STING激动剂MSA-2和Mn2+体外抑制猪繁殖与呼吸综合征病毒复制

STING agonist MSA-2 and Mn2+ inhibit PRRSV replication in vitro

摘要:

背景 猪繁殖与呼吸综合征病毒(porcine reproductive and respiratory syndrome virus, PRRSV)是威胁全球养猪业健康发展的核心致病性病原体，其高变异性导致现有疫苗保护效果有限，亟需研发病毒病防治新策略。目的 靶向激活干扰素基因刺激因子已被证实具有抗病毒活性，但其对PRRSV的作用尚未明确。方法 本研究以PRRSV为对象，采用qRT-PCR、TCID₅₀测定及Western blotting等方法，评估新型STING激动剂MSA-2与Mn²⁺的体外抗PRRSV活性。结果 30 μmol/L MSA-2或80 μmol/L Mn²⁺处理MARC-145细胞后，与未处理细胞组相比，PRRSV RNA水平降低91.13% (P<0.000 1)或87.78% (P<0.000 1)；病毒滴度下降≥5.7 log₁₀ TCID₅₀ (P<0.000 1)或4.6 log₁₀ TCID₅₀ (P<0.000 1)；病毒N蛋白表达水平也显著下调，进一步研究发现，MSA-2和Mn²⁺均通过激活STING，诱导TBK1、IRF3及NF-κB磷酸化，并上调IFN-β、IFN-α等细胞因子的mRNA水平，从而抑制病毒复制。结论 本研究证实MSA-2与Mn²⁺有效抑制PRRSV复制，为开发新型抗PRRSV小分子提供了实验依据。

Abstract:

Background Porcine reproductive and respiratory syndrome virus (PRRSV) is a core pathogenic agent threatening the healthy development of the global pig industry. Its high variability limits the protective efficacy of existing vaccines, and there is an urgent need to develop new strategies for the prevention and treatment of diseases caused by this virus.Objective Although targeted activation of the stimulator of interferon genes (STING) has been confirmed to induce the antiviral activity, its activity against PRRSV remains unclear.Methods We evaluated the in vitro anti-PRRSV activities of the novel STING agonist MSA-2 and Mn²⁺ through qRT-PCR, TCID₅₀ assay, and Western blotting.Results The treatment of MARC-145 cells with 30 μmol/L MSA-2 or 80 μmol/L Mn²⁺ decreased the PRRSV RNA level by 91.13% (P<0.000 1) or 87.78% (P<0.000 1) and the virus titer by≥5.7 log₁₀ TCID₅₀ (P<0.000 1) or 4.6 log₁₀ TCID₅₀ (P<0.000 1) compared with the control group without treatment. Moreover, 30 μmol/L MSA-2 or 80 μmol/L Mn²⁺ downregulated the expression level of viral N protein. Further studies revealed that both MSA-2 and Mn²⁺ inhibited viral replication by activating STING, inducing the phosphorylation of TBK1, IRF3, and NF-κB, and upregulating the mRNA levels of cytokines such as IFN-β and IFN-α.Conclusion This study is the first to confirm that MSA-2 and Mn²⁺ effectively inhibit the replication of PRRSV, providing experimental evidence for the development of novel anti-PRRSV small molecules.