Anaplasma phagocytophilum induce Ixodes scapularis antifreeze glycoprotein gene e

描述（由申请人提供）：肩胛骨蜱在美国东北部和中西部北部越冬，并传播各种人类病原体，包括人类无形体病病原体嗜吞噬细胞无形体。我的初步数据表明，蜱虫体内嗜吞噬单胞虫的存在增加了肩胛骨单胞虫在寒冷中生存的能力。我已经确定了一种肩胛骨蜱抗冻糖蛋白，命名为IAFGP，并通过RNAi敲低研究证明了IAFGP对蜱在冰冻环境中生存的重要性。转染研究还表明，IAFGP增加了酵母细胞在低温下的活力。值得注意的是，我发现嗜吞噬细胞芽胞杆菌诱导iafgp的表达，从而提高了肩胛骨的耐寒性。这些数据确定了嗜吞噬菌与肩胛骨菌共生的分子基础。嗜吞噬芽胞杆菌诱导iafgp表达的机制尚不清楚。因此，将开展研究来阐明嗜吞噬芽孢杆菌影响载体基因表达的机制，以使其自身受益，并使其载体宿主在冰冻温度下存活。以下是了解其机制的具体目标：在目标1中，我将识别和表征肩胛肌中的iafgp启动子。本研究将探讨iafgp启动子是否在嗜吞噬细胞芽胞杆菌感染时被激活。在目标2中，将进行研究，以表征宿主转录激活因子可能参与iafgp启动子诱导的作用。综上所述，本研究不仅阐明了嗜吞噬单胞虫与肩胛骨单胞虫共生关系的分子机制，而且为研究宿主-病原体相互作用开辟了新的途径。

DESCRIPTION (provided by applicant): Ixodes scapularis ticks overwinter in the Northeast and Upper Midwest parts of United States, and transmit various human pathogens that include human anaplasmosis agent Anaplasma phagocytophilum. My preliminary data show that the presence of A. phagocytophilum in ticks increases the ability of I. scapularis to survive in the cold. I have identified an I. scapularis antifreeze glycoprotein, designated as IAFGP and demonstrate, via RNAi knockdown studies, the importance of IAFGP for the survival of ticks in a freezing environment. Transfection studies also show that IAFGP increases the viability of yeast cells subjected to low temperatures. Remarkably, I have found that A. phagocytophilum induce the expression of iafgp and thereby increase the cold tolerance of I. scapularis. These data define a molecular basis for symbiosis between A. phagocytophilum and I. scapularis. The mechanism by which A. phagocytophilum, induce iafgp expression is not understood. Therefore studies will be performed to elucidate the mechanism by which A. phagocytophilum influence vector gene expression for its own benefit as well as its vector host survival during freezing temperatures. Following are the specific aims that will be addressed to understand the mechanism: In aim 1, I will identify and characterize iafgp promoter in I. scapularis. The studies in this aim will address whether iafgp promoter is activated upon A. phagocytophilum infection. In aim 2, studies will be undertaken to characterize the role of host transcriptional activators that may be involved in iafgp promoter induction. Collectively, the proposed studies not only elucidate the molecular mechanisms of symbiotic association between A. phagocytophilum and I. scapularis ticks but also delineate a new approach to study host-pathogen interaction. PUBLIC HEALTH RELEVANCE: In United States, the life-cycle of Ixodes scapularis ticks that transmit several human pathogens involves overwintering stages. My previous studies show that a human pathogenic bacterium A. phagocytophilum establishes a symbiotic relationship with its arthropod vector to enhance survival in the cold, via the selective induction of a novel antifreeze glycoprotein (iafgp) in Ixodes scapularis. The goal of this proposal is to understand the mechanism by which A. phagocytophilum up-regulate iafgp gene expression for its own benefit and for its vector host survival in the cold temperature.