Inhibition of Interferon Action by Cytochalasin B, Colchicine, and Vinblastine

Cytochalasin B, colchicine, and vinblastine decrease the antiviral effect of interferon when added to cells simultaneously with interferon. The drugs are effective alone but their potency increases when used in combination. The lack of development of the antiviral state is observed without any detectable modifications in cellular RNA or protein synthesis. These drugs are known to disrupt microtubules and microfil-aments which are therefore probably necessary for interferon action. They could be involved in the distribution of membrane-associated receptors and/or in interactions between receptors and the cytoplasma. The initial steps leading to the establishment of antiviral protection by interferon could depend on these mechanisms.