Inhibition of the replication of influenza A and B viruses by a nucleoside analogue (ribavirin).

A synthetic nucleoside analogue 1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboamide (ribavirin or RTCA) inhibits the replication of tissue culture of influenza B virus and also a wide range of influenza A viruses of human, animal and avian origin. The synthesis of influenza virus-induced antigens and also structural and non-structural polypeptides is inhibited by RTCA as detected by immunofluorescence and by pulse labelling experiments with [35S]-methionine. The inhibitory effects of RTCA on influenza A virus replication in tissue culture is reversed by a molar excess of guanosine or zanthosine which suggests that the compound acts at an early stage of virus RNA synthesis prior to the utilisation of the latter nucleosides. A possible inhibitory effect of RTCA on cellular DNA replication is not excluded.