PF-00835231 broadly inhibits swine Alpha-coronavirus, including emerging SADS-CoV

Swine Alpha-coronaviruses are one of the most destructive pathogens affecting the swine industries across the world. Swine Alpha-coronaviruses include transmissible gastroenteritis virus (TGEV), porcine epidemic diarrhea virus, porcine respiratory coronavirus, and swine acute diarrhea syndrome coronavirus (SADS-CoV). Thus far, swine Alpha-coronaviruses treatment options are very limited. Therefore, the identification of safe and effective treatment of swine Alpha-coronaviruses is urgently needed. In the current study, we screened a library of 240 FDA-approved compounds for antiviral activity against TGEV. Among screening, the 3CL protease inhibitor PF-00835231 was shown to dramatically inhibit TGEV replication in vitro systems. Mechanistically, PF-00835231 inhibits nonstructural protein 5 (Nsp5) protease activity targeting the cleavage at Nsp5-Nsp6 of TGEV. Additionally, PF-00835231 exhibited the potent broad-spectrum swine Alpha-coronaviruses antiviral activity. Treatment of PF-00835231 in mice not only blocks SADS-CoV deadly infection but also dramatically reduces viral copies. Taken together, our study provides evidence that PF-00835231 may control of the current swine Alpha-coronaviruses and emerging swine Alpha-coronaviruses in the future.IMPORTANCEThe COVID-19 pandemic has induced tremendous efforts to develop therapeutic strategies that target Beta-coronavirus including SARS-CoV-2. 3CL protease of Beta-coronavirus has been as a drug target for developing antiviral drugs. However, 3CL protease is not conserved in Alpha-coronavirus and Beta-coronavirus with only 44% amino acid similarity. Therefore, an inhibitor that prevents Alpha-coronaviruses infection is urgently needed. Swine Alpha-coronaviruses are one of the most destructive pathogens affecting the swine industries across the world. Swine herds with coronavirus diarrhea showed a high rate of co-infection between different Alpha-coronavirus. Our study, for the first time, showed that PF-00835231 inhibits swine Alpha-coronavirus infection. At the mechanistic level, we experimentally identified that PF-00835231 inhibits nonstructural protein 5 (Nsp5) protease activity targeting the cleavage at Nsp5-Nsp6 of Alpha-coronaviruses.