VACCINE: Defining signature responses at the innate-adaptive interface to inform the design of vaccines inducing cellular immunity

通过接种疫苗预防和控制传染病对全世界养殖动物的生产力和福利至关重要，对维护全球粮食安全也是必要的。然而，对于许多流行的疾病，特别是那些免疫需要细胞介导的反应的疾病，有效的可部署疫苗是可用的，事实证明，开发这些疫苗极具挑战性。此外，目前筛选候选疫苗的方法包括给动物接种疫苗，然后进行疾病挑战以测试免疫力。这既冗长又昂贵，而且往往无法深入了解某一特定疫苗失败的原因。我们的目标是通过识别与启动保护性免疫反应相关的早期免疫反应的特征来产生新的工具来解决这些问题。这一过程的中心是被称为树突状细胞(DC)的特殊细胞。DC存在于周围组织(包括皮肤)中，一旦遇到病原体或疫苗，就会通过淋巴管迁移到淋巴结。它们携带有关病原体/疫苗性质的抗原和信号，它们一起用来启动适当的免疫反应。DC刺激全功能免疫反应的能力似乎严重依赖于它在组织中遇到病原体/疫苗时收到的信号的性质。然而，这些进程的位置使其极难访问和研究。我们已经在一个模型系统(淋巴管插管)方面建立了专业知识，该系统允许我们在牛犊与病原体/疫苗相互作用后，在牛犊从皮肤中排出时收集大量DC。这提供了一个独特的机会，在自然环境中研究免疫反应的这一关键早期阶段，这在其他物种中是不可能的。在这个项目中，我们将收集DC，在给药之前和之后立即进行实验室分析，选择的基础是活的病原体激发可预测的和描述良好的免疫反应。然后，我们将使用一系列技术来调查DC对这些病原体的反应，包括最近开发的测序工具，这些工具提供了发生过程的详细解析，在这方面我们有更多的专业知识。我们将重点定义对不同类别病原体(细菌、寄生虫和病毒)的反应，这些反应是根据预期它们在DC中产生不同的反应而选择的。我们的目标是定义DC内发生的使其能够诱导免疫的过程(与未诱导免疫时发生的过程相反)。这将为我们提供“签名”，可用作评估疫苗诱导的反应的基础，以期在未来旨在生产新的/改进的疫苗的研究中。从这些“签名”中，我们还可能识别出我们所知道的与免疫相关的特定过程，这些过程可能成为未来改进疫苗的目标。我们还将评估如果DC暴露在实验室中的病原体或疫苗中，是否可以检测到这些“签名”。这项工作旨在开发两个新的工具1。开放获取的参考数据，可以在未来的研究中利用来设计改进的疫苗配方，专门诱导明确的保护性信号2。基于实验室的筛选系统的概念验证，通过该系统，可以测试和合理选择候选疫苗。这些工具将为开发适用于广泛动物疾病的更有效的疫苗提供一种全新的方法，因此可能会产生深远的影响。它们将帮助开发更便宜、更高效的研究和开发方法，减少对动物模型的依赖。此外，这些工具与人类医学高度相关，在人类医学中，需要改进测试新疫苗的方法，但不可能进行传统的感染研究来测试疫苗。

Preventing and controlling infectious disease by vaccination is critical to the productivity and welfare of farmed animals worldwide, and necessary to maintain global food security. However, for many prevalent diseases, and in particular those for which immunity requires cell-mediated responses, effective deployable vaccines are not available and are proving extremely challenging to develop. Furthermore, the current approach for screening candidate vaccines involves inoculation of animals followed by disease challenge to test immunity. This is lengthy and costly, and frequently offers little insight into why a particular vaccine has failed. We aim to generate novel tools to address these problems by identifying features of the early immune response associated with initiating protective immune responses. Central to this process are specialised cells called dendritic cells (DCs). DCs reside in peripheral tissues (including skin) and, on encounter with a pathogen or vaccine, migrate via the lymphatic ducts to the lymph node. They carry with them both antigen and signals regarding the nature of the pathogen/vaccine, which together they use to initiate appropriate immune responses. The ability of the DCs to stimulate fully functional immune responses appears to be critically dependant on nature of the signals it received at the point of pathogen/vaccine encounter in the tissues. However the location of these processes makes them extremely difficult to access and study. We have established expertise in a model system (lymphatic cannulation) that allows us to collect large numbers of DCs from calves as they drain from the skin, following interactions with pathogens/vaccines. This provides a unique opportunity, not possible in other species, to investigate this pivotal early phase of the immune response in a natural setting. In this project we will collect DCs for laboratory analysis before, and immediately after, the administration of live pathogens selected on the basis that they stimulate predictable and well described immune responses. We will then use a range of techniques to investigate the response of the DCs to these pathogens, including recently developed sequencing tools that provide detailed resolution of the processes occurring, in which we have additional expertise. We will focus on defining responses to different categories of pathogen (a bacterium, parasite and virus) selected on the basis that they are expected to generate different responses in the DCs. We aim to define the processes that occur within DCs that enable them to induce immunity (as opposed to those processes which occur when immunity is not induced). This will provide us with 'signatures' that can be used as a basis for assessing vaccine-induced responses in future studies aiming to generate novel/improved vaccines. From these 'signatures' we may also be able to identify particular processes that we know are associated with immunity that could be targets for improved vaccines in the future. We will also assess whether these 'signatures' can be detected if DCs are exposed to pathogens or vaccines in the lab.This work aims to develop two novel tools1. Open-access reference data that could be exploited in future studies to design improved vaccine formulations that specifically induce defined protective signatures2. Proof-of-concept for a laboratory based screening system whereby candidate vaccines can be tested and rationally selected These tools will offer a totally novel approach to development of more efficacious vaccines applicable across a wide-range of animal diseases, and so could have far-reaching impact. They will aid the development of cheaper, more efficient research and development methods, with less reliance on animal models. Furthermore, such tools are highly relevant to human medicine where improved methods to test new vaccines are required but where traditional infection studies to test vaccines are not possible.