Non-structural protein 1 (NS1) of influenza virus is a multifunctional protein that plays an important role in virus replication and virulence. In this study, an acetylation modification was identified at the K108 residue of the NS1 protein of H1N1 influenza virus. To further explore the function of the K108 acetylation modification of the NS1 protein, a deacetylation-mimic mutation (K108R) and a constant acetylation-mimic mutation (K108Q) were introduced into the NS1 protein in the background of A/WSN/1933 H1N1 (WSN), resulting in two mutant viruses (WSN-NS1-108R and WSN-NS1-108Q). In vitro and mouse studies showed that the deacetylation-mimic mutation K108R in the NS1 protein attenuated the replication and virulence of WSN-NS1-108R, while the constant acetylation-mimic mutant virus WSN-NS1-108Q showed similar replication and pathogenicity as the wild-type WSN virus (WSN-wt). The results indicated that acetylation at K108 of the NS1 protein has an important role in the replication and virulence of influenza virus. To further explore the potential mechanism, the type I interferon (IFN-I) antagonistic activity of the three NS1 proteins (NS1-108Q, NS1-108R, and NS1-wt) was compared in cells, which showed that the K108R mutation significantly attenuated the IFN-β antagonistic activity of the NS1 protein compared with NS1-wt and NS1-108Q. Both NS1-wt and NS1-108Q inhibited the IFN-β response activated by RIG-I CARD domain, MAVS, TBK1, and IRF3 more efficiently than the NS1-108R protein in cells. Taken together, the results indicated that acetylation at NS1 K108 is important for the IFN antagonistic activity of the NS1 protein and virulence of the influenza virus.

中文翻译：

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NS1蛋白在K108的乙酰化对于流感病毒的复制和毒力很重要。

流感病毒的非结构蛋白1（NS1）是一种多功能蛋白，在病毒复制和毒力中起重要作用。在这项研究中，乙酰化修饰被确定在H1N1流感病毒的NS1蛋白的K108残基上。为了进一步探索NS1蛋白的K108乙酰化修饰的功能，在A / WSN / 1933 H1N1（背景中，将去乙酰化模拟突变（K108R）和恒定乙酰化模拟突变（K108Q）引入了NS1蛋白中（ WSN），产生两种突变病毒（WSN-NS1-108R和WSN-NS1-108Q）。体外和小鼠研究表明，NS1蛋白中的脱乙酰基模拟突变K108R减弱了WSN-NS1-108R的复制和毒力，恒定乙酰化模拟突变病毒WSN-NS1-108Q与野生型WSN病毒（WSN-wt）具有相似的复制和致病性。结果表明，NS1蛋白在K108处的乙酰化在流感病毒的复制和毒力中具有重要作用。为了进一步探讨其潜在机制，比较了三种NS1蛋白（NS1-108Q，NS1-108R和NS1-wt）在细胞中的I型干扰素（IFN-I）拮抗活性，结果表明K108R突变显着减弱了与NS1-wt和NS1-108Q相比，NS1蛋白具有IFN-β拮抗活性。与细胞中的NS1-108R蛋白相比，NS1-wt和NS1-108Q都更有效地抑制了RIG-1 CARD域，MAVS，TBK1和IRF3激活的IFN-β反应。在一起