Department of Microbiology and Immunology, Dalhousie University, 5850 College Street, Halifax, NS B3H 4R2, Canada.
Department of Community Health and Epidemiology, Dalhousie University, 5790 University Avenue, Halifax, NS B3H 1V7, Canada.
Viruses. 2017 Dec 18;9(12):388. doi: 10.3390/v9120388.
Eukaryotic translation initiation factor 4A (eIF4A) is a helicase that facilitates assembly of the translation preinitiation complex by unwinding structured mRNA 5' untranslated regions. Pateamine A (PatA) and silvestrol are natural products that disrupt eIF4A function and arrest translation, thereby triggering the formation of cytoplasmic aggregates of stalled preinitiation complexes known as stress granules (SGs). Here we examined the effects of eIF4A inhibition by PatA and silvestrol on influenza A virus (IAV) protein synthesis and replication in cell culture. Treatment of infected cells with either PatA or silvestrol at early times post-infection resulted in SG formation, arrest of viral protein synthesis and failure to replicate the viral genome. PatA, which irreversibly binds to eIF4A, sustained long-term blockade of IAV replication following drug withdrawal, and inhibited IAV replication at concentrations that had minimal cytotoxicity. By contrast, the antiviral effects of silvestrol were fully reversible; drug withdrawal caused rapid SG dissolution and resumption of viral protein synthesis. IAV inhibition by silvestrol was invariably associated with cytotoxicity. PatA blocked replication of genetically divergent IAV strains, suggesting common dependence on host eIF4A activity. This study demonstrates that the core host protein synthesis machinery can be targeted to block viral replication.
真核翻译起始因子 4A（eIF4A）是一种解旋酶，通过解开结构 mRNA 5'非翻译区来促进翻译起始复合物的组装。Pateamine A（PatA）和 silvestrol 是天然产物，可破坏 eIF4A 功能并阻断翻译，从而引发翻译起始复合物停滞的细胞质聚集体形成，称为应激颗粒（SGs）。在这里，我们研究了 PatA 和 silvestrol 对细胞培养中甲型流感病毒（IAV）蛋白合成和复制的抑制作用。在感染后早期用 PatA 或 silvestrol 处理感染的细胞会导致 SG 形成、病毒蛋白合成停滞和病毒基因组无法复制。PatA 不可逆地与 eIF4A 结合，在停药后持续长期阻断 IAV 复制，并以最小细胞毒性浓度抑制 IAV 复制。相比之下，silvestrol 的抗病毒作用是完全可逆的；停药会导致 SG 迅速溶解并恢复病毒蛋白合成。silvestrol 抑制 IAV 复制始终与细胞毒性有关。PatA 阻断了遗传上不同的 IAV 株的复制，表明它们普遍依赖宿主 eIF4A 活性。这项研究表明，可以针对宿主蛋白合成机制来阻断病毒复制。
