Journal: Journal of Virology
Article Title: Potent in vitro synergistic antiviral effects of the pan-coronavirus fusion inhibitor EK1 in combination with RBD-specific antibodies or M pro inhibitors
doi: 10.1128/jvi.00076-26
Figure Lengend Snippet: Synergistic inhibition of authentic SARS-CoV-2 BA.2 and HCoV-OC43 by dual antiviral combinations. ( A ) Crystal structure of the M pro active site (PDB ID: 7CAM ). The protease is shown as a semi-transparent surface in gray, with the inhibitor-binding cleft highlighted in green. ( B ) Binding sites of M pro with PF-07321332 (PDB ID: 7VH8) in green, RAY1216 (PDB ID: 8IGN ) in yellow, and S-217622 (PDB ID: 8HEF ) in orange. ( C–H ) Dose-response analyses of the fusion inhibitor EK1 in combination with three distinct M pro inhibitors against authentic SARS-CoV-2 BA.2 ( C–E ) and HCoV-OC43 ( F–H ). In each panel, EK1 and the respective M pro inhibitor were tested both individually and as fixed-ratio combinations (molar ratios: PF-07321332, 20:3 for BA.2 and 25:4 for OC43; RAY1216, 4:1 for BA.2 and 25:1 for OC43; S-217622, 4:1 for BA.2 and 25:1 for OC43). Viral inhibition was quantified by fluorescent plaque assay (BA.2), and cell viability was assessed using the cell counting kit-8 (CCK-8) assay (OC43) at 48 h post-infection. Data represent mean ± SD from three independent experiments ( n = 3).
Article Snippet: The small-molecule M pro inhibitors nirmatrelvir (PF-07321332), RAY1216, and ensitrelvir (S-217622) were purchased from MedChemExpress (Shanghai, China).
Techniques: Inhibition, Binding Assay, Plaque Assay, Cell Counting, CCK-8 Assay, Infection