- Volume 4, Issue 2, 1969
Volume 4, Issue 2, 1969
- Articles
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Rod-shaped Pyocin 28
More LessSummaryPyocin 28 was obtained by induction of Pseudomonas aeruginosa p28 with mitomycin. Pyocin activity was correlated with the number of rod-shaped particles in purified preparations. The width of the pyocin rod was uniform, measuring about 90 Å, but the length was not uniform, varying from 200 to 4000 Å, but rods measuring 1000 to 1200 Å were most frequent. A dark central line and regular cross-striations were usually seen on the rod, and a fine fibre was sometimes visible at the sharp end. Pyocin activity was slightly reduced from ultrasonic treatment, but not at all by trypsin, Nagarse, DNase and RNase. The pyocin was stable between pH 5.0 and 8.0, and was completely inactivated by heating at 60° for 10 min. Specific attachment of numerous pyocin rods to the surface of sensitive bacteria was observed by the electron microscope.
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The Separation of Herpes Virus-specific Antigens by Polyacrylamide Gel Electrophoresis
More LessSummaryVirus-specific antigens in cells infected with herpes simplex virus were separated on a preparative scale by two-stage polyacrylamide-gel electrophoresis. In the first stage, termed ‘electrofiltration’, the extract was electrophoresed through 3.5% gel to remove larger aggregates. Antigens in the resulting filtrate were then separated in the second stage by electrophoresis through 7% gel. The protein was recovered by sectioning the gel followed by overnight elution. Recoveries of about 70% were obtained from a 12 to 15 mg. load. Immunodiffusion and analytical electrophoresis both confirmed that separation had been achieved.
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The Preparation of ‘Monoprecipitin’ Antisera to Herpes Virus Specific Antigens
D. H. Watson and P. WildySummaryInjection of single precipitin bands (from immunodiffusion tests) into the lymph nodes of rabbits produced antisera reacting in immunodiffusion tests with individual specific antigens of herpes simplex virus. Antisera were made to an antigen obtained by preparative electrophoresis of an extract of cells infected with herpes; neutralization of the infectivity of herpes virus was demonstrated. An antiserum was also prepared to the antigen common to extracts of cells infected with herpes and pseudorabies virus; it contained no neutralizing antibody.
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Effect of Ultraviolet Irradiation and Heating on the Interferon-inducing Capacity of Human Adenoviruses
More LessSummaryHeating adenovirus types 8 and 12 for 2 to 3 min. at 56° simultaneously reduced both interferon-inducting capacity and infectivity. In contrast, virus inactivated by u.v.-irradiation effectively stimulated interferon production in chick cells.
Chick cells infected with adenovirus type 12 and incubated at 25°, 35° or 40° produced about the same amount of interferon but the kinetics of interferon production differed, i.e. at the higher temperatures interferon formation commenced earlier.
The possibility that the penton antigen may be responsible for interferon induction by human adenoviruses in chick cells is discussed.
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Association of Pepper Ringspot Virus (Brazilian Tobacco Rattle Virus) and Host Cell Mitochondria
More LessSummaryExamination of thin sections of tissues from various plants infected with pepper ringspot virus showed the presence of characteristic aggregates of tubular particles, about 2000 Å long and 200 to 250 Å wide, considered to be pepper ringspot virus in situ. The pepper ringspot virus aggregates were associated with mitochondria in such a way that the virus particles were positioned perpendicularly on the surface of mitochondria. Aggregates of short (550 Å) particles were not found.
Except in xylem vessels, pepper ringspot virus aggregates were present in practically every type of tissue in infected plants, including the meristematic zone of shoot apex and root tip.
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The Morphogenesis of Simian Foamy Agents
More LessSummaryThe morphogenesis of a type 1 foamy agent (strain mk5) propagated in HEp2 cells was examined using ultrathin sections. The virus consisted of a nucleoid (350 Å) surrounded by two shells 600 Å and 900 Å in diameter. The inner shell and the nucleoid (together making a spherical internal component) appeared in the cytoplasm and by budding became enveloped by a morphologically altered cell membrane which bore projections. The staining properties of the virus depended on the method of fixation. Inclusions seen in infected cells are described. Strain mk5 was indistinguishable morphologically from a strain of type 2 foamy virus.
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The Binding of DNA Polymerase to Polyoma DNA
J. D. Pitts and M. FriedSummaryDNA polymerase from unpurified extracts of either infected or serumtreated resting mouse embryo cells was bound to double-stranded polyoma DNA and the complex could be separated from the free enzyme and other protein by zone centrifugation through sucrose gradients. Addition of extract to component I (supercoiled) polyoma DNA converted the DNA to a slower sedimenting form, but had little effect on the sedimentation rate of a mixture of components II and III. DNA extracted from the complex formed from extract and component I had properties indicating that both strands of the DNA were unbroken.
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Comparison of the Antiviral Activity in vitro of some Non-steroidal Anti-inflammatory Drugs
More LessSummaryIn cultures of mouse or chick embryo cells several non-steroidal anti-inflammatory drugs (salicylates, Ibufenac, phenylbutazone, Indomethacin, flufenamic and mefenamic acids, CI-583, and chloroquine) inhibit the multiplication of various viruses (encephalomyocarditis, Sindbis, influenza A2, Newcastle disease, herpes simplex and vaccinia). Two factors were critical for the virus inhibitory action of these drugs: the concentration of serum and the pH of the medium. The antiviral effect of these drugs seems to be due mainly to limitation of intracellular synthesis. However, salicylates and anthranilates also inhibit the adsorption and/or penetration of encephalomyocarditis virus into mouse cells.
The antiviral potency shows some correlation with other biochemical, cellular and clinical activities of these drugs.
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Induction of an Arginine-rich Component during Infection with Influenza Virus
More LessSummarySecondary chick embryo fibroblasts infected with fowl plague virus were pulsed with [3H]arginine and treated with ethanol and hydrochloric acid. Radioautographic pictures disclosed heavily labelled nuclei in infected cells; uninfected controls had an even distribution of grains over nucleus and cytoplasm. Total incorporation into infected cells was about three times that in controls during the whole productive cycle. Quantitative comparison of the number of grains over nucleus and cytoplasm indicated that the nucleus was the site of synthesis of this arginine-rich component. With [3H]leucine and [3H]lysine additional nuclear incorporation was very weak or could not be seen.
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Infectivity and Capacity for DNA Replication of Vaccinia Virus Irradiated by γ-Rays
More LessSummaryPurified vaccinia virus was irradiated by γ-rays under direct-effect conditions. The ability of the irradiated samples to form plaques (infectivity) and to induce viral DNA synthesis was determined. The radiosensitive volume of the viral unit causing infection (1.9 × 10−17 cm.3) is very small compared with the volume of the whole viral DNA (∼ 10%).
The inactivation of the DNA replication function follows a simple exponential law. The radiosensitive volume necessary for the replication of DNA (1.6 × 10−18 cm.3) represents only 8.5% of the DNA necessary for infectivity and 0.85% of the total viral DNA. This indicates existence of a dissociation between two functions of vaccinia virus, the synthesis of viral DNA and infectivity.
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Freeze-etching Observations on Tobacco Leaves Infected with Tobacco Mosaic Virus
More LessSUMMARYTobacco leaf mesophyll cells infected with tobacco mosaic virus were freeze-etched. Virus particles frequently fractured during the freeze-etching process and the implications of this observation are discussed. Freeze-etching is useful in investigations of the fine structure of virus-infected leaf cells and the general application of freeze-etching as an ancillary preparative technique to that of thin sectioning for the study of virus-infected cells is outlined.
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Stimulation of Biosynthesis of Tobacco Mosaic Virus by Antimetabolites
More LessSummaryTobacco leaf discs were treated with different concentrations of actinomycin C, dl-parafluorphenylalanine, 8-azaguanine, chloramphenicol and puromycin-dihydrochloride before, simultaneously and after inoculation with tobacco mosaic virus. The treatment with low concentrations of antimetabolite simultaneously with tobacco mosaic virus inoculation stimulated the tobacco mosaic virus biosynthesis up to ninefold, whereas higher concentrations caused a ten- to 1000-fold inhibition. The stimulatory effect of pretreatment suggests the presence of a factor or factors with antiviral properties present in plant tissue becoming activated upon virus infection. The lack of an effect of treatment with antimetabolites ½ to 30 hr after inoculation indicates that activation of such factor(s) must occur within the first 30 min. after infection of tobacco leaf cells with tobacco mosaic virus.
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Degradation of Cellular Ribonucleic Acid in Newcastle Disease Virus Infected Cells
More LessSummaryFollowing Newcastle disease virus infection, the synthesis of both cellular RNA and DNA in chick embryo fibroblast monolayers was inhibited. In such monolayers, Newcastle disease virus infection did not significantly reduce the content of cellular DNA within 10 hr, but did reduce the amount of cellular RNA by about 50% in that time. A part of the RNA was degraded into acid-soluble material and leaked out of the cells. Some fraction of the ribosomal RNA gave rise to small molecular weight fragments which sedimented near the transfer RNA region as determined by sucrose density gradient centrifugation. Evidence is presented indicating that virus-induced proteins, which were synthesized by 6 hr after infection, were involved in the RNA degradation process.
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Protein Components of a Mycobacteriophage
More LessSummaryThe protein components of a mycobacteriophage were dissociated with various concentrations of KOH. The tails disintegrated at concentrations leaving the heads intact. The process of disintegration of the heads was gradual and increased when the normality of the potassium hydroxide was augmented. Following dialysis of this alkaline degraded material against distilled water at +4° and adjustment of pH to 5 a reaggregation of protein fragments very similar to tails was observed. This also occurred before disintegration of the heads. The alkaline-degraded material was studied by immunodiffusion before and after dialysis; the ability to precipitate with antibodies was lost after treatment with strong KOH but was recovered after dialysis.
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Biological Markers for Differentiation of Herpes-virus Strains of Oral and Genital Origin
More LessSummaryHerpes simplex virus from mouth and genitalia could be distinguished antigenically and also differed in certain biological properties. Viruses isolated from oral lesions replicated better in rabbit kidney cell cultures than did viruses isolated from genital lesions; however, the total number of virus particles produced was the same for both virus types. A greater proportion of particles in stocks of the oral strains grown in rabbit kidney cells were enveloped than in stocks of genital strains grown in the same cells. The genital strains formed plaques in chick embryo cell cultures, but the oral ones did not and replicated poorly. The genital strains were more neurovirulent when injected intracranially into mice than were the oral strains, based on the number of p.f.u. injected; however, there was no difference in neurovirulence if the doses were calculated in terms of total particles injected. These differences provide useful markers for characterizing the types of herpes virus.
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Single-stranded DNA from the Kilham Rat Virus
More LessSummaryThe nucleic acid of the Kilham rat virus was found to be single-stranded DNA. This was demonstrated by the lack of a distinct melting curve of the viral DNA, lack of reaction of actinomycin D with viral DNA, and the reaction of both intact virus and viral DNA with formaldehyde. The hydroxymethyl groups, added by the formaldehyde, did not interfere with complete recovery of the secondary structure of the extracted DNA.
Electron micrographs of the DNA also showed pooling and sharp folds and turns which are characteristics of single-stranded DNA.
When rat virus was centrifuged to equilibrium in caesium chloride density gradients, three peaks of haemagglutinating activity were found at densities of 1.43, 1.38 and 1.32 g./cm.3. The examination of material from these peaks showed the peak at 1.43 g./cm.3 contained full viral particles, the peak at 1.38 g./cm.3 contained a mixture of full and empty viral particles, and the peak at 1.32 g./cm.3 contained large amounts of debris in which an occasional viral particle was visible. It was concluded from these data that the intact viral particle had a density of 1.43 g./cm.3, and the protein coat had a density of 1.32 g./cm.3. The density of the DNA was found to be 1.72 g./cm.3; therefore, the intact viral particle contained 34% DNA.
The average length of the DNA molecule extracted from the rat virus was found to be 1.30 µm., which gave a molecular weight of 1.2 × 106 for the DNA. With this value and the 34% value found for the DNA content of the viral particle, the molecular weight of the virus particle was estimated to be 3.6 × 106.
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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)