State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730046, China.
Lanzhou University Second Hospital, Department of Radiology, Lanzhou 730030, China.
Vet Microbiol. 2022 Dec;275:109594. doi: 10.1016/j.vetmic.2022.109594. Epub 2022 Oct 29.
Senecavirus A (SVA) is a newly emerging etiological agent of vesicular disease associated with sow abortion and acute piglet death, causing devastating economic consequences to global pig industry. IFN-induced protein with tetratricopeptide repeats (IFIT) genes are versatile in combating a variety of viruses, but the detailed mechanisms-of-action against SVA is unexplored. Transcriptomic analysis and immunoblot revealed high abundance of IFIT transcripts and proteins following SVA infection, initially implying the correlation between IFITs and SVA. Type I IFNs restricted SVA replication accompanied with substantial elevation of IFIT expression, potentializing IFITs as anti-SVA effectors downstream of IFN signaling. Gain-of-function assay demonstrated that IFIT3 rather than IFIT1/2 potently inhibited SVA replication, which was consistently verified by SVA strain SVV CH-FJ-2017 by TCID titration and an eGFP-tagged recombinant SVA using fluorescent microscopy. Afterwards, IFIT3 disrupted SVA life cycle at the early stage of virus binding and internalization, and at the late stage of virus assembly and release, as quantified by copy number and transmission electron microscopy, respectively. Directly transfecting SVA infectious RNA in IFIT3-overexpressed cells bypassed its antiviral activity, further suggesting that IFIT3 targeted viral life cycle beyond RNA replication. Further investigations showed that IFIT3 overexpression was incapable of regulating host immune responses against pathogens. Those results identified IFIT3 as a potent inhibitor of SVA and implicated IFIT3 pathway in the regulation of virus entry/assembly. In short, IFIT3 exerted significant inhibitory effects on the replication and spread of SVA, and played different functions in the life cycle of SVA.
塞尼卡病毒 A（SVA）是一种新出现的与母猪流产和仔猪急性死亡相关的疱疹病毒病原体，给全球养猪业带来了毁灭性的经济后果。干扰素诱导的含有四肽重复的蛋白（IFIT）基因在对抗多种病毒方面具有多功能性，但针对 SVA 的详细作用机制尚不清楚。转录组分析和免疫印迹显示，SVA 感染后 IFIT 转录本和蛋白的丰度很高，最初表明 IFITs 与 SVA 之间存在相关性。I 型干扰素限制了 SVA 的复制，同时 IFIT 表达水平显著升高，这使得 IFITs 成为 IFN 信号下游的抗 SVA 效应因子。功能获得实验表明，IFIT3 而非 IFIT1/2 能够强烈抑制 SVA 的复制，这通过 TCID50 滴定和荧光显微镜检测到的带有 eGFP 标签的重组 SVA，对 SVV CH-FJ-2017 株进行验证后得到了一致的结果。随后，IFIT3 在病毒结合和内化的早期阶段以及病毒组装和释放的晚期阶段破坏了 SVA 的生命周期，这分别通过拷贝数和透射电子显微镜进行了量化。在 IFIT3 过表达细胞中转染 SVA 传染性 RNA 绕过了其抗病毒活性，进一步表明 IFIT3 靶向病毒生命周期超出了 RNA 复制。进一步的研究表明，IFIT3 过表达不能调节宿主对病原体的免疫反应。这些结果确定了 IFIT3 是 SVA 的有效抑制剂，并暗示了 IFIT3 途径在病毒进入/组装的调节中发挥作用。简而言之，IFIT3 对 SVA 的复制和传播具有显著的抑制作用，并在 SVA 的生命周期中发挥不同的功能。
