- Volume 7, Issue 1, 1970
Volume 7, Issue 1, 1970
- Articles
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Replication of Foot-and-Mouth Disease Virus Ribonucleic Acid
T. F. Wild and F. BrownSUMMARYThe effect of heat and formaldehyde on the sedimentation properties of virus RNA and the RNA induced in baby hamster kidney cells by infection with foot-and-mouth disease virus has been studied. The sedimentation rate of the induced 37s RNA was reduced considerably by treating with 6% formaldehyde in 0·01 m-EDTA at 37° but it still sedimented faster than the 35s RNA extracted from purified virus which had been treated similarly. Part of the interjacent RNA sedimented at the same rate as the 35s virus RNA after similar treatment. The sedimentation rate of the 16s ribonuclease-resistant RNA was unaffected. After treating with formaldehyde at 70°, part of the ribonuclease-resistant RNA sedimented faster than virus RNA which had received similar treatment. These results show that the greater rate of sedimentation of the 37s RNA is caused by the larger size of the induced RNA compared with the 35 s virus RNA and suggest that the more rapid sedimentation of the ribonuclease-resistant RNA after denaturing at 70° may be due to its existence as a circular molecule.
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The Multiplication of Measles Virus in Human Amnion Cells in vitro
More LessSUMMARYThe multiplication of the edmonston strain of measles virus in suspensions of human amnion cells was studied. The first new virus appeared in the cytoplasmic fraction of the cells 17 to 20 hr after infection. After another 7 hr the virus was liberated into the medium. The multiplication of the virus was not inhibited by actinomycin D as measured by virus growth, virus plaque formation, or change in sensitivity to u.v.-irradiation. The u.v.-irradiation of monolayers before infection did not reduce plaque formation.
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Dissection of Vesicular Stomatitis Virus into the Infective Ribonucleoprotein and Immunizing Components
More LessSUMMARYTreatment of the infective component of vesicular stomatitis virus with Nonidet P40 produces an infective skeleton-like structure which has the shape and approximate size of the intact virus particle. The infectivity of the skeleton is enhanced 100 to 1000 fold by mixing with DEAE-dextran. The skeleton lacks the outer envelope and fringe structure and in consequence does not produce neutralizing antibodies in guinea pigs. The density of the skeleton is 1·22 g./ml. in potassium tartrate gradients compared with 1·14 g./ml. for the virus. Sodium deoxycholate removes protein from the skeleton and releases the filamentous ribonucleoprotein in an infective form. As with the skeleton, the infectivity of the ribonucleoprotein is enhanced by DEAE-dextran. Ribonuclease has no effect on the ribonucleoprotein but trypsin destroys its infectivity. The ribonucleoprotein has a density of 1·22 g./ml. in tartrate gradients, sediments at about 140 s in sucrose gradients and does not produce neutralizing antibodies in guinea-pigs.
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Investigations on Virus Production in RSV Mammalian Tumours
More LessSUMMARYSix different Rous mammalian tumour lines were studied for the occurrence of virus specific antigens, the presence of the viral genome and the synthesis of infectious and non-infectious particles. Four Rous tumour lines were induced in stumice presumably free from latent murine leukemia virus (MLV), three of them by a cloned Schmidt-Ruppin strain of Rous sarcoma virus (sr-RSV) belonging to sub-group D, the fourth with an uncloned sr-RSV strain. In addition a Prague(P)-RSV induced mouse tumour line (RVP3) and an sr-RSV induced hamster tumour line (RSH) and sr-RSV induced chicken tumours were likewise investigated. In all mammalian lines, except for RVP3, avian leukosis group specific complementfixing antigen was found. Tumour specific transplantation antigen was demonstrated in all mammalian lines except RSH, whereas no infectious RSV could be detected in any of the mammalian tumours. Likewise electron microscopy revealed no virus particles in more than 9500 cell sections of RSV-stu tumours, but the viral genome was shown to be present by transfer of the tumour to chickens. In the RVP3 line virus particles were detected resembling typical murine leukemia virus while in the RSH line particles were found morphologically similar to the latent hamster virus described by Bernhard & Tournier (1964).
The interpretation and significance of the findings are discussed.
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Inclusion Bodies and Tubular Structures in Chenopodium amaranticolor Plants Infected with Strawberry Latent Ringspot Virus
More LessSUMMARYThe first change observed in cells of leaves systemically infected with strawberry latent ringspot virus was the formation of inclusion bodies near the nucleus. The inclusions were largely composed of endoplasmic reticulum, complex membranous structures and ribosomes. Three days later their outer parts contained unbranched, double-walled, slightly flexuous tubules about 50 nm. wide and up to at least 2·5 μm long. Each tubule, or occasionally two or three tubules, was enclosed in a membranous sheath 80 to 120 nm. in diameter, joined to the endoplasmic reticulum. The tubules contained a single row of up to 100 or more darkly stained virus-like particles. Some tubules ended within the inclusion and some at plasmodesmata, in which virus-like particles occurred. The central, predominantly membranous, regions of the inclusions contained masses of faintly stained, apparently hollow structures resembling empty shells of virus coat protein.
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Inhibition of Infectious Bovine Rhinotracheitis Virus Multiplication by Thiosemicarbazones
More LessSUMMARYThe addition of either isatin-β-thiosemicarbazone (IBT) or its N-methyl derivative effectively inhibited the multiplication of various isolates of infectious bovine rhinotracheitis virus. Treatment of infected cultures with IBT early or late in the log. phase of replication markedly suppressed the production of infectious virus, indicating that the drug inhibits virus maturation. The time course of formation of infectious virus and of synthesis of viral DNA and viral protein was determined with the inhibitors FUdR and cycloheximide, respectively. In radioisotope experiments, IBT inhibited the incorporation of label into both RNA and DNA at a fairly early stage of the virus growth cycle.
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Volume 7 (1970)
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Volume 6 (1970)
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Volume 5 (1969)
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Volume 4 (1969)
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Volume 3 (1968)
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Volume 2 (1968)
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Volume 1 (1967)