The role of TRIM2 and SIRPA in New World Arenavirus entry

新世界出血热阿雷纳病毒，如Junín病毒，是由啮齿动物传播的 当病毒传播到人类体内时会导致约30%的死亡率。美国国家科学院的机制 诱发疾病仍然不确定，尽管它可能包括诱导高水平的细胞因子 受感染的免疫系统哨兵细胞，导致内皮细胞和血栓形成 功能障碍和神经系统疾病。Junín感染的幸存者表现出强烈的体液 免疫反应，这表明在感染后早期控制感染对 清除病毒。尽管一种有效的Junín病毒疫苗降低了发病率， 这种疾病的零星病例以及其他尚无疫苗的已知和新的非霍奇金淋巴瘤 否则有效的治疗方法仍然会出现。已经确定的是，B分支致病的NWAs与 转铁蛋白受体1和细胞表面的其他受体，但导致它们进入的步骤 不能很好地确定来自酸性细胞室的物质。我们最近进行了一次siRNA 筛选携带致病Junín糖蛋白的伪型病毒，目的是找到 宿主基因参与了可能作为治疗靶点的进入。我们发现TRIM2，a 三方主题家族的成员，包括主持人固有的众所周知的成员 对病毒感染的防御，限制了NWA内吞进入细胞。通过探测TRIM2 与其他阻止NWA感染的宿主蛋白相互作用时，我们发现Sirpa细胞 抑制巨噬细胞吞噬肿瘤、死亡细胞和红细胞的表面蛋白， 还可以减少感染。重要的是，Sirpa与TRIM2不同，它抑制各种人类感染 需要运输到酸性隔间的致病病毒，包括VSV、寨卡病毒、 LCMV和埃博拉病毒以及SARS-CoV-2伪病毒。我们的数据表明TRIM2和Sirpa起作用 在病毒进入/内化阶段。这些发现表明，存在着共同的机制 来调节病毒的吞噬和吞噬作用。 我们建议进一步研究病毒介导的内吞作用之间的重叠。 以及体外、体外和体内的吞噬作用，这三个目标将1)研究 NWA进入和吞噬途径；2)确定TRIM2/Sirpa抑制 3)利用TRIM2、Sirpa和其他相关的基因敲除小鼠来检测它们的作用 这些蛋白质在细胞类型特异性和体内感染复制能力强的NWAs。在……里面 这些研究除了提供对NWAs进入细胞的机制的洞察外，还有 增加我们对宿主因素如何限制感染并可能导致 治疗干预的新方法。

New world hemorrhagic fever arenaviruses (NWAs), such as Junín virus, are rodent-transmitted viruses that cause ~30% mortality when they zoonose into humans. The mechanism by the NWAs induce disease is still not certain, although it likely includes induction of high levels of cytokines by infected sentinel cells of the immune system, leading to endothelia and thrombocyte dysfunction and neurological disease. Survivors of Junín infection develop strong humoral immune responses, suggesting that controlling infection at early times post-infection is critical for virus clearance. Although an effective Junín virus vaccine has decreased disease incidence, sporadic cases of this as well as the other known and novel NWAs for which there are no vaccines or effective therapeutics still occur. It is well-established that the clade B pathogenic NWAs bind to transferrin receptor 1 and other receptors on the cell surface, but the steps leading to their entry from an acidic cellular compartment are not well-determined. We recently performed a siRNA screen with pseudotyped viruses bearing a pathogenic Junín glycoprotein with the goal of finding host genes involved in entry that could serve as therapeutic targets. We found that TRIM2, a member of the tripartite motif family that includes well-known members of the host's intrinsic defense against viral infections, limits NWA endocytosis into cells. By probing the TRIM2 interactome for other host proteins that block NWA infection, we discovered that SIRPA, a cell surface protein that inhibits macrophage phagocytosis of tumor and dead cells and erythrocytes, also decreases infection. Importantly, SIRPA, unlike TRIM2, inhibits infection by various human pathogenic viruses that require trafficking to an acidic compartment, including VSV, Zika virus, LCMV and Ebola and SARS-Cov-2 pseudoviruses. Our data suggest that TRIM2 and SIRPA act at the viral entry/internalization step. These finding suggests that there are common mechanisms that regulate virus endocytosis and phagocytosis. We propose here to further investigate the overlap between virus-mediated endocytosis and phagocytosis in vitro, ex vivo and in vivo in three aims that will 1) investigate the overlap in the NWA entry and phagocytosis pathways; 2) determine where TRIM2/SIRPA inhibition of infection occurs; and 3) use TRIM2, SIRPA and other relevant knockout mice to probe the roles of these proteins in cell-type specific and in vivo infection by replication-competent NWAs. In addition to providing mechanistic insight into the entry of NWAs into cells, these studies have the potential of increasing our understanding as to how host factors limit infection and could lead to new approaches to therapeutic intervention.