Rickettsial infection of humanized mice

我们的长期目标是阐明复杂的免疫和病理机制的人类在 对病原体（如立克次体）的反应，其发病机制涉及血管内衬细胞 （内皮细胞）。这些节肢动物携带的专性细胞内细菌包括Rocky的病原体 山地斑点热（立克次体）和流行性斑疹伤寒（R。prowazekii）。他们是世界上 人类已知的致命病原体（未经治疗的病例病死率为20-30%），它们被指定为 选择可能用于生物恐怖主义的物质人类的相关数据落后于那些 主要是由于很难正确识别立克次体病病例。这 知识上的差距阻碍了新的干预目标的发现。我们的目标是发展一个 流行性斑疹伤寒的人源化小鼠模型作为其他感染性疾病的范例， 细胞参与发病机制。假设是人源化小鼠产生立克次体引发的 血管病变和针对立克次体的适应性免疫应答。具体目标是：1）确定 在人源化小鼠中浸润立克次体感染的人血管床的人白细胞的类型;和2） 以测量人源化小鼠中人B细胞和T细胞介导的抗立克次体免疫应答。的 实验方法是：a）鉴定感染了R. prowazekii或R.立克次体和人造人血管床中立克次体负荷的测量;和B） 抗立克次体抗体的人免疫球蛋白亚型和抗原特异性人T 感染立克次体的人源化小鼠中的细胞增殖、细胞因子产生和细胞毒性。的 人源化小鼠将允许：i）鉴定治疗性干预和保护性干预的靶点， 用于疫苗开发的人类识别的抗原; ii）研究 人白细胞和立克次体感染的内皮细胞; iii）确定 血管渗漏，这些疾病的发病机制的中心特征; iv）自然和 疫苗诱导的免疫应答;和v）测试候选疫苗的免疫原性和保护。

Our long-term goal is to elucidate the complex immunological and pathological mechanisms of humans in response to agents, such as Rickettsia, whose pathogenesis involves the cells lining the vasculature (endothelial cells). These arthropod-borne obligately intracellular bacteria include the agents of Rocky Mountain spotted fever (Rickettsia rickettsii) and epidemic typhus (R. prowazekii). They are among the most lethal pathogens known to man (case fatality rate of 20-30% in untreated cases), and they are designated select agents with potential use for bioterrorism. Relevant data from humans have lagged behind those derived from the animal models due mainly to the difficulty in correctly identifying cases of rickettsioses. This gap in knowledge has prevented the discovery of novel targets of intervention. Our objective is to develop a humanized mouse model of epidemic typhus as a paradigm for other infectious diseases in which endothelial cells are involved in the pathogenesis. The hypothesis is that humanized mice develop rickettsia- triggered vascular lesions and adaptive immune responses against rickettsiae. The specific aims are: 1) to identify the types of human leukocytes that infiltrate rickettsia-infected human vascular beds in humanized mice; and 2) to measure the human B-cell and T cell-mediated anti-rickettsial immune responses in humanized mice. The experimental approaches are: a) identification of infiltrating leukocytes in humanized mice infected with R. prowazekii or R. rickettsii and measurement of rickettsial loads in synthetic human vascular beds; and b) determination of human immunoglobulin subtypes of anti-rickettsiae antibodies and antigen-specific human T cell proliferation, cytokine production, and cytotoxicity in humanized mice infected with rickettsiae. The humanized mice will allow: i) the identification of targets of therapeutic intervention and of protective antigens recognized by humans for vaccine development; ii) the study of the in vivo interactions between human leukocytes and rickettsia-infected endothelial cells; iii) the determination of the mechanism(s) of vascular leakage, a central feature of the pathogenesis of these diseases; iv) the evaluation of natural and vaccine-induced immune responses; and v) testing of immunogenicity and protection of candidate vaccines.