According to the DrugVirus.info database , 13 of the antiviral compounds selected by the pharmacophore-based search showed activity against a total of 40 viruses in cell-culture, animal, and clinic models (Figure ). The other eight antiviral compounds were not in the database. A previous study did not identify any of these compounds as potential NSP15 inhibitors, and their top selected drugs did not show antiviral activity . Differences in methodology may explain these discrepancies of results. Specifically, Chandra and co-authors used NSP15 PDB ID 6W01 structure with a citrate ion ; we used crystal structure of NSP15 in complex with tipiracil that binds to NSP15 uracil site. We assume that the pharmacophore model generated on this protein structure includes the key features responsible for ligand interaction with residues in NSP15 active site. We did notice that tipiracil, the positive control, did not have a low free energy.