- Volume 20, Issue 3, 1973
Volume 20, Issue 3, 1973
- Articles
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Isolation of Glucosamine from the Capsids of a Picornavirus
More LessSUMMARYThe purified capsids of echovirus 12 were found to contain radioactivity when radioactive glucosamine was provided for virus-infected cultures. Radioactivity was identified with glucosamine, after recovery from the virus particles by acid hydrolysis and paper chromatography. Although the label was not removable from the isolated virus particles without destruction of virus, polyacrylamide gel electrophoresis showed that it was not covalently bound to any of the four virus polypeptides since it migrated more rapidly and was identical electrophoretically to the glucosamine-labelled fraction isolated from uninfected cells. Glucosamine labelling of virus capsids was only achieved during virus multiplication, since labelled fractions from uninfected cells did not bind to virus capsids. Its apparently low mol. wt., lack of associated virus or cellular proteins, lack of labelling of virus with other radioactive sugars, and the similar electrophoretic migration of free N-acetyl glucosamine suggested that the component is an acetylated product that is trapped during the assembly of the virus.
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Genetic Complementation between Middle and Bottom Components of Two Strains of Radish Mosaic Virus
More LessSUMMARYKale virus (KV), turnip virus (HZ) and radish mosaic virus (RMV) are slightly related serologically to cowpea mosaic virus. Purified preparations comprize, top, middle and bottom components, of which only the last two contain nucleic acid. The nucleoprotein components of each virus were separated by centrifuging twice through a sucrose gradient in an MSE BXIV zonal rotor. Sometimes this was followed by centrifuging to equilibrium in a density gradient of rubidium bromide. Neither nucleoprotein component was infective alone, but infectivity was restored when each was mixed with the other component.
Mixtures in which the two components came from different viruses were infective only when they were made with KV and HZ. Serologically these two viruses are more closely related than either is to RMV. KV differed from HZ by two characters related to the coat protein. KV particles regularly formed aggregates of 12 particles and contained antigens that were not present in HZ. Single lesion isolates from mixtures of bottom component from one strain and middle component from the other did not form aggregates and lacked the antigens present in KV. Like cowpea mosaic virus, KV and HZ each have two coat proteins, and our results can be explained if each of the four virus components codes for a different coat protein. Therefore, the coat protein of the virus is coded by the nucleic acid of both middle and bottom components.
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Incomplete Virus Particles of Adenovirus Type 16
More LessSUMMARYHaemagglutinating populations of virus particles of adenovirus type 16 (I–VIII) were separated by isopycnic centrifuging in CsCl. One of these populations (V) contained complete virus particles. Fresh preparations of virus particles from all populations studied had a morphology indistinguishable from that of complete virus particles.
The five lightest populations were shown to contain [3H]-thymidine and to be infective; dose-response relationships indicated the occurrence of a multiplicity-dependent infectivity of the incomplete virus particles. SDS-polyacrylamide gel electrophoresis of incomplete virus particles of the lightest population demonstrated that they were deficient in three polypeptides, but contained three other polypeptides which were not detectable in complete particles. One characteristic polypeptide of incomplete particles and another characteristic polypeptide of complete particles displayed high ratios of arginine over threonine.
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The Interaction between Mycoplasma hominis and Poliovirus in Cell Culture
More LessSUMMARYEagle’s culture medium containing 2% heat-inactivated calf serum is inadequate for the growth of Mycoplasma hominis. However, when the medium was conditioned by remaining in contact with the monolayers for several days, or when it was supplemented with 10% mycoplasma medium, it supported the growth of this organism.
The presence of Mycoplasma hominis in MK and MS cell cultures had no effect on the replication of poliovirus type II, as judged by the titration of the infectivity of the virus produced. However, the presence of poliovirus in primary cultures of monkey kidney cells enhanced the growth of mycoplasma in such a way that the delay in the logarithmic phase of growth of this organism was overcome.
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Comparison of the Aerosol Stabilities of Foot-and-Mouth Disease Virus Suspended in Cell Culture Fluid or Natural Fluids
More LessSUMMARYA strain of foot-and-mouth disease (FMD) virus (O1 BFS 1860) held in aerosols at high relative humidity (r.h.) was more unstable when suspended in bovine salivary fluid than when suspended in cell culture fluid. This instability was due to the suspending medium rather than to the passage history of the virus and was not related to the high pH of the salivary fluid or to surface inactivation. The inactivation at high r.h. was caused by an undefined organic molecule which was dialysable and sensitive to heating at 70 °C but not at 60 °C.
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Energy Requirement for the Formation of Blender-resistant Complexes in Lactobacillus Phage Infection
More LessSUMMARYThe formation of blender-resistant complexes signifying the complete penetration of PL-1 phage genomes into the host cells, Lactobacillus casei atcc27092, was studied in a tris-maleate buffer using the technique of blending described by Hershey & Chase (1952). The process was not affected much by the age of the cells, but it was greatly inhibited when the cells had been previously starved. The process was dependent on the temperature, and therefore it was considered to be an energy-requiring process. Apparent activation energy (µ) was calculated to be about 8.3 kcal. The process which had been first inhibited at 0 °C was recovered at any time when the temperature was raised to 37 °C. Among the metabolic inhibitors tested, 10 mm-arsenate inhibited the process selectively without affecting either the infectivity of phage particles or the viability of the cells. On the contrary, cyanide, azide, arsenite, monofluoroacetate, dinitrophenol, pentachlorophenol, dicumarol, chloramphenicol and gramicidin S did not exhibit such a selective inhibition.
The significance of the active metabolism of the cells for the mechanism of phage genome penetration is discussed.
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Purification and Partial Characterization of Maize Dwarf Mosaic Virus Strain B (Sugarcane Mosaic Virus)
More LessSUMMARYMaize dwarf mosaic virus strain B was purified to apparent homogeneity. Virus protein migrated as a single component in polyacrylamide gels and had a mol. wt. of 36500 when estimated by sodium dodecyl sulphate gel electrophoresis but 28500 as determined by amino acid analyses. A total of 264 amino acid residues are present in the protein. The virus contains 6% RNA based on its phosphorus content (0.54 ± 0.07%) and the nucleotide composition of its nucleic acid (33.54% adenylic acid, 20.21% guanylic acid, 16.21% cytidylic acid, and 30.01% uridylic acid).
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Natural Selection of Mutants of Vesicular Stomatitis Virus by Cultured Cells of Drosophila melanogaster
More LessSUMMARYThe infection of cultured cells of the fruit fly Drosophila melanogaster (Schneider) with vesicular stomatitis virus (VSV) led to the establishment of persistent non-cytocidal infection. After weeks or months of persistent infection many VSV variants or mutants were detected all of which showed increased capacity for growth in these insect cells. We present a preliminary characterization of these viruses arising in the Drosophila cells.
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The Fragmentation of Cellular DNA and the Formation of Pseudovirions during SV 40 Infection of African Green Monkey Kidney Cells
More LessSUMMARYInfection of African green monkey kidney cells (AGMK) with simian virus 40 (SV40) results in a fragmentation of cellular DNA to a small mol. wt. form and the production of pseudovirions. The small mol. wt. cellular DNA was first detectable at about 45 to 60 h after infection and continued to increase in amount up to 105 h. Pseudovirions were preferentially formed at very late times also (60 to 96 h after infection).
Type 2 adenovirus does not cause cellular DNA fragmentation in infected AGMK cells and even prevents SV40 breakdown of cellular DNA in co-infected cells. DNA and protein synthesis were both required for the conversion of high mol. wt. cellular DNA to the smaller mol. wt. form. DNA replication was required up to 30 to 40 h after SV40 infection, while protein synthesis was required up to 48 to 60 h after infection for the efficient fragmentation of cellular DNA.
Extensive single-stranded breaks were detected in some 60 to 75% of the cellular DNA late in SV40 infection. Under these conditions some 20 to 45% of the double-straned cellular DNA was present in a low mol. wt. form. Preferential levels of highly repetitive sequences were not detected in the fragmented cellular DNA. It appears that this DNA represents a random collection of cellular DNA molecules with respect to the frequency of repetitive DNA sequences.
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Antigenically-related Viruses Associated with Infectious Bursal Disease
More LessSUMMARYBursae from chickens infected with infectious bursal disease have been examined by immune electron microscopy. Two types of virus particle have been detected, the larger being 55 to 60 nm in diam. and markedly hexagonal in outline, while the smaller has an appearance similar to that of the parvoviruses with a diam. of 18 to 22 nm. The presence of mixed aggregates and demonstrable antibody-bridging show that the two types of particle have at least one surface antigen in common.
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Isolation and Characterization of Virus-resistant Mouse Embryo Fibroblasts
More LessSUMMARYA method is described for the isolation of virus-resistant mutants of mammalian cells in culture. Cells of a mouse embryo fibroblast line (3T6) were treated with a mutagen and subjected to selection for virus resistance. The cells were infected with a temperature-sensitive mutant of Sindbis virus which was allowed to proceed through one cycle of replication at the permissive temperature. On transfer of the cells to the non-permissive temperature, further cycles of virus replication were prevented and non-infected cells allowed to grow out. Repetition of this procedure over 2 months resulted in the isolation of a population of 3T6 cells which resisted infection by Sindbis virus.
Single cell clones were isolated that were resistant to the growth of Sindbis virus and also to the growth of Mengo virus, Semliki Forest virus, vesicular stomatitis virus, Newcastle Disease virus, vaccinia virus and herpes simplex virus.
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Isopycnic Banding of Strains of Radish Mosaic Virus in Rubidium Bromide Solutions
More LessSUMMARYStrains KV and HZ of radish mosaic virus when centrifuged to equilibrium in caesium chloride gave four bands, although they have only two nucleoprotein components. However, when centrifuged to equilibrium in rubidium bromide, HZ gave only two major bands and KV gave these and several extra small bands, presumably because this strain contains aggregates of 12 particles derived from all 3 components and therefore having different densities from the nucleoprotein components.
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Concentration of Epstein-Barr Virus from Cell Culture Fluids with Polyethylene Glycol
More LessSUMMARYEpstein-Barr virus (EBV) is usually obtained from supernatant fluids of cultures of primate lymphoblastoid cells. The isolation of small amounts of virus particles from large vol. of culture fluid offers particular problems because of the osmotic fragility of herpes viruses, and attempts to concentrate biologically active EBV by zonal centrifuging in solutions containing sucrose have been unsuccessful. It is shown here that EBV particles can be conveniently concentrated from culture fluids with polyethylene glycol. The biological activity of the concentrated particles is retained, as measured by a superinfection assay, and good yields are obtained from supernatant fluids containing as little as 2 × 102 EBV particles/ml.
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Disruption of Herpes Virus Nucleocapsids using Lithium Iodide, Guanidine and Mercaptoethanol
More LessSUMMARYThe nature of the covalent and non-covalent bonds which are responsible for the maintenance of the morphological integrity of the herpes simplex virus type 1 nucleocapsid was examined. Virus particles were treated at various temperatures with mercaptoethanol, guanidine, or lithium iodide under neutral and alkaline conditions. After treatment with mercaptoethanol or lithium iodide, the virus particles morphologically resembled collapsed amorphous structures composed of loosely bound fibrous strands, which no longer retained the capsomeric detail. Subsequent exposure of these treated preparations to alkaline conditions or high concentrations of guanidine was required to break the bonds that held the strands together. It was not possible under the conditions employed in this study to selectively break the intercapsomeric bonds and thus release free intact capsomeres.
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Long Term Infection of Diploid African Green Monkey Brain Cells by Schwarz Measles Vaccine Virus
More LessSUMMARYA long-term infection of African green monkey brain (AGMBr) cells with Schwarz measles vaccine virus was established and maintained for 13 infected cell passages over 482 days. Results indicated that the majority of these cells contained latent, non-infectious virus and offered a useful tissue culture model for the study of measles virus in brain tissue. AGMBr cells infected with Edmonston ‘wild’ or SSPE-1 (an isolate from a patient with subacute sclerosing panencephalitis) could not be maintained beyond 2 passages.
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Adenovirus-induced Crystals: studies with Temperature-sensitive Mutants
More LessSUMMARYCells infected with temperature-sensitive mutants of adenovirus type 5 have been studied by electron microscopy. The results indicate a relationship between the formation of intranuclear crystals and the expression of adenovirus fibre antigen.
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Aggregates of Chloroplasts in Local Lesions induced in Chenopodium quinoa Wild. by Turnip Mosaic Virus
More LessSUMMARYAggregates of up to 20 chloroplasts occur in parenchyma cells from local lesions induced in Chenopodium quinoa Wild. by turnip mosaic virus. Electron microscopic examination revealed a single layer of virus particles parallel to the surface of chloroplasts between most of the aggregated chloroplasts.
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