1887

Journal of General Virology header logo - Volume 46, Issue 1, 1980

Volume 46, Issue 1

Volume 46, Issue 1, 1980

  • Animal

      • Production and Initial Characterization of Rat Interferon

        https://doi.org/10.1099/0022-1317-46-1-243
        SUMMARY

        Rat interferon of relatively high specific activity (about 10 units/mg protein) was produced in embryonic rat cells treated with Newcastle disease virus at a high m.o.i. The cells were cultured in serum-free medium and the interferon was precipitated and concentrated with 0.02 -zinc acetate or with ammonium sulphate at 85% saturation. With both methods the increase in interferon activity was greater than the concentration factor. The rat interferon activity was stable on treatment with 0.15 -perchloric acid or three cycles of freezing and thawing, but incubation at 37 °C for 1 h resulted in a 50% loss in activity. It had no cross activity in human or mouse cells. The sensitivity of different types of rat cells for rat interferon differed widely and was dependent on the challenge virus. Human interferons had no detectable antiviral activity on rat cells and did not block the activity of rat interferon.

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  • Plant

      • Tobacco Mosaic Virus Infection Does Not Alter the Polyadenylated Messenger RNA Content of Tobacco Leaves

        https://doi.org/10.1099/0022-1317-46-1-139
        SUMMARY

        Measurements of incorporation of H-histidine into proteins in discs from tobacco mosaic virus-infected leaves suggest that the rate of host protein synthesis is reduced by up to 75% during virus multiplication but then recovers. Polyadenylated messenger RNAs from healthy and virus-infected plants were found to have similar size distributions and polyadenylic acid chains of similar lengths. Tobacco mosaic virus infection did not cause any alteration in the concentration of host polyadenylated messenger RNA. This makes it unlikely that rates of transcription or turnover of host polyadenylated messenger RNA were altered by infection. It is suggested that inhibition of host protein synthesis during virus multiplication may result from controls at the translational level, possibly by competition between the messenger RNAs for virus and host proteins.

    • Viroid-like Properties of an RNA Species Associated with the Sunblotch Disease of Avocados

      https://doi.org/10.1099/0022-1317-46-1-157
      SUMMARY

      A low mol. wt. RNA species is associated with sunblotch disease of avocados. The RNA (SB-RNA) was recovered from leaves and bark of symptomless carrier trees and from bark lesions of symptom-bearing trees. It was not detected in leaves or bark from lesion-free areas of symptom-bearing trees or in leaf or bark from healthy trees.

      SB-RNA is soluble in LiCl and migrates in 20% polyacrylamide gels. In high salt buffers, it is resistant to ribonuclease A at a concentration of 1 µg/ml and is degraded only slowly at 10 µg/ml. The RNA is less resistant to ribonuclease A at low salt concentrations (0.01 ). The mobility of the SB-RNA in polyacrylamide gels is not affected by heat denaturation. The apparent mol. wt. of native SB-RNA is 65000 whilst under denaturing conditions it is 112000 to 115000.

      SB-RNA occurs in high concentration in leaves of symptomless carrier trees being detected in 1 g of fresh leaf. In tissue fractionation experiments, SB-RNA was associated mainly with the chloroplast and endoplasmic reticulum fractions. It is concluded from these properties of SB-RNA that sunblotch is a viroid disease.

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