Babesiosis: An Emerging Infectious Threat to Transfusion Medicine

描述（由申请人提供）：巴贝斯虫病是一种人畜共患病，一种由动物传染给人的疾病。啮齿动物寄生虫微巴贝斯虫和牛病原体巴贝斯虫是迄今为止全球报告的大多数人类感染的原因。从血液安全的角度来看，涉及巴贝斯虫的输血传播感染在美国变得越来越成问题，每年报告的数量逐渐增加。因此，对这种血源性寄生虫的研究应作为输血医学的重点。我们的目的是了解B. divergens入侵人体红细胞（RBC）的过程，最终目的是开发在入侵中发挥关键作用的寄生虫分子作为诊断和血液筛查工具。我们用于研究分化芽胞杆菌入侵人类红细胞的体外系统，允许直接探索与寄生虫入侵人类红细胞相关的事件，使用分化芽胞杆菌的活的分殖子。寄生物表面的分子和顶端细胞器分泌的分子在寄主/寄主界面起作用，如果我们要明确入侵机制的步骤和寻找新的治疗靶点，就需要对它们进行识别，确定它们的相互作用和功能。我们已经确定了一种假定的红细胞结合配体Bd30，我们项目的重点是研究它在寄生虫入侵期间与红细胞，特别是糖蛋白的相互作用。本研究有三个具体目的：(1)鉴定嗜糖蛋白A （GPA）和嗜糖蛋白B （GPB）是嗜糖蛋白A （GPA）和/或嗜糖蛋白B （GPB）的红细胞受体；(2)验证Bd30是嗜糖蛋白A （GPA）和/或嗜糖蛋白B （GPB）结合的配体；(3)评价嗜糖蛋白A和/或嗜糖蛋白B与Bd17相互作用在嗜糖酵母入侵中的功能意义。提出的方法包括使用RBC的特定酶处理抑制入侵试验，缺乏定义的RBC抗原的突变细胞和使用抗体和竞争肽；使用天然和重组Bd30配体蛋白进行红细胞结合试验，在入侵试验中使用抗Bd30的抗体，并提出基因删除以研究其功能。因此，该项目的主要目标是阐明发散芽孢杆菌分裂子进入红细胞的分子机制。预计本提案中详细的研究将产生用于诊断、流行病学以及治疗和预防人类巴贝斯虫病的试剂，并协助开发筛选血液制品的产品。

DESCRIPTION (provided by applicant): Babesiosis is a zoonosis, a disease communicable from animals to man. The rodent parasite, Babesia microti and the bovine pathogen, Babesia divergens are responsible for most of the human infections that have been reported to date, globally. From a blood safety perspective, transfusion-transmitted infections involving Babesia spp. have become increasingly problematic in the USA, with progressively more reported each year. Therefore the study of this blood-borne parasite should be considered as a priority for transfusion medicine. Our purpose is to understand the invasion process of B. divergens into the human red blood cell (RBC), with the ultimate aim of exploiting parasite molecules found to play key roles in invasion as diagnostic and blood screening tools. The in-vitro system that we use for studying invasion of the human red cell by B. divergens, permits direct exploration of the events associated with parasite invasion of the human RBC, using viable merozoites of B. divergens. Molecules on the surface of the parasite and those secreted by apical organelles function at the host/parasite interface, and we need to identify them and determine their interactions and function, if we are to define the steps in the invasion mechanism and identify new therapeutic targets. We have identified one such putative RBC binding ligand, Bd30 and the focus of our project is the study of its interaction with the RBC, specifically the glycophorins, during parasite invasion. There are three specific aims in this proposal (1) To characterize glycophorin A (GPA) and glycophorin B (GPB) as RBC receptors for B. divergens invasion (2) To validate Bd30 as the B. divergens ligand that binds glycophorin A (GPA) and/or glycophorin B (GPB) and to characterize Bd30 in the parasite and (3) To evaluate the functional significance of the interaction between GPA and/or GPB and Bd17 in merozoite invasion. Methodology that is proposed includes inhibition of invasion assays using specific enzyme treatments of the RBC, mutant cells lacking defined RBC antigens and the use of antibodies and competitor peptides; erythrocyte binding assays using native and recombinant Bd30 ligand protein and antibodies against Bd30 in invasion assays, as well as proposed gene deletion to study its function. Thus, the major goal of the project is to elucidate the molecular mechanisms involved in the entry of B. divergens merozoites into the erythrocyte. It is anticipated that studies detailed in this proposal will result in reagents for diagnosis, epidemiology and treatment and prevention of human babesiosis, and assist in developing products to screen blood products.