A viral RNA-dependent RNA polymerase inhibitor VV116 broadly inhibits human coronaviruses and has synergistic potency with 3CLpro inhibitor nirmatrelvir

Cell lines and viruses

African green monkey kidney Vero E6 cells (ATCC-1586), RD, Huh-7, HEK293T-hACE2-TMPRSS2 were maintained in Dulbecco’s modified Eagle’s medium (DMEM) with 10% fetal bovine serum (FBS) and 1% penicillin–streptomycin antibiotics. MRC5 was maintained in Minimum Essential Medium (MEM) with 10% fetal bovine serum (FBS) and 1% penicillin–streptomycin antibiotics. Cells were kept at 37 °C in a 5% CO₂ atmosphere. The strains Delta variant (B.1.617.2, IVCAS6.7585), omicron BA.1 variant (IVCAS6.7600), and omicron BA.5 variant (IVCAS6.8981) of SARS-CoV-2 were obtained…