The Mechanism of Arenavirus Entry into Cells

致病性旧大陆和新大陆沙粒病毒在人类中引起严重的出血热。目前有 没有批准的疫苗或药物来对抗沙粒病毒感染。尽管进行了深入的研究， 进入宿主细胞的途径和沙粒病毒糖蛋白（GP）介导的病毒-细胞融合机制， 很好理解。旧大陆和新大陆沙粒病毒使用不同的细胞受体， 通过内吞途径进入并感染细胞。根据我们的初步数据和已发表的工作，我们提出了一个 一种新的总体假设，即旧世界和新世界沙粒病毒使用共同的摄取后途径进入 晚期核内体的一个子集，含有特定的脂质辅因子LBPA，但缺乏宿主限制因子IFITM 3。 我们发现LBPA促进了不同沙粒病毒的融合，而拉沙病毒绕过了LBPA， 内体富含IFITM 3，从而逃避限制。我们还发现GP介导的融合需要 该糖蛋白内的巯基-二硫键交换，并获得了GP介导沙粒病毒的证据 在与酸性内体融合之前，膜透化，我们假设这促进了随后的 病毒脱壳以下四个具体目标将检验上述假设。(1)画出进入通道 代表性的旧世界和新世界沙粒病毒，使用实时单假病毒成像。(2)定义 LBPA在沙粒病毒融合中的作用，并鉴定GP脂质相互作用基序。(3)检查GP的要求 沙粒病毒融合中的巯基-二硫键交换。(4)阐明GP介导的病毒膜的作用 脱膜中的透化。成功完成拟议的实验将提供重要的 沙粒病毒进入/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.