INHIBITORY EFFECT OF PYRIDOBENZAZOLES ON VIRUS-REPLICATION IN-VITRO

Twelve species of pyridobenzazoles and pyrimidobenzimidazole were exam ined as inhibitors of the replication of respiratory syncytial virus ( RSV) in HeLa cells. From the pyridobenzazoles studied, mido-4-cyano-1- oxo-1H,5H-pyrido[1,2-a]benzimidazol emerged as a potent inhibitor of t he RSV. Based on its inhibitory effect on the cytopathogenicity of the RSV in HeLa cells, the 50% effective dose was found to be 0.95 mu g/m l. The cytotoxicity of this compound for HeLa cells was examined by mo nitoring the incorporation of radiolabeled uridine into cellular RNA. The selectivity index was ca. 30, the same as Virazole.