Antiviral Action of Camptothecin
Abstract
Antiviral Action of Camptothecin 1 Susan B. Horwitz , Chung-Ke Chang and Arthur P. Grollman Departments of Pharmacology and Medicine, Albert Einstein College of Medicine, New York, New York 10461 Division of Biology, Department of Molecular Biology, Albert Einstein College of Medicine, New York, New York 10461 ABSTRACT At a concentration of 10 μ m , camptothecin inhibited vaccinia deoxyribonucleic acid (DNA) synthesis in HeLa cells. Inhibition of viral DNA synthesis was observed when the drug was added before infection or at 1 or 2 hr after infection. Inhibitory effects of camptothecin on vaccinia DNA synthesis could be reversed, even after exposure to the alkaloid for 2 hr. Viral DNA, isolated from vaccinia-infected, camptothecin-treated cells, displayed an altered sedimentation constant after alkaline sucrose density gradient centrifugation. Incorporation of uridine into vaccinia messenger ribonucleic acid was inhibited by camptothecin, but the activity of ribonucleic acid polymerase, as tested in isolated vaccinia cores, was not affected by the drug. Camptothecin had essentially no effect on replication of poliovirus in HeLa cells.