Fusion-active glycoprotein G mediates the cytotoxicity of vesicular stomatitis virus M mutants lacking host shut-off activity
Fusion-active glycoprotein G mediates the cytotoxicity of vesicular stomatitis virus M mutants lacking host shut-off activity
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DOI：
10.1099/vir.0.023978-0
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发表时间：
2010-11-01
影响因子：
3.8
通讯作者：
Zimmer, Gert
中科院分区：
文献类型：
--
作者：
Hoffmann, Markus;Wu, Yuan-Ju;Zimmer, Gert
水疱性口炎病毒（VSV）的细胞致病性主要归因于病毒基质(M)蛋白的宿主关闭活性，该活性抑制核转录和核胞质RNA转运，从而有效抑制I型干扰素（IFN）的合成。来自持续vsv感染细胞的M蛋白被证明含有与IFN诱导有关的特征氨基酸替换（M51R， V221F和S226R）。该研究表明，含有M51R替代的重组VSV感染人成纤维细胞导致IFN诱导，而V221F和S226R替代均不影响IFN诱导表型。只有当V221F与S226R结合时，M蛋白的宿主关闭活性才会被取消，IFN会被诱导，而不依赖于M51R。先前与VSV细胞毒性有关的M33A取代不影响宿主关闭活性。含有所有四种氨基酸取代的m突变型VSV在Vero细胞和ifn原代成纤维细胞中都保留了细胞毒性。感染细胞的死亡与巨大多核细胞的形成有关，提示VSV - G蛋白的融合活性参与其中。因此，表达融合缺陷G蛋白或缺失G基因的m突变型VSV在Vero细胞和小鼠海马切片培养中表现出显著降低的细胞毒性，并引起长期感染。相比之下，表达野生型M蛋白的g缺失VSV仍然具有细胞毒性。这些发现表明M蛋白的宿主关闭活性主导VSV的细胞毒性，而融合活性G蛋白主要负责对M突变型VSV保留细胞毒性。
The cytopathogenicity of vesicular stomatitis virus (VSV) has been attributed mainly to the host shut-off activity of the viral matrix (M) protein, which inhibits both nuclear transcription and nucleocytoplasmic RNA transport, thereby effectively suppressing the synthesis of type I interferon (IFN). The M protein from persistently VSV-infected cells was shown to harbour characteristic amino acid substitutions (M51R, V221F and S226R) implicated in IFN induction. This study demonstrates that infection of human fibroblasts with recombinant VSV containing the M51R substitution resulted in IFN induction, whereas neither the V221F nor the S226R substitution effected an IFN-inducing phenotype. Only when V221F was combined with S226R were the host shut-off activity of the M protein abolished and IFN induced, independently of M51R. The M33A substitution, previously implicated in VSV cytotoxicity, did not affect host shutoff activity. M-mutant VSV containing all four amino acid substitutions retained cytotoxic properties in both Vero cells and IFN-competent primary fibroblasts. Infected-cell death was associated with the formation of giant polynucleated cells, suggesting that the fusion activity of the VSV G protein was involved. Accordingly, M-mutant VSV expressing a fusion-defective G protein or with a deletion of the G gene showed significantly reduced cytotoxic properties and caused long-lasting infections in Vero cells and mouse hippocampal slice cultures. In contrast, a G-deleted VSV expressing wild-type M protein remained cytotoxic. These findings indicate that the host shut-off activity of the M protein dominates VSV cytotoxicty, whilst the fusion-active G protein is mainly responsible for the cytotoxicity remaining with M-mutant VSV.