Key Laboratory of Livestock Infectious Diseases in Northeast China, Ministry of Education, College of Animal Science & Veterinary Medicine, Shenyang Agricultural University, Shenyang, China, No.120, Dongling Road, Shenhe District 110866, PR China
The Preventive and Control Center of Animal Disease of Liaoning Province, Liaoning Agricultural Development Service Center, No. 95, Renhe Road, Shenbei District, Shenyang 110164, PR China
Bioorg Med Chem. 2021 Apr 1;35:116055. doi: 10.1016/j.bmc.2021.116055. Epub 2021 Feb 10.
African swine fever (ASF) is a viral disease in swine that results in high mortality in domestic pigs and causes considerable economic losses. Currently, there is no effective vaccine or drugs available for treatment. Identification of new anti-ASFV drugs is urgently needed. Here, the pS273R protein of the African swine fever virus (ASFV) is a specific SUMO-1-like cysteine protease that plays an important role in its replication process. To inhibit virus replication and improve treatment options, a set of small-molecule compounds, targeted inhibitors against the ASFV pS273R protease, were obtained through molecular screening by homology modeling and molecular docking based on structural information of pS273R. Our results clearly demonstrated that the 14th carbon atom of the cysteinase inhibitor E-64 could form one CS covalent bond with the Cys 232 amino acid of the pS273R protease and seven additional hydrogen bonds to maintain a stable binding state. Simultaneously, cell viability, immunophenotyping, and in vitro enzyme activity inhibition assays were performed to comprehensively evaluate E-64 characteristics. Our findings demonstrated that 4 mmol/L E-64 could effectively inhibit the enzyme activity center of the pS273R protease by preventing pS273R protease from lysing pp62, while promoting the upregulation of immune-related cytokines at the transcription level. Moreover, cell viability results revealed that 4 mmol/L E-64 was not cytotoxic. Taken together, we identified a novel strategy to potentially prevent ASFV infection in pigs by blocking the activity of pS273R protease with a small-molecule inhibitor.
非洲猪瘟（ASF）是一种猪的病毒性疾病，会导致家猪高死亡率，并造成相当大的经济损失。目前，尚无有效的疫苗或药物可用于治疗。因此，急需寻找新的抗 ASF 药物。非洲猪瘟病毒（ASFV）的 pS273R 蛋白是一种特异性 SUMO-1 样半胱氨酸蛋白酶，在其复制过程中发挥重要作用。为了抑制病毒复制并改善治疗选择，我们通过同源建模的分子筛选和基于 pS273R 结构信息的分子对接获得了一组针对 ASFV pS273R 蛋白酶的小分子化合物靶向抑制剂。我们的结果清楚地表明，半胱氨酸酶抑制剂 E-64 的第 14 个碳原子可以与 pS273R 蛋白酶的 Cys232 氨基酸形成一个 CS 共价键，并与另外七个氢键保持稳定的结合状态。同时，进行了细胞活力、免疫表型和体外酶活性抑制测定，以全面评估 E-64 的特性。我们的研究结果表明，4mmol/L 的 E-64 可以通过阻止 pS273R 蛋白酶裂解 pp62 来有效抑制 pS273R 蛋白酶的酶活性中心，同时促进免疫相关细胞因子在转录水平的上调。此外，细胞活力结果表明，4mmol/L 的 E-64 没有细胞毒性。总之，我们确定了一种通过使用小分子抑制剂阻断 pS273R 蛋白酶的活性来预防猪 ASF 感染的新策略。
