The Mechanism of Arenavirus Entry into Cells

致病性的新旧世界出血热病毒在人类中引起严重出血热。目前有 没有获得批准的疫苗或药物来对抗ARENA病毒感染。尽管进行了密集的研究，但禽流感病毒进入 无病毒糖蛋白(GP)介导的病毒-细胞融合进入宿主细胞的途径和机制尚不清楚 很好理解。东半球和新大陆地区的禽流感病毒使用不同的细胞受体，且特征不佳 进入和感染细胞的内吞途径。基于我们的初步数据和发表的工作，我们提出了一个 新旧世界新亚型禽流感病毒使用共同的后摄取途径进入 晚期内体的一个子集，含有特定的脂辅因子LBPA，但缺乏宿主限制因子IFITM3。 我们发现，LBPA促进了不同病毒的融合，而Lassa病毒绕过了 内体富含IFITM3，从而逃脱限制。我们还发现GP介导的融合需要 该糖蛋白中的硫醇-二硫键交换，并获得了GP介导病毒的证据 与酸性内小体融合前的膜通透性，我们假设这会促进随后的 病毒被揭开了。以下四个具体目标将检验上述假设。(一)划定进入路径 利用实时单一假病毒成像技术，对具有代表性的旧大陆和新大陆地区的禽流感病毒进行监测。(2)界定 LBPA在Arena病毒融合中的作用和确定GP脂相互作用基序。(3)审查对GP的要求 ARENAV融合中的硫醇-二硫键交换。(4)阐明GP介导的病毒膜的作用 脱膜过程中的渗透作用。成功完成拟议的实验将提供重要的 对Arena病毒进入/融合机制的基本见解并确定新的治疗靶点 干预。

Pathogenic Old and New World arenaviruses cause severe hemorrhagic fever in humans. There are currently no approved vaccines or drugs to battle arenavirus infection. Despite intensive studies, arenavirus entry pathways into host cells and the mechanism of arenavirus glycoprotein (GP) mediated virus-cell fusion are not well understood. Old World and New World arenaviruses use distinct cellular receptors and poorly characterized endocytic pathways to enter and infect cells. Based on our preliminary data and published work, we propose a novel overarching hypothesis that Old and New World arenaviruses use common post-uptake pathways to enter a subset of late endosomes that contain a specific lipid cofactor, LBPA, but lack the host restriction factor IFITM3. We found that fusion of diverse arenaviruses is promoted by LBPA and that the Lassa virus bypasses endosomes enriched in IFITM3, thereby escaping restriction. We also found that GP-mediated fusion requires thiol-disulfide interchange within this glycoprotein and obtained evidence that GP mediates arenavirus membrane permeabilization prior to fusion with acidic endosomes, which we hypothesized promotes subsequent virus uncoating. The following four Specific Aims will test the above hypotheses. (1) Delineate the entry pathways of representative Old and New World arenaviruses, using real-time single pseudovirus imaging. (2) Define the role of LBPA in arenavirus fusion and identify the GP lipid-interacting motif. (3) Examine the requirement for GP thiol-disulfide interchange in arenavirus fusion. (4) Elucidate a role of GP-mediated virus membrane permeabilization in uncoating. Successful completion of the proposed experiments will provide important fundamental insights into the mechanism of arenavirus entry/fusion and identify new therapeutic targets for intervention.