Pathogenic coronaviruses are a major threat to global public health, as exemplified by severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV), and the newly emerged SARS-CoV-2, the causative agent of coronavirus disease 2019 (COVID-19). We describe herein the structure-guided optimization of a series of inhibitors of the coronavirus 3C-like protease (3CLpro), an enzyme essential for viral replication. The optimized compounds were effective against several human coronaviruses including MERS-CoV, SARS-CoV, and SARS-CoV-2 in an enzyme assay and in cell-based assays using Huh-7 and Vero E6 cell lines. Two selected compounds showed antiviral effects against SARS-CoV-2 in cultured primary human airway epithelial cells. In a mouse model of MERS-CoV infection, administration of a lead compound 1 day after virus infection increased survival from 0 to 100% and reduced lung viral titers and lung histopathology. These results suggest that this series of compounds has the potential to be developed further as antiviral drugs against human coronaviruses.

致病性冠状病毒是对全球公共卫生的主要威胁，例如严重急性呼吸综合征冠状病毒（SARS-CoV），中东呼吸综合征冠状病毒（MERS-CoV）和新近出现的SARS-CoV-2（该病的致病因子）就是例证。 2019年冠状病毒病（COVID-19）。我们在这里描述了一系列冠状病毒3C样蛋白酶（3CLpro）的抑制剂的结构指导优化，这是病毒复制所必需的酶。优化的化合物在酶测定以及使用Huh-7和Vero E6细胞系的基于细胞的测定中可有效抵抗几种人类冠状病毒，包括MERS-CoV，SARS-CoV和SARS-CoV-2。两种选定的化合物在培养的原代人气道上皮细胞中表现出针对SARS-CoV-2的抗病毒作用。在MERS-CoV感染的小鼠模型中，病毒感染后1天服用前导化合物可使生存率从0％提高到100％，并降低肺病毒滴度和肺组织病理学。这些结果表明，该系列化合物具有作为抗人冠状病毒的抗病毒药物的潜力。