Host factors required for Leishmania infection

描述（由申请人提供）：利什曼病是一种被忽视的热带疾病，由白蛉传播，由利什曼原虫属的原生动物寄生虫引起，影响全球1200万人。已经开发了用于研究宿主-利什曼原虫相互作用的果蝇模型，并且建议利用该模型系统中可用的独特且强大的遗传工具来发现利什曼原虫寄生虫的吞噬作用和/或细胞内存活所需的新颖且保守的因子。事实上，CD 36样清道夫受体已被确定为果蝇抗寄生虫防御的关键组成部分。将这一发现扩展到小鼠，发现CD 36缺陷导致利什曼原虫感染后扩大和持续的足垫病变，并且离体CD 36缺陷型巨噬细胞呈现显著减少的寄生虫空泡。这些表型表明CD 36清道夫受体在L. amazonensis感染，其将在目的1中进一步表征。使用果蝇细胞为基础的模型，全基因组RNAi筛选，以确定参与亚马逊乳杆菌无鞭毛体的吞噬作用的基因。该筛选鉴定了利什曼原虫吞噬作用所需的52个高度保守的基因，但不参与细菌的吞噬作用。一个候选者是跨膜蛋白德雷珀，一种清道夫受体，以其在识别和清除凋亡或受损细胞中的作用而闻名，这表明它也在寄生虫识别中起作用（目的2）。目前尚不清楚， 其它候选物涉及寄生物识别、细胞内运输或寄生物吞噬/侵入的其它方面。为了集中在最有前途的候选人在哺乳动物中的研究，目标3将这些其他因素的功能，在哺乳动物巨噬细胞系中的利什曼原虫的吞噬作用。

DESCRIPTION (provided by applicant): Leishmaniasis is a neglected tropical disease, vectored by sand flies and caused by the protozoan parasites of the Leishmania genus, that affects 12 million people globally. Drosophila models for the study of host-Leishmania interactions have been developed, and it is proposed to exploit the unique and powerful genetic tools available in this model system to discover novel and conserved factors required for the phagocytosis and/or intracellular survival of Leishmania parasites. In fact, CD36-like scavenger receptors have been identified as critical components of anti-parasitic defenses in Drosophila. Extending this discovery to mice, CD36 deficiency was found to cause enlarged and persistent foot pad lesions following Leishmania infection, and ex vivo CD36-deficient macrophages present markedly reduced parasitophorous vacuoles. These phenotypes demonstrate that the CD36 scavenger receptor plays a crucial role in L. amazonensis infection, which will be further characterized in Aim 1. Using a Drosophila cellbased model, a genome-wide RNAi screen to identify genes involved in the phagocytosis of L.amazonensis amastigotes was also performed. This screen identified 52 highly conserved genes required for the phagocytosis of Leishmania, but not involved in phagocytosis of bacteria. One candidate is the transmembrane protein Draper, a scavenger receptor best known for its role in recognizing and clearing apoptotic or damaged cells, suggesting it also functions in parasite recognition (Aim 2). It is not yet known if the other candidates are involved in parasite recognition, intracellular trafficking or other aspecs of parasite phagocytosis/invasion. In order to focus on the most promising candidates for study in mammals, Aim 3 will characterize the function of these other factors in the phagocytosis of Leishmania in mammalian macrophage cell lines.