The role of TRIM2 and SIRPA in New World Arenavirus entry

新世界出血热沙粒病毒（NWA），如胡宁病毒，是啮齿动物传播的 当它们通过人畜共患病传染给人类时会导致约30%的死亡率。NWA的机制 诱导疾病仍然不确定，尽管它可能包括诱导高水平细胞因子 免疫系统的哨兵细胞感染，导致内皮细胞和血小板 功能障碍和神经系统疾病。Junín感染的幸存者产生强烈的体液免疫 免疫反应，这表明在感染后的早期控制感染对于 病毒清除虽然有效的胡宁病毒疫苗降低了发病率， 这种疾病以及其他已知的和新型的无疫苗的NWA的零星病例 或有效的治疗方法仍然存在。已经确定进化枝B致病性NWA结合 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 从酸性细胞室中分离出来的蛋白质并没有很好的确定。我们最近做了一个siRNA 用携带致病性Junín糖蛋白的假型病毒进行筛选，目的是发现 参与进入的宿主基因可以作为治疗靶点。我们发现TRIM2， 三重基序家族的成员，包括宿主固有的已知成员 针对病毒感染的防御，限制NWA内吞进入细胞。通过探测TRIM2 对于其他阻断NWA感染的宿主蛋白质的相互作用组，我们发现SIRPA，一种细胞， 抑制巨噬细胞吞噬肿瘤、死细胞和红细胞的表面蛋白， 也减少了感染。重要的是，SIRPA与TRIM2不同，抑制各种人类感染。 需要运输到酸性区室的致病性病毒，包括VSV，寨卡病毒， LCMV和埃博拉和SARS-Cov-2假病毒。我们的数据表明TRIM2和SIRPA作用于 在病毒进入/内化步骤。这些发现表明， 调节病毒的内吞作用和吞噬作用。 我们在此建议进一步研究病毒介导的内吞作用 和吞噬作用在体外，离体和体内的三个目标，将1）调查重叠， NWA进入和吞噬途径; 2）确定TRIM2/SIRPA抑制 利用TRIM2、SIRPA等相关基因敲除小鼠探讨其在感染中的作用 这些蛋白质在细胞类型特异性和体内感染的复制能力NWA。在 除了提供NWA进入细胞的机制见解外，这些研究还具有 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.