Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the etiologic agent for the global COVID-19 pandemic, triggers the formation of endoplasmic reticulum (ER)-derived replication organelles, including double-membrane vesicles (DMVs), in the host cell to support viral replication. Here, we clarify how SARS-CoV-2 hijacks host factors to construct the DMVs. We show that the ER morphogenic proteins reticulon-3 (RTN3) and RTN4 help drive DMV formation, enabling viral replication, which leads to productive infection. Different SARS-CoV-2 variants, including the delta variant, use the RTN-dependent pathway to promote infection. Mechanistically, our results reveal that the membrane-embedded reticulon homology domain (RHD) of the RTNs is sufficient to functionally support viral replication and physically engage NSP3 and NSP4, two viral non-structural membrane proteins known to induce DMV formation. Our findings thus identify the ER morphogenic RTN3 and RTN4 membrane proteins as host factors that help promote the biogenesis of SARS-CoV-2-induced DMVs, which can act as viral replication platforms.

中文翻译：

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网织体促进内质网衍生的双膜囊泡的形成，从而促进 SARS-CoV-2 的复制

严重急性呼吸综合征冠状病毒-2 (SARS-CoV-2) 是全球 COVID-19 大流行的病原体，可在体内触发内质网 (ER) 衍生的复制细胞器，包括双膜囊泡 (DMV) 的形成。宿主细胞支持病毒复制。在这里，我们阐明了 SARS-CoV-2 如何劫持宿主因子来构建 DMV。我们发现内质网形态发生蛋白 reticulon-3 (RTN3) 和 RTN4 有助于驱动 DMV 形成，从而实现病毒复制，从而导致有效感染。不同的 SARS-CoV-2 变体（包括 delta 变体）使用 RTN 依赖性途径来促进感染。从机制上讲，我们的结果表明，RTN 的膜嵌入网织同源结构域 (RHD) 足以在功能上支持病毒复制并物理上接合 NSP3 和 NSP4（已知可诱导 DMV 形成的两种病毒非结构膜蛋白）。因此，我们的研究结果将内质网形态发生 RTN3 和 RTN4 膜蛋白确定为宿主因子，有助于促进 SARS-CoV-2 诱导的 DMV 的生物合成，从而充当病毒复制平台。