State Key Laboratory of Veterinary Etiological Biology, National Foot and Mouth Diseases Reference Laboratory, Key Laboratory of Animal Virology of Ministry of Agriculture, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China.
State Key Laboratory of Veterinary Etiological Biology, National Foot and Mouth Diseases Reference Laboratory, Key Laboratory of Animal Virology of Ministry of Agriculture, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
J Virol. 2019 May 15;93(11). doi: 10.1128/JVI.00124-19. Print 2019 Jun 1.
The role of nucleotide-binding oligomerization domain 2 (NOD2) in foot-and-mouth disease virus (FMDV)-infected cells remains unknown. Here, we showed that FMDV infection activated NOD2-mediated beta interferon (IFN-β) and nuclear factor-κB (NF-ĸB) signaling pathways. NOD2 inhibited FMDV replication in the infected cells. FMDV infection triggered NOD2 transcription, while it reduced the abundance of NOD2 protein. Our results revealed that FMDV 2B, 2C, and 3C proteinase (3C) were responsible for the decrease in NOD2 protein levels. 3C is a viral proteinase that can cleave multiple host proteins and limit protein synthesis. Our previous studies determined that FMDV 2B suppressed protein expression of RIG-I and LGP2. Here, we found that 3C and 2B also decreased NOD2 expression. However, this is the first report that 2C induced the reduction of NOD2 protein levels. We determined that both 2B- and 2C-induced decreases in NOD2 were independent of the cleavage of host eukaryotic translation initiation factor 4 gamma (eIF4G), induction of cellular apoptosis, or proteasome, lysosome, and caspase pathways. The interactions between NOD2 and 2B or 2C were observed in the context of viral infection. The carboxyl-terminal amino acids 105 to 114 and 135 to 144 of 2B were essential for the reduction of NOD2, while the residues 105 to 114 were required for the interaction. Amino acids 116 to 260 of the carboxyl terminus of 2C were essential for the interaction, while truncated 2C mutants did not reduce NOD2. These data suggested novel antagonistic mechanisms of FMDV that were mediated by 2B, 2C, and 3C proteins. NOD2 was identified as a cytoplasmic viral pattern recognition receptor in 2009. Subsequently, many viruses were reported to activate NOD2-mediated signaling pathways. This study demonstrated that FMDV infection activated NOD2-mediated IFN-β and NF-ĸB signaling pathways. Host cells have developed multiple strategies against viral infection; however, viruses have evolved many strategies to escape host defenses. FMDV has evolved multiple mechanisms to inhibit host type I IFN production. Here, we showed that NOD2 suppressed FMDV replication during viral infection. FMDV 2B, 2C, and 3C decreased NOD2 protein expression by different mechanisms to promote viral replication. This study provided new insight into the immune evasion mechanisms mediated by FMDV and identified 2B, 2C, and 3C as antagonistic factors for FMDV to evade host antiviral responses.
核苷酸结合寡聚化结构域 2（NOD2）在口蹄疫病毒（FMDV）感染细胞中的作用尚不清楚。在这里，我们表明 FMDV 感染激活了 NOD2 介导的β干扰素（IFN-β）和核因子-κB（NF-κB）信号通路。NOD2 抑制了感染细胞中的 FMDV 复制。FMDV 感染触发了 NOD2 的转录，同时降低了 NOD2 蛋白的丰度。我们的结果表明，FMDV 2B、2C 和 3C 蛋白酶（3C）负责降低 NOD2 蛋白水平。3C 是一种病毒蛋白酶，可切割多种宿主蛋白并限制蛋白质合成。我们之前的研究确定 FMDV 2B 抑制了 RIG-I 和 LGP2 的蛋白表达。在这里，我们发现 3C 和 2B 也降低了 NOD2 的表达。然而，这是第一个报道 2C 诱导 NOD2 蛋白水平降低的报告。我们确定 2B 和 2C 诱导的 NOD2 减少均不依赖于宿主真核起始因子 4 伽马（eIF4G）的切割、细胞凋亡的诱导或蛋白酶体、溶酶体和半胱天冬酶途径。在病毒感染的情况下观察到 NOD2 与 2B 或 2C 的相互作用。2B 的羧基末端氨基酸 105 至 114 和 135 至 144 对于 NOD2 的减少是必需的，而 105 至 114 氨基酸对于相互作用是必需的。2C 羧基末端 116 至 260 个氨基酸残基对于相互作用是必需的，而截短的 2C 突变体不能减少 NOD2。这些数据表明 FMDV 通过 2B、2C 和 3C 蛋白介导了新的拮抗机制。NOD2 于 2009 年被鉴定为细胞质病毒模式识别受体。随后，许多病毒被报道激活了 NOD2 介导的信号通路。本研究表明，FMDV 感染激活了 NOD2 介导的 IFN-β 和 NF-κB 信号通路。宿主细胞已经开发出多种针对病毒感染的策略；然而，病毒已经进化出许多逃避宿主防御的策略。FMDV 已经进化出多种机制来抑制宿主 I 型 IFN 的产生。在这里，我们表明 NOD2 在病毒感染过程中抑制了 FMDV 的复制。FMDV 2B、2C 和 3C 通过不同的机制降低 NOD2 蛋白表达，从而促进病毒复制。本研究为 FMDV 介导的免疫逃避机制提供了新的见解，并确定 2B、2C 和 3C 是 FMDV 逃避宿主抗病毒反应的拮抗因子。
