T-Cell Quality and Protective Immunity in a Murine Scrub Typhus Model

恙虫病是一种由恙虫病东方体引起的危及生命的疾病， 优先在内皮细胞和单核细胞中复制。大约有一百万人被感染 每年约有三分之一的世界人口面临感染风险。目前还没有有效的疫苗 感染;关于疾病发病机制和T细胞免疫的信息有限。为了应对这些挑战， 在这一研究领域，我们已经开发了C57 BL 6小鼠模型，可以模拟人类的病理特征， 丛林斑疹伤寒我们发现致死性感染与偏向1型的免疫反应有关， 伴有多器官细胞凋亡和血管损伤。此外，我们还确定了 最佳候选疫苗（p47和p56）及其保护性片段，来自对一组 东方主要抗原/配方对同源物和异源的挑战远交小鼠。目标 这项研究的目的是研究T细胞反应如何控制保护性和致病性免疫反应， 感染O.恙虫病Karp是人类感染最普遍的毒株。我们的核心假设 通过多变异疫苗或非致死性感染，适当的T细胞引发将有助于引发 对细菌传播、急性组织损伤和严重恙虫病的平衡免疫力。目标1将测试这一点 多变异DNA疫苗平台可以通过刺激B6小鼠抵抗严重的恙虫病， T细胞和B细胞免疫的平衡激活。在免疫和致命攻击的不同阶段，我们 将评估组织细菌负荷，病理变化，以及宿主免疫的动力学和水平， 应答目的2将检验T细胞，特别是Ag特异性CD 8 + T细胞的进行性损失， 是内皮损伤的潜在机制和致死性感染的促成因素。我们将使用 代表四个预测T表位的合成肽和重组蛋白以评估细胞因子 再调用测定中的生产，以及分泌精氨酸的T细胞的频率和命运。体外数据将 与来自脾和其它器官中凋亡细胞的免疫染色的那些整合。这种疫苗- 基于T细胞的研究支持研究团队之间的协同作用（每个团队都有独特的专业知识）;它利用 UTMB最先进的ABSL 3/BSL 3设施。这项研究的长期目标是研究 多变异DNA疫苗平台和保护性细胞免疫用于控制恙虫病。 在免疫保护的宿主中平衡的T细胞活化的经验证据将是特别重要的。 鉴于这一被忽视的新出现疾病的现状和差距，这一点非常重要。这项及时的研究将有一个 对其他细胞内病原体的广泛影响。

Scrub typhus is a life-threatening disease caused Orientia tsutsugamushi, a LPS-negative bacterium that replicates preferentially in endothelial cells and monocytes. Approximately one million people are infected every year; about one third of the world's population is at risk of infection. There is no effective vaccine for this infection; information on disease pathogenesis and T cell immunity is limited. To address these challenges in this research field, we have developed C57BL6 mouse models that can mimic pathological features of human scrub typhus. We found that lethal infection was linked to type 1-biased immune responses, which correlated with excessive cellular apoptosis and vascular damage in multiple organs. In addition, we have identified the top vaccine candidates (p47 and p56) and their protective fragments from extensive studies of a panel of Orientia major antigens/formulas against homologues and heterologous challenges in outbred mice. The goal of this study is to examine how T cell responses control protective and pathogenic immune responses during infection with O. tsutsugamushi Karp, the most prevalent strain for human infections. Our central hypothesis is that appropriate T cell priming, through multi-variant vaccines or non-lethal infection, will help elicit a balanced immunity against bacterial spread, acute tissue damage and severe scrub typhus. Aim 1 will test that a multi-variant DNA vaccine platform can protect B6 mice against severe scrub typhus through the stimulation of a balanced activation of T- and B-cell immunity. At different stages of immunization and lethal challenge, we will evaluate tissue bacterial loads, pathological changes, as well as the kinetics and levels of host immune responses. Aim 2 will test the hypothesis that a progressive loss of T cells, especially Ag-specific CD8+ T cells, is the underlying mechanism for endothelial damage and contributing factor for lethal infection. We will use synthetic peptides that represent four predicted T epitopes and recombinant proteins to estimate cytokine production in re-call assays, as well as the frequency and fate of cytokine-secreting T cells. In vitro data will be integrated with those from immunostaining of apoptotic cells in the spleen and other organs. This vaccine- based, T cell-focused study endorses synergy among research teams (each with unique expertise); it utilizes the state-of-art ABSL3/BSL3 facilities at UTMB. The long-term goal of this study is to examine the potential of a multi-variant DNA vaccine platform and protective cellular immunity for the control of scrub typhus. Experiential evidence for a balanced T-cell activation in an immune-protected host would be particularly important, given the current status and gap in this neglected emerging disease. This timely study will have a broad implication for other intracellular pathogens.