Selective Inhibition of Vaccinia Virus by the Antibiotic Rifampicin

RIFAMPICI 1 , a semi-synthetic derivative of rifamycin 2 which was isolated from Streptomyces mediterraneus , is a clinically useful, orally active antibiotic 3–5 . It inhibits bacterial RNA synthesis in vivo 6,7 and in vitro 8–11 by interacting directly with the DNA-dependent RNA polymerase 8,11 . While rifampicin inhibits bacterial RNA polymerase, it does not affect in vitro the activity of mammalian RNA polymerase 9,10 .