Innovation Team of Small Animal Infectious Disease, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai 200241, China.
Laboratory of Virology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands.
Viruses. 2021 Mar 5;13(3):409. doi: 10.3390/v13030409.
The mitochondrial antiviral-signaling protein (MAVS, also known as VISA, IPS-1, or CARDIF) plays an essential role in the type I interferon (IFN) response and in retinoic acid-inducible gene I (RIG-I) mediated antiviral innate immunity in mammals. In this study, the caprine MAVS gene (caMAVS, 1566 bp) was identified and cloned. The caMAVS shares the highest amino acid similarity (98.1%) with the predicted sheep MAVS. Confocal microscopy analysis of partial deletion mutants of caMAVS revealed that the transmembrane and the so-called Non-Characterized domains are indispensable for intracellular localization to mitochondria. Overexpression of caMAVS in caprine endometrial epithelial cells up-regulated the mRNA levels of caprine interferon-stimulated genes. We concluded that caprine MAVS mediates the activation of the type I IFN pathway. We further demonstrated that both the CARD-like domain and the transmembrane domain of caMAVS were essential for the activation of the IFN-β promotor. The interaction between caMAVS and caprine RIG-I and the vital role of the CARD and NC domain in this interaction was demonstrated by co-immunoprecipitation. Upon infection with the Peste des Petits Ruminants Virus (PPRV, genus Morbillivirus), the level of MAVS was greatly reduced. This reduction was prevented by the addition of the proteasome inhibitor MG132. Moreover, we found that viral protein V could interact and colocalize with MAVS. Together, we identified caMAVS as a RIG-I interactive protein involved in the activation of type I IFN pathways in caprine cells and as a target for PPRV immune evasion.
线粒体抗病毒信号蛋白（MAVS，也称为 VISA、IPS-1 或 CARDIF）在哺乳动物的 I 型干扰素（IFN）反应和视黄酸诱导基因 I（RIG-I）介导的抗病毒先天免疫中发挥着重要作用。在本研究中，鉴定并克隆了山羊 MAVS 基因（caMAVS，1566bp）。caMAVS 与预测的绵羊 MAVS 具有最高的氨基酸相似性（98.1%）。caMAVS 的部分缺失突变体的共聚焦显微镜分析表明，跨膜和所谓的非特征性结构域对于线粒体的细胞内定位是必不可少的。caMAVS 在山羊子宫内膜上皮细胞中的过表达上调了山羊干扰素刺激基因的 mRNA 水平。我们得出结论，山羊 MAVS 介导 I 型 IFN 途径的激活。我们进一步证明，caMAVS 的 CARD 样结构域和跨膜结构域对于 IFN-β 启动子的激活都是必不可少的。通过共免疫沉淀证明了 caMAVS 与山羊 RIG-I 的相互作用以及 CARD 和 NC 结构域在这种相互作用中的重要作用。感染小反刍兽疫病毒（PPRV，属麻疹病毒）后，MAVS 水平大大降低。加入蛋白酶体抑制剂 MG132 可防止这种降低。此外，我们发现病毒蛋白 V 可以与 MAVS 相互作用并共定位。总之，我们确定 caMAVS 是一种与 RIG-I 相互作用的蛋白，参与山羊细胞中 I 型 IFN 途径的激活，并作为 PPRV 免疫逃逸的靶点。
