Rapid Response Vaccines for Botulinum Neurotoxins

描述（由申请人提供）：肉毒神经毒素（BoNT）是已知最有效的蛋白质毒素。鉴于其强大的毒性和在生物战场景中的潜在用途，BoNT被列入A类选择剂。目前可用的五价类毒素疫苗在有效之前需要多个加强剂，并且对不同BoNT血清型的保护不平等。 迫切需要BoNT疫苗，其将在BoNT暴露的威胁迫在眉睫的情况下诱导快速保护，以及对多价疫苗的每种成分提供有效的免疫应答。为了实现对Hc的快速和更稳健的免疫应答，我们已经追求将Hc抗原与R4连接的策略，R4是我们开发的一种新型佐剂，其有效地将疫苗抗原加载到树突状细胞（DC）上。通过将Hc抗原特异性靶向DC，免疫应答中的关键早期步骤被加速。我们已经表达了BoNT/AHc作为与R4的融合蛋白以产生HcR 4，并且已经证明HcR 4诱导对BoNT/AHc抗原的比单独使用Hc抗原可以实现的更快速和更稳健的免疫应答。基于这些结果，我们假设可以使用HcR 4融合蛋白开发针对BoNT的有效快速作用的多价疫苗。 该项目的目标是推进一类新的BoNT疫苗的开发，这代表了对当前疫苗技术的重大改进。所提出的研究将通过开发BoNT血清型B和E的HcR 4配体来实现这些目标，所述配体与已经生产和表征的BoNT/A HcR 4组合用作多价疫苗。我们将测试这种多价疫苗作为单剂量或多剂量胃肠外疫苗给药时是否能对BoNT产生快速和保护性免疫应答。此外，多价BoNT疫苗将作为粘膜疫苗进行测试，以产生对BoNT的全身和粘膜免疫应答。 该项目将实现HcR 4配体开发的下一个里程碑：1）我们将开发BoNT血清型B和E的HcR 4免疫原，用于与已经开发和表征的BoNT/A HcR 4组合使用。2)我们将确定多价HcR 4疫苗作为快速保护、一次性疫苗和作为多剂量疫苗的功效，以及; 3）确定HcR 4的粘膜/鼻施用是否可以导致针对BoNT的全身和粘膜抗体应答的快速诱导。 这些研究旨在为推进多价BoNT疫苗进入临床开发提供充分的原理证明。目前研究中获得的知识将在未来用于开发针对其他毒素和感染因子的新型和改进疫苗。 公共卫生相关性：在暴露于毒素或其他生物威胁的威胁迫在眉睫的情况下，迫切需要能够引起快速保护的疫苗。为了生产快速作用的疫苗，我们开发了一种新的佐剂，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针对肉毒杆菌神经毒素血清型A、B和E的快速作用的多价疫苗。

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.