Defining mechani1sms of CD8+ T-cell mediated immunity - using an integrated longitudinal model to achieve an elusive goal.

疫苗是实施的最成功和最具成本效益的卫生干预战略之一，在减少许多人类和动物疾病的发病率方面发挥了关键作用。然而，对于CD 8 + T细胞介导的免疫被认为对免疫有实质性贡献的许多疾病（例如HIV、疟疾、非洲猪瘟），目前没有可获得的引发保护性CD 8 + T细胞应答的疫苗。病毒载体疫苗是最有希望的传递系统，特别是在模式物种中。然而，在目标人类或动物物种中，这些疫苗尽管通常具有高度免疫原性（诱导T细胞应答），但仅显示出有限的产生保护性CD 8 + T细胞的能力。免疫原性和保护之间的差异表明，疫苗诱导的T细胞应答的定性而非定量参数是有缺陷的。到目前为止，我们对这些参数的理解是有限的，这种“知识差距”阻碍了设计新颖有效的疫苗递送平台的完全合理的方法。小泰勒虫是一种蜱传的原生动物寄生虫，在撒哈拉以南非洲的畜牧业中造成约6亿美元/年的重大经济损失。这一损失主要由小农户承担，对低/中等收入国家的一些最弱势群体来说可能是毁灭性的。对T. parva与CD 8 + T细胞应答相关，这可以在实验条件下使用“感染和治疗方法”（ITM）或自体T细胞来模拟。细小病毒感染的细胞系（ACL）免疫，其已用于研究和预防保护性免疫。T. parva的研究一直在开发一种亚单位疫苗，可以作为可持续T。小行星防治方案。使用多种病毒载体（金丝雀痘、Ad、MVA）递送已知T. parva CD 8 + T细胞抗原已证明具有免疫原性，但对体内攻击的保护作用有限。最近的数据表明，Ad/MVA诱导的CD 4 + T细胞应答的缺陷导致CD 8 + T细胞功能缺陷，新型病毒载体的开发和试验需要大量的时间和资源投入，并且受到合适候选物的可用性的限制。虽然令人失望，目前的病毒载体，以诱导保护性CD 8 + T细胞反应的失败，可以利用来了解如何诱导T细胞反应不同于等效的，但保护性的T细胞responses.In这个项目中，我们建议使用T细胞的“纵向”模型。parva免疫接种，其中在顺序施用非保护性（Ad/MVA）和保护性（ITM）免疫接种后集中分析个体的T细胞应答，以使得能够分析影响表型转变的参数，从而定义确定CD 8 + T细胞的保护效力的免疫学参数。通过促进动物内比较，该模型具有许多优于传统队列研究的优点。该项目的目标是确定：1。Ad/MVA异源初免-加强免疫诱导的非保护性CD 8 + T细胞的功能和转录组与保护性T细胞有何不同？特异性CD 8 + T细胞？2. Ad/MVA异源初免-加强免疫诱导的CD 4 + T细胞的功能和转录组与T细胞保护相关的功能和转录组有何不同？parva感染？3. CD 8 + T细胞的功能能力如何依赖于CD 4 + T细胞？这些信息将提供数据来理解决定CD 8 + T细胞疫苗成功或失败的基本免疫学机制，并可用于为T细胞疫苗载体的改进设计/工程化提供信息。细小病毒和其他人类和兽医病原体。

Vaccines have been amongst the most successful and cost-effective health intervention strategies implemented and have played a critical role in reducing the incidence of many human and animal diseases. However, for a number of diseases (e.g. HIV, malaria, African Swine Fever) for which CD8+ T-cell mediated immunity is thought to make a substantial contribution to immunity, there are currently no available vaccines that elicit protective CD8+ T-cell responses. Viral-vectored vaccines are the delivery system that has shown most promise, especially in model species. However, in target human or animal species these vaccines, although usually highly immunogenic (induce T-cell responses), have demonstrated only a limited ability to generate protective CD8+ T-cells. The discrepancy between immunogenicity and protection indicates that qualitative, rather than quantitative, parameters of the vaccine-induced T-cell responses are deficient. As yet our understanding of what these parameters are is limited and this 'knowledge-gap' prevents a fully rational approach to design of novel, efficacious vaccine delivery platforms. Theileria parva, a tick-borne protozoan parasite of cattle, causes major economic losses in livestock farming in sub-Saharan Africa of ~$600M/yr. This loss is largely borne by small-holder farmers and can be devastating for some of the most vulnerable people in low/middle income countries. Natural immunity to T. parva is associated with CD8+ T-cell responses, which can be mimicked under experimental conditions using either an 'infection-and-treatment method' (ITM) or autologous T. parva-infected cell line (ACL) immunisation which have been used to study and characterise protective immunity. A major aim of T. parva research has been the development of a subunit vaccine that could be deployed as part of sustainable T. parva control programme. Trials using a variety of viral vectors (canarypox, Ad, MVA) to deliver known T. parva CD8+ T-cell antigens have demonstrated immunogenicity but only limited protection from in vivo challenge. Recent data has implicated defects in Ad/MVA-induced CD4+ T-cell responses as contributing to deficient CD8+ T-cell functionality.Development and trialling of novel viral vectors requires substantial investments of time and resources and is limited by the availability of suitable candidates. Although disappointing, failure of current viral vectors to induce protective CD8+ T-cell responses can be exploited to understand how the induced T-cell responses differ from equivalent but protective T-cell responses.In this project we propose to use a 'longitudinal' model of T. parva immunisation in which the T-cell responses of individuals are intensively analysed following sequential administration of a non-protective (Ad/MVA) and protective (ITM) immunisation to enable the parameters that influence the transition of phenotypes to be analysed and so define the immunological parameters that determine protective efficacy of CD8+ T-cells. By facilitating intra-animal comparisons this model has a number of advantages over conventional cohort studies. The objectives of the project are to define: 1. How does the function and transcriptome of non-protective CD8+ T-cells induced by Ad/MVA heterologous prime-boost differ from protective T. parva-specific CD8+ T-cells? 2. How does the function and transcriptome of CD4+ T-cells induced by Ad/MVA heterologous prime-boost differ from those associated with protection from T. parva infection? 3. How dependent on CD4+ T-cells is the functional competency of CD8+ T-cells? This information will provide the data to understand the fundamental immunological mechanisms that dictate CD8+ T-cell vaccine success or failure and can be used to inform the design/engineering of improved novel vaccine vectors for T. parva and other human and veterinary pathogens.