This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Kakefuda, T. Articles by Kitano, Y. Search for Related Content PubMed PubMed Citation Articles by Kakefuda, T. Articles by Kitano, Y.

Reverse Transcription of the Viral Genome Associated with the Plasma Membrane after Infection with RNA Tumor Viruses

Chemistry Branch, National Cancer Institute, NIH, Bethesda, Maryland 20014 [T. K., C. W. D., T. M. B., Y. K.], and Flow Laboratories, Inc., Rockville, Maryland 20852 [M. H.]

Electron microscopic autoradiography of 3T3/BALB and chicken embryo cells infected with murine sarcoma virus or Rous sarcoma virus (RSV) showed thymidine-³H incorporation in the region of the plasma membrane beginning 1 hr after infection. The photopositive grains dispersed diffusely in the cytoplasm as the postinfection time was prolonged. Reverse transcriptase activity generated by virus infection was assayed for by incubating isolated cell organelles in a transcription mixture with labeled deoxythymidine 5'-triphosphate. The DNA products were hybridized with viral RNA and then alayzed by isopycnic centrifugation in Cs₂SO₄ to determine whether any sequence homology existed. The plasma membrane showed the highest activity. DNA hybridizable to viral RNA was also isolated from the plasma membrane fraction of RSV-infected cells. These results indicated that the initial DNA copy of viral RNA is synthesized at the plasma membrane about 1 hr after infection and this synthesis continued for up to 7 to 10 hr. The DNA synthesized in vitro with isolated plasma membranes was found to consist of small homogeneous fragments having a molecular weight of about 1.5 x 10⁵. In contrast, the virus-specific DNA synthesized in the living cells and extracted from the plasma membrane of RSV-infected chicken embryo cells was heterogeneous in size ranging from 10⁵ to higher than 10⁶ daltons. No evidence was found for virus-specific, reverse transcription associated with plasma membranes in uninfected cells. Neither microsomes, ribosomes, nor mitochondria were found to be involved in the initial transcription of viral RNA a short time after infection.

Received 4/ 9/73. Accepted 11/30/73.