins known. Given their potent toxicity and their potential use in bio-warfare scenarios, BoNTs are included among the Category A select agents. The currently available pentavalent toxoid vaccine requires multiple boosters before being effective, and protects unequally against the different BoNT serotypes. There is a critical need for BoNT vaccines that will induce rapid protection in situations where the threat of BoNT exposure is imminent as well as to provide effective immune responses to each constituent of a multivalent vaccine. To achieve rapid and more robust immune responses to Hc we have pursued a strategy of linking Hc antigens to R4, a novel adjuvant developed by us that efficiently loads vaccine antigens onto dendritic cells (DCs). By specifically targeting the Hc antigen to DCs, the critical early steps in the immune response are hastened. We have expressed BoNT/A Hc as a fusion protein with R4 to produce HcR4 and have demonstrated that HcR4 induces more rapid and robust immune responses to BoNT/A Hc antigen than can be achieved using the Hc antigen alone. Based on these results we hypothesize that an effective rapid- acting multivalent vaccine against BoNTs can be developed using HcR4 fusion proteins. The goal of this project is to advance the development of a new class of BoNT vaccines that represent a significant improvement over current vaccine technologies. The proposed studies will achieve these goals through development of HcR4 ligands for BoNT serotypes B and E for use in combination with the already produced and characterized BoNT/A HcR4 as a multivalent vaccine. We will test whether this multivalent vaccine can generate rapid and protective immune responses to BoNTs when administered as a single or multidose parenteral vaccine. In addition, the multivalent BoNT vaccine will be tested as a mucosal vaccine for the generation of systemic and mucosal immune responses to BoNT. This project will achieve the next milestones in the development of the HcR4 ligands: 1) We will develop HcR4 immunogens for BoNT serotypes B and E for use in combination with the already developed and characterized BoNT/A HcR4. 2) We will establish the efficacy of a multivalent HcR4 vaccine as a rapid- protection, one-shot vaccine, and as a multi-dose vaccine, and; 3) Determine if mucosal/nasal administration of HcR4 can result in the rapid induction of systemic and mucosal antibody responses against BoNTs. These studies are intended to deliver sufficient proof-of-principle for advancing the polyvalent BoNT vaccine into clinical development. The know-how gained in the current studies will be useful in the future for development of novel and improved vaccines to other toxins and infectious agents. PUBLIC HEALTH RELEVANCE: There is a critical need for vaccines that will induce rapid protection in situations where the threat of exposure to toxin or other biothreats is imminent. To produce rapid acting vaccines we have developed a novel adjuvant that efficiently targets antigen to antigen-presenting cells. We are seeking to use this adjuvant to develop a fast-acting multi-valent vaccine for Botulinum neurotoxin serotypes A, B, and E.