Data_Sheet_1_DDX56 inhibits PRV replication through regulation of IFN-β signaling pathway by targeting cGAS.doc

Pseudorabies virus (PRV) is an agent of Aujeszky's disease, and causes great economic losses to pig farming. Re-outburst of pseudorabies implies that new control measures are urgently needed. We show here that DDX56 possesses the ability to inhibit PRV replication in vitro, which may be an important factor for PRV infection. Overexpression of DDX56 inhibited PRV genomic DNA transcription and lower titers of PRV infection in PK15 cells, whereas down-regulation of the DDX56 expression had a promotion role on virus replication. Further study demonstrated that DDX56 exerted its proliferation-inhibitory effects of PRV through up-regulating cGAS-STING-induced IFN-β expression. Moreover, we found that DDX56 could promote cGAS expression and direct interaction also existed between DDX56 and cGAS. Based on this, DDX56-regulated IFN-β pathway may be targeted at cGAS. To verify this, down-regulated cGAS expression in DDX56 over-expression cells was performed. Results indicated that knockdown of cGAS expression could abrogate the inhibition role of DDX56 on PRV proliferation and weaken the effect of DDX56 on IFN-β expression. In addition, DDX56 played a promotion role in IRF3 phosphorylation and nucleus translocation. Altogether, our results highlight DDX56's antiviral role in PRV infection, and our findings contribute to a better understanding of host factors controlling PRV replication.

伪狂犬病病毒（Pseudorabies virus, PRV）是奥耶茨基病（Aujeszky's disease）的病原，可给养猪产业造成巨额经济损失。伪狂犬病疫情复燃意味着亟需研发新型防控策略。本研究证实，DDX56在体外具备抑制PRV增殖的能力，该蛋白可能是参与PRV感染过程的重要宿主因子。在PK15细胞中过表达DDX56可抑制PRV基因组DNA的转录，并降低病毒感染滴度；反之，下调DDX56的表达则会促进病毒增殖。进一步研究显示，DDX56通过上调环鸟苷酸-腺苷酸合成酶-干扰素基因刺激蛋白（cGAS-STING）通路介导的干扰素-β（IFN-β）表达，发挥其抑制PRV增殖的作用。此外，本研究发现DDX56可促进cGAS的表达，且DDX56与cGAS之间存在直接相互作用。据此推测，DDX56调控的IFN-β通路可能以cGAS为作用靶点。为验证该推测，本研究在DDX56过表达的细胞中下调了cGAS的表达，结果显示，敲低cGAS的表达可抵消DDX56对PRV增殖的抑制作用，并削弱DDX56对IFN-β表达的调控效应。另外，DDX56可促进干扰素调节因子3（IRF3）的磷酸化及其核转位。综上，本研究揭示了DDX56在PRV感染过程中的抗病毒作用，相关发现有助于深入解析调控PRV增殖的宿主因子机制。