Inhibition of Porcine Epidemic Diarrhea Virus Replication and Viral 3C-Like Protease by Quercetin

For the last decade, porcine epidemic diarrhea virus (PEDV) variant strains have caused severe damage to the global pig industry. Until now, no effective antivirals have been developed for the therapeutic treatment of PEDV infection. In the present study, we found that quercetin significantly suppressed PEDV infection at noncytotoxic concentrations. A molecular docking study indicated that quercetin might bind the active site and binding pocket of PEDV 3C-like protease (3CL(pro)). Surface plasmon resonance (SPR) analysis revealed that quercetin exhibited a binding affinity to PEDV 3CL(pro). Based on the results of the fluorescence resonance energy transfer (FRET) assay, quercetin was proven to exert an inhibitory effect on PEDV 3CL(pro). Since coronavirus 3CL(pro) is an important drug target and participates in the viral replication process, quercetin should be developed as a novel drug in the control of PEDV infection.