TRANSPORT OF VIRAL RNA IN KB CELLS INFECTED WITH ADENOVIRUS TYPE 2 |
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| Authors: | Heschel J. Raskas and Case K. Okubo |
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| Affiliation: | From the Institute for Molecular Virology and the Department of Pathology, Saint Louis University School of Medicine, Saint Louis, Missouri 63104 |
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| Abstract: | Messenger RNA transport was studied in KB cells infected with the nuclear DNA virus adenovirus type 2. Addition of 0.04 µg/ml of actinomycin completes the inhibition of ribosome synthesis normally observed late after infection and apparently does not alter the pattern of viral RNA synthesis: Hybridization-inhibition experiments indicate that similar viral RNA sequences are transcribed in cells treated or untreated with actinomycin. The polysomal RNA synthesized during a 2 hr labeling period in the presence of actinomycin is at least 60% viral specific. Viral messenger RNA transport can occur in the absence of ribosome synthesis. When uridine-3H is added to a late-infected culture pretreated with actinomycin, viral RNA appears in the cytoplasm at 10 min, but the polysomes do not receive viral RNA-3H until 30 min have elapsed. Only 25% of the cytoplasmic viral RNA is in polyribosomes even when infected cells have been labeled for 150 min. The nonpolysomal viral RNA in cytoplasmic extracts sediments as a broad distribution from 10S to 80S and does not include a peak cosedimenting with 45S ribosome subunits. The newly formed messenger RNA that is ribosome associated is not equally distributed among the ribosomes; by comparison to polyribosomes, 74S ribosomes are deficient at least fivefold in receipt of new messenger RNA molecules. |
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