AVG-233 is a potent, orally active RNA dependent RNA polymerase (RdRp) inhibitor. AVG-233 prevents initiation of the viral polymerase complex at the promoter. AVG-233 binding site is present in the L 1-1749 fragment. AVG-233 has nanomolar activity against both RSV strains and clinical RSV isolates ( EC 50 =0.14-0.31 μM). AVG-233 can be used for research of respiratory syncytial virus ( RSV ) .