Interferon Induction by Viruses and Polynucleotides: A Differential Effect of Camptothecin

Summary The plant alkaloid camptothecin inhibits interferon production induced by Newcastle disease virus (NDV) or ultraviolet-irradiated NDV in chick and human cells, and by Sindbis virus in chick cells. It has no effect on interferon production induced by poly(rI).poly(rC) in chick and human cells. No effect of camptothecin could be detected on the multiplication of NDV, and it is concluded that the inhibition reflects a difference between interferon induction by viruses and by polynucleotides.