TIM-1 Mediates Dystroglycan-Independent Entry of Lassa Virus
TIM-1 Mediates Dystroglycan-Independent Entry of Lassa Virus
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DOI：
10.1128/jvi.00093-18
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发表时间：
2018-08-01
影响因子：
5.4
通讯作者：
Maury, Wendy
中科院分区：
文献类型：
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作者：
Brouillette, Rachel B.;Phillips, Elisabeth K.;Maury, Wendy
拉沙病毒（LASV）是一种旧大陆沙粒病毒，每年在西非造成数十万人感染。LASV进入多种细胞类型是通过与普遍存在的受体α-肌营养不良蛋白聚糖（α DG）上存在的糖基转移酶LARGE修饰的O-连接聚糖相互作用介导的。然而，缺乏α DG的细胞允许LASV感染，表明存在替代受体。先前的研究表明，磷脂酰丝氨酸（PtdSer）结合受体Axl和Tyro 3沿着C型凝集素受体介导α DG非依赖性进入。在这里，我们证明了另一种PtdSer受体TIM-1介导LASV糖蛋白（GP）假型病毒粒子进入α DG敲除的HEK 293 T和野生型（WT）Vero细胞，这些细胞表达缺乏适当糖基化的α DG。为了研究TIM-1介导增强进入的机制，我们证明了TIM-1 IgV结构域PtdSer结合口袋的诱变废除了转导。此外，人TIM-1 IgV结构域结合单克隆抗体ARD 5以剂量依赖性方式阻断携带LASV GP的假病毒体的转导。最后，正如我们之前对使用TIM-1进入的其他病毒所显示的那样，嵌合TIM-1蛋白质取代了来自小鼠白血病病毒包膜（Env）的富含脯氨酸的区域（PRR）作为一种感受态受体。这些研究提供的证据表明，在没有功能性α DG的情况下，TIM-1通过病毒粒子与TIM-1的IgV PtdSer结合口袋的相互作用介导LASV假病毒颗粒的进入。重要PtdSer受体，如TIM-1，正在成为许多包膜病毒的关键进入因子。最近，丙型肝炎病毒和寨卡病毒已被添加到越来越多的名单中。PtdSer受体通过嵌入病毒包膜中的PtdSer的结合与包膜病毒接合，将其定义为GP非依赖性受体。这种GP非依赖性进入机制应该有效地介导所有包膜病毒的进入，但先前发现LASV GP假型病毒对HEK 293 T细胞中的PtdSer受体增强无反应。在这里，我们证明，LASV假病毒体可以利用PtdSer受体TIM-1，但只有在适当的糖基化α-肌营养不良蛋白聚糖（α DG），LASV的高亲和力细胞表面受体的情况下。我们的研究揭示了LASV受体的利用，并解释了为什么以前的研究与α-DG表达细胞没有发现，LASV假病毒粒子利用PtdSer受体的病毒摄取。
Lassa virus (LASV) is an Old World arenavirus responsible for hundreds of thousands of infections in West Africa every year. LASV entry into a variety of cell types is mediated by interactions with glycosyltransferase LARGE-modified O-linked glycans present on the ubiquitous receptor alpha-dystroglycan (alpha DG). However, cells lacking alpha DG are permissive to LASV infection, suggesting that alternative receptors exist. Previous studies demonstrated that the phosphatidylserine (PtdSer)-binding receptors Axl and Tyro3 along with C-type lectin receptors mediate alpha DG-independent entry. Here, we demonstrate that another PtdSer receptor, TIM-1, mediates LASV glycoprotein (GP)pseudotyped virion entry into alpha DG-knocked-out HEK 293T and wild-type (WT) Vero cells, which express alpha DG lacking appropriate glycosylation. To investigate the mechanism by which TIM-1 mediates enhancement of entry, we demonstrate that mutagenesis of the TIM-1 IgV domain PtdSer-binding pocket abrogated transduction. Furthermore, the human TIM-1 IgV domain-binding monoclonal antibody ARD5 blocked transduction of pseudovirions bearing LASV GP in a dose-dependent manner. Finally, as we showed previously for other viruses that use TIM-1 for entry, a chimeric TIM-1 protein that substitutes the proline-rich region (PRR) from murine leukemia virus envelope (Env) for the mucin-like domain served as a competent receptor. These studies provide evidence that, in the absence of a functional alpha DG, TIM-1 mediates the entry of LASV pseudoviral particles through interactions of virions with the IgV PtdSer-binding pocket of TIM-1.IMPORTANCE PtdSer receptors, such as TIM-1, are emerging as critical entry factors for many enveloped viruses. Most recently, hepatitis C virus and Zika virus have been added to a growing list. PtdSer receptors engage with enveloped viruses through the binding of PtdSer embedded in the viral envelope, defining them as GP-independent receptors. This GP-independent entry mechanism should effectively mediate the entry of all enveloped viruses, yet LASV GP-pseudotyped viruses were previously found to be unresponsive to PtdSer receptor enhancement in HEK 293T cells. Here, we demonstrate that LASV pseudovirions can utilize the PtdSer receptor TIM-1 but only in the absence of appropriately glycosylated alpha-dystroglycan (alpha DG), the high-affinity cell surface receptor for LASV. Our studies shed light on LASV receptor utilization and explain why previous studies performed with alpha-DG-expressing cells did not find that LASV pseudovirions utilize PtdSer receptors for virus uptake.