Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, United State of America.
Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas, United State of America.
PLoS Pathog. 2024 May 16;20(5):e1012010. doi: 10.1371/journal.ppat.1012010. eCollection 2024 May.
Arboviruses are a diverse group of insect-transmitted pathogens that pose global public health challenges. Identifying evolutionarily conserved host factors that combat arbovirus replication in disparate eukaryotic hosts is important as they may tip the balance between productive and abortive viral replication, and thus determine virus host range. Here, we exploit naturally abortive arbovirus infections that we identified in lepidopteran cells and use bacterial effector proteins to uncover host factors restricting arbovirus replication. Bacterial effectors are proteins secreted by pathogenic bacteria into eukaryotic hosts cells that can inhibit antimicrobial defenses. Since bacteria and viruses can encounter common host defenses, we hypothesized that some bacterial effectors may inhibit host factors that restrict arbovirus replication in lepidopteran cells. Thus, we used bacterial effectors as molecular tools to identify host factors that restrict four distinct arboviruses in lepidopteran cells. By screening 210 effectors encoded by seven different bacterial pathogens, we identify several effectors that individually rescue the replication of all four arboviruses. We show that these effectors encode diverse enzymatic activities that are required to break arbovirus restriction. We further characterize Shigella flexneri-encoded IpaH4 as an E3 ubiquitin ligase that directly ubiquitinates two evolutionarily conserved proteins, SHOC2 and PSMC1, promoting their degradation in insect and human cells. We show that depletion of either SHOC2 or PSMC1 in insect or human cells promotes arbovirus replication, indicating that these are ancient virus restriction factors conserved across invertebrate and vertebrate hosts. Collectively, our study reveals a novel pathogen-guided approach to identify conserved antimicrobial machinery, new effector functions, and conserved roles for SHOC2 and PSMC1 in virus restriction.
虫媒病毒是一组多样化的病原体，它们对全球公共卫生构成挑战。鉴定在不同真核宿主中对抗虫媒病毒复制的进化保守的宿主因子很重要，因为它们可能在病毒的有效和无效复制之间产生平衡，并因此决定病毒的宿主范围。在这里，我们利用我们在鳞翅目细胞中鉴定的天然无效虫媒病毒感染，并利用细菌效应蛋白来揭示限制虫媒病毒复制的宿主因子。细菌效应蛋白是由致病性细菌分泌到真核宿主细胞中的蛋白质，可以抑制抗菌防御。由于细菌和病毒可能会遇到共同的宿主防御，我们假设一些细菌效应蛋白可能会抑制限制鳞翅目细胞中虫媒病毒复制的宿主因子。因此，我们使用细菌效应蛋白作为分子工具来鉴定限制鳞翅目细胞中四种不同虫媒病毒的宿主因子。通过筛选来自七种不同细菌病原体的 210 种效应蛋白，我们鉴定出几种单独拯救这四种虫媒病毒复制的效应蛋白。我们表明，这些效应蛋白编码不同的酶活性，这些活性是打破虫媒病毒限制所必需的。我们进一步将福氏志贺菌编码的 IpaH4 表征为一种 E3 泛素连接酶，它直接泛素化两种进化上保守的蛋白质 SHOC2 和 PSMC1，促进它们在昆虫和人类细胞中的降解。我们表明，昆虫或人类细胞中 SHOC2 或 PSMC1 的耗尽都促进了虫媒病毒的复制，表明这些是跨无脊椎动物和脊椎动物宿主保守的古老病毒限制因子。总的来说，我们的研究揭示了一种新的病原体引导方法，用于鉴定保守的抗菌机制、新的效应蛋白功能以及 SHOC2 和 PSMC1 在病毒限制中的保守作用。
