ANTIVIRAL ACTIVITIES OF 5-ETHYNYL-1-BETA-D-RIBOFURANOSYLIMIDAZOLE-4-CARBOXAMIDE AND RELATED-COMPOUNDS

A series of novel compounds, 5-alkynyl-1-beta-D-ribofuranosylimidazole-4-carboxamides, have been identified as broad-spectrum antiviral agents. 5-Ethynyl-1-beta-D-ribofuranosylimidazole-4-carboxamide (EICAR), the most potent congener of the group, showed antiviral potency about 10- to 100-fold greater than that of ribavirin. Similar in spectrum to ribavirin, EICAR was particularly active (50% inhibitory concentration, 0.2 to 4-mu-g/ml) against poxviruses (vaccinia virus), togaviruses (Sindbis and Semliki forest viruses), arenaviruses (Junin and Tacaribe viruses), reoviruses (reovirus type 1), orthomyxoviruses (influenza A and B viruses), and paramyxoviruses (parainfluenza virus type 3, measles virus, subacute sclerosing panencephalitis virus, and respiratory syncytial virus). EICAR was also cytostatic for rapidly growing cells (50% inhibitory concentration, 0.2 to 0.9-mu-g/ml). EICAR inhibited vaccinia virus tail lesion formation at doses that were not toxic to the host. EICAR is a candidate antiviral drug for the treatment of pox-, toga-, arena-, reo-, orthomyxo-, and paramyxovirus infections.