Significance Protease inhibitors targeting viral 3C-like protease are attractive therapeutic options for COVID-19. Here, we synthesized deuterated variants of a coronavirus protease inhibitor, GC376, and determined the therapeutic efficacy in a lethal mouse model. The transgenic mice infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a causative agent of COVID-19, develop lung pathology resembling that of severe COVID-19 patients and were used for antiviral drug testing. The deuterated variants of GC376 have improved potency against SARS-CoV-2 in in vitro assays. Furthermore, treatment with a deuterated variant starting at 24 h postinfection resulted in significantly increased survival of mice compared to vehicle-treated mice. The results suggest that deuterated variants have excellent potential as antiviral agents against SARS-CoV-2. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection continues to be a serious global public health threat. The 3C-like protease (3CLpro) is a virus protease encoded by SARS-CoV-2, which is essential for virus replication. We have previously reported a series of small-molecule 3CLpro inhibitors effective for inhibiting replication of human coronaviruses including SARS-CoV-2 in cell culture and in animal models. Here we generated a series of deuterated variants of a 3CLpro inhibitor, GC376, and evaluated the antiviral effect against SARS-CoV-2. The deuterated GC376 displayed potent inhibitory activity against SARS-CoV-2 in the enzyme- and the cell-based assays. The K18-hACE2 mice develop mild to lethal infection commensurate with SARS-CoV-2 challenge doses and were proposed as a model for efficacy testing of antiviral agents. We treated lethally infected mice with a deuterated derivative of GC376. Treatment of K18-hACE2 mice at 24 h postinfection with a derivative (compound 2) resulted in increased survival of mice compared to vehicle-treated mice. Lung virus titers were decreased, and histopathological changes were ameliorated in compound 2–treated mice compared to vehicle-treated mice. Structural investigation using high-resolution crystallography illuminated binding interactions of 3CLpro of SARS-CoV-2 and SARS-CoV with deuterated variants of GC376. Taken together, deuterated GC376 variants have excellent potential as antiviral agents against SARS-CoV-2.
【저자키워드】 SARS-CoV-2, Antiviral, protease inhibitors, K18-ACE2 mice, 【초록키워드】 COVID-19, Treatment, severe acute respiratory syndrome coronavirus 2, Efficacy, coronavirus, SARS-CoV, variant, Infection, animal models, 3CLpro, protease, severe acute respiratory syndrome Coronavirus, virus, antiviral drug, Antiviral effect, Replication, Protease inhibitor, survival, Viral, mice, Cell culture, Antiviral agents, Mild, virus replication, K18-hACE2 mice, respiratory, antiviral agent, inhibitor, change, human coronaviruses, Lung pathology, dose, High-resolution, therapeutic option, virus titers, causative agent, virus titer, acute respiratory syndrome, acute respiratory syndrome coronavirus, global public health, enzyme, Compound, therapeutic efficacy, increased survival, severe COVID-19 patients, transgenic mice, potency, inhibitory activity, binding interactions, lethal infection, effective, Postinfection, binding interaction, significantly increased, human coronavirus, develop, reported, assays, evaluated, treated, were used, histopathological, inhibiting, ameliorated, in vitro assays, severe COVID-19 patient, Significance, 【제목키워드】 Treatment, SARS-COV-2 infection, Protease inhibitor, survival, increase,