Virus-like vesicles (VLV) are infectious, self-propagating alphavirus-vesiculovirus hybrid vaccine vectors that can be engineered to express foreign antigens to elicit a protective immune response. VLV are highly immunogenic and nonpathogenic in vivo, and we hypothesize that the unique replication and structural characteristics of VLV efficiently induce an innate antiviral response that enhances immunogenicity and limits replication and spread of the vector. We found that VLV replication is inhibited by interferon (IFN)-α, IFN-γ, and IFN-λ, but not by tumor necrosis factor-α. In cell culture, VLV infection activated IFN production and expression of IFN-stimulated genes (ISGs), such as MXA, ISG15, and IFI27, which were dependent on replication of the evolved VLV-encoded Semliki Forest virus replicon. Knockdown of the pattern recognition receptors, retinoic acid-inducible gene I and melanoma differentiation-associated protein 5 or their intermediary signaling protein mitochondrial antiviral-signaling protein (MAVS) blocked IFN production. Furthermore, ISG expression in VLV-infected cells was dependent on IFN receptor signaling through the Janus kinase (JAK) tyrosine kinases and phosphorylation of the STAT1 protein, and JAK inhibition restored VLV replication in otherwise uninfectable cell lines. This work provides new insight into the mechanism of innate antiviral responses to a hybrid virus-based vector and provides the basis for future characterization of the platform's safety and adjuvant-like effects in vivo. [Figure: see text].

中文翻译：

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混合甲病毒-弹状病毒疫苗平台的先天免疫激活机制。

病毒样囊泡 (VLV) 是具有传染性的、自我繁殖的甲病毒-囊泡病毒杂交疫苗载体，可以设计成表达外来抗原以引发保护性免疫反应。VLV 在体内具有高度免疫原性和非致病性，我们假设 VLV 独特的复制和结构特征有效地诱导了先天抗病毒反应，从而增强了免疫原性并限制了载体的复制和传播。我们发现 VLV 复制受到干扰素 (IFN)-α、IFN-γ 和 IFN-λ 的抑制，但不受肿瘤坏死因子-α 的抑制。在细胞培养中，VLV 感染激活了 IFN 产生和 IFN 刺激基因 (ISG) 的表达，例如 MXA、ISG15 和 IFI27，这些基因依赖于进化的 VLV 编码的 Semliki Forest 病毒复制子的复制。模式识别受体的击倒，视黄酸诱导基因 I 和黑色素瘤分化相关蛋白 5 或其中间信号蛋白线粒体抗病毒信号蛋白 (MAVS) 阻断了 IFN 的产生。此外，VLV 感染细胞中的 ISG 表达依赖于通过 Janus 激酶 (JAK) 酪氨酸激酶和 STAT1 蛋白磷酸化的 IFN 受体信号传导，并且 JAK 抑制恢复了 VLV 在其他不可感染细胞系中的复制。这项工作提供了对基于混合病毒的载体的先天抗病毒反应机制的新见解，并为该平台的安全性和体内佐剂样效应的未来表征提供了基础。[图：见正文]。