The Nucleic Acid of Sendai Virus and Ribonucleic Acid Synthesis in Cells Infected by Sendai Virus

RNA was extracted from purified Sendal virus, labelled with ~P, and sedimented in sucrose density gradients. Under conditions of high ionic strength (o.t M-NaCI) the sedimentation coefficient was 57 S. In the presence of 0"005 M-EDTA, the sedimentation coefficient was reduced to 40 S, in-dicating that the RNA of the virus exists as a single-stranded molecule. The intracellular synthesis of virus-directed RNA during the latent period of infection of chick embryo cells by Sendai virus in the presence of actino-mycin was also studied. Cells were xtracted by the phenol + sodium dodecyl sulphate method at 2, 4, 6 and 7 hr after infection, having previously been ex-posed to [aH]uridine for at least 2 hr. It was found that the first newly formed RNA had a sedimentation coefficient of 18 S and could be detected between 2 and 4 hr after infection. From 4 hr onwards a 57 S component was found in increasing amounts until 7 hr after infection. Substantially similar results were obtained when infected cells were treated with detergent alone, and the mixture immediately centrifuged on density gradients except hat the prin-cipal RNA components now had sedimentation values of 57 S and 23 S