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

森林斑疹伤寒是一种由东方体引起的危及生命的疾病，是一种内毒素阴性细菌， 在内皮细胞和单核细胞中优先复制。大约有一百万人被感染 每年；世界上约三分之一的人口面临感染的风险。目前还没有有效的疫苗来治疗这种疾病。 感染；关于疾病发病机制和T细胞免疫的信息有限。要应对这些挑战， 在这一研究领域，我们开发了能够模拟人类病理特征的C57BL6小鼠模型 丛林斑疹伤寒。我们发现致命性感染与偏向1型的免疫反应有关，这种免疫反应与 多个器官细胞过度凋亡和血管损伤。此外，我们还确定了 顶级候选疫苗(P47和P56)及其保护性片段来自对一组 东方体主要抗原/配方在近交系小鼠中对抗同系物和异源挑战。目标是 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 感染卡氏钩端螺旋体，这是人类感染最流行的菌株。我们的中心假设 通过多变种疫苗或非致命性感染进行适当的T细胞启动，将有助于诱导 平衡免疫力，抵抗细菌传播、急性组织损伤和严重的丛林斑疹伤寒。目标一号将测试 多变型DNA疫苗平台可通过刺激B6小鼠抵御严重斑疹伤寒 平衡激活T细胞和B细胞免疫。在免疫和致命挑战的不同阶段，我们 将评估组织的细菌负荷、病理变化以及宿主免疫的动力学和水平 回应。目标2将检验T细胞，特别是抗原特异性CD8+T细胞的进行性丧失， 是内皮损伤的潜在机制，也是致死性感染的致死因素。我们将使用 代表四个预测T表位的合成肽和用于估计细胞因子的重组蛋白 重呼试验中的产量，以及分泌细胞因子的T细胞的频率和命运。试管数据将会是 结合免疫组织化学染色检测脾等脏器中的凋亡细胞。这种疫苗- 基于T细胞的研究认可了研究团队(每个团队都有独特的专业知识)之间的协同；它利用 UTMB最先进的ABSL3/BSL3设施。这项研究的长期目标是检查 控制斑疹伤寒的多变DNA疫苗平台和保护性细胞免疫。 免疫保护宿主中平衡的T细胞激活的经验证据将是特别重要的 重要的是，考虑到这一被忽视的新疾病的现状和差距。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.