- Volume 1, Issue 1, 1967
Volume 1, Issue 1, 1967
- Articles
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Immunofluorescence of Abortive and Complete Infections by Influenza A Virus in Hamster BHK21 cells and Mouse L cells
More LessSummaryThe synthesis and transport of the soluble antigen of influenza A virus were traced by immunofluorescent staining with human convalescent sera during abortive and complete infection of hamster BHK21 cells and mouse L cells. Times of synthesis in the nucleus, transport to the cytoplasm and extrusion by the cell were the same in complete and in abortive infection.
The product of abortive infection contained soluble antigen, went through the same stages of adsorption, penetration and disposal as infectious virus but differed from it in being non-infectious, non-interfering and in not producing phenotypic mixing. These deficiencies suggest that RNA is either absent from or fails to function in abortive virus.
Ring-like structures were detected in the nucleus at late stages in the synthetic cycle. Their antigenic nature was not ascertained but in L cells soluble antigen appeared first round a nucleolar halo.
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Morphological Characteristics of Three New Actinophages
More LessSummaryThree newly isolated strains of Streptomyces phages have been examined by electron microscopy using the negative-staining technique. These phages have polyhedral heads and noncontractile tails ending in a clearly distinct fixation structure. They differ in their dimensions, head outline, flexibility of the tail and type of fixation plate. Some of their characteristics are new in the group of actinophages but correspond to known structures in other phage groups.
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A Study of Rabbit Kidney Vacuolating Virus and its DNA
More LessSummaryRabbit kidney vacuolating virus is similar to polyoma virus in the size and structure of the virus particle. The DNA of the virus is also similar to the DNA of polyoma virus, being supercoiled and circular with a molecular weight of approximately 3 million. The base composition of the DNA, 43 % guanine plus cytosine (GC), is intermediate between that of polyoma virus DNA, 48 % GC, and that of simian virus 40 DNA, 41 % GC. It is concluded that rabbit kidney vacuolating virus should be placed with polyoma virus and simian virus 40 as a member of the polyoma group of viruses.
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The Effect of Interferon on the Synthesis of RNA in Chick Cells Infected with Semliki Forest Virus
More LessSummaryWhen cells were pretreated with amounts of interferon which caused a 92 to 99 % reduction in virus production, the yields of infectious RNA were inhibited by 67 to 81 %, while the rate of incorporation of [3H]adenosine into total virus specific RNA was inhibited by only 48 to 65 %. Sucrose gradient analysis of the virus specific RNA synthesized in untreated infected cells showed it to consist of (i) 45 S infectious RNA which is probably the RNA of the mature virus, (ii) 26 S ribonuclease-sensitive RNA, possessing not more than 3 % of the infectivity of 45 S RNA, whose function is not known, but which is the major component early in infection, and (iii) 20 S ribo- nuclease-resistant RNA, which is probably a double-stranded replicative form. The inhibition by interferon of the synthetic rates of these three RNA species was not uniform. 45 S RNA showed the same sensitivity to interferon as did infectious RNA. The synthesis of 20 S ribonuclease-resistant RNA and of 26 S ribonuclease-sensitive RNA were relatively resistant to interferon action.
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The Effect of Interferon on the Synthesis and Activity of an RNA Polymerase Isolated from Chick Cells Infected with Semliki Forest Virus
More LessSummaryThe effect of interferon on the activity and synthesis of a specific Semliki forest virus RNA polymerase has been studied. Highly purified and semi- purified interferons were without effect on the action of the viral RNA polymerase in the in vitro assay, while crude interferon preparations were inhibitory. Polymerase activity was low in interferon-treated infected cells, but this did not result from the presence of enzyme inhibitors in the preparations. Attempts to demonstrate an inhibitor of the polymerase in interferon-treated uninfected cells were unsuccessful. The inhibition of viral RNA synthesis observed in interferon-treated cells may result from an inhibition of the synthesis of the viral RNA polymerase rather than from an inhibition of the action of this enzyme.
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A Chromatographic Procedure for the Purification of Influenza Virus
More LessSummaryOwing to the difficulties of achieving consistently good recoveries of virus from allantoic fluid containing influenza virus by chromatography on calcium phosphate columns the factors determining optimum yield were systematically investigated. It was found that calcium phosphate prepared by precipitation at a controlled pH of 7·5 gave best results provided that eluting buffers were adjusted to the same pH. Although calcium phosphate fractions were still evidently contaminated with non-viral material, further purification could be obtained by chromatography in agarose-gel columns. It appeared that separation of the virus on these columns was probably achieved as a result of the binding of virus surface groups on to the gel. A minimum overall purification factor of about 800-fold was achieved.
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Apparent Symbiotic Interaction Between Particles of Tobacco Rattle Virus
More LessSummarySUMMARY
The predominant lengths of tubular particles produced by the CAM isolate of tobacco rattle virus (520 and 1950 A long) and of the PRN isolate (650 to 800 and 1900 A long) were separated by density gradient centrifugation. On their own, short particles of each isolate neither caused lesions in Chenopodium amaranticolor leaves nor multiplied detectably. Long particles of either isolate caused lesions which contained virus nucleic acid, but virus particles were not found in extracts of the lesions; when the lesions were thawed after 3 days storage at −15°, the extracts had little or no infectivity. When short particles were mixed with long particles of the same isolate, the number of lesions produced by the long particles was not affected, but a proportion of these lesions then contained tubular virus particles of both lengths, and also infective material resistant to freezing and thawing. This proportion increased from zero to unity with increasing concentration of short particles in the inoculum; it also increased with increasing susceptibility to infection of the plants used as the source of the lesions, but seemed unaffected by the concentration of long particles in the inoculum. With isolate CAM, the lesions containing stable virus particles could be distinguished by their smaller necrotic centres. When short particles were ultraviolet-irradiated, their ability to interact with long ones was abolished, but the interaction was not prevented by removing virus protein from both long and short particles by phenol treatment. No interaction was detected between particles of the two different isolates, which are distantly related serologically, or between their nucleic acids. Each isolate of tobacco rattle virus seems to be a system of two or more pieces of infective nucleic acid interacting specifically in a symbiotic manner.
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Comparative Growth and Selection of Small Plaque and Large Plaque Encephalomyocarditis Virus in the Absence of Inhibitors from Agar
More LessSummaryDuring multicycle growth of clones of encephalomyocarditis (EMC) virus forming large plaques (EMC/r), small-plaque-forming virus (EMC/r+) appeared and was always selected by conditions in the growth medium to become the predominant plaque type. EMC/r arose but was never selected by conditions in the growth medium to predominance in virus pools initiated by EMC/r+ virus clones. Comparison of virus growth showed that EMC/r+ was produced and released from EMC/r+ infected L cells earlier and in 3- to 5-fold higher yields than was EMC/r from L cells infected with EMC/r. Thus, when separately infected cells are considered, selection strongly favoured EMC/r+ progeny.
In mixed infection of L cells with EMC/r+ and EMC/r, it was shown that:
- (1) Selection favouring the EMC/r+ virus was reduced as the exposed multiplicity/cell of EMC/r+ virus increased from 0·01 to 5·0 p.f.u./cell.
- (2) At 1·0 p.f.u./cell EMC/r and 5·0 p.f.u./cell of EMC/r+ less virus of both types was formed in 8 hr than in controls with each virus alone at the same multiplicity.
- (3) Eight hr after infection more EMC/r was produced and/or released at 0·01 or 0·1 p.f.u./cell EMC/r and 1·0 or 5·0 p.f.u./cell of EMC/r+, than in control cultures without EMC/r+ virus.
‘ Pure ’ ( > 99 %) pools of the EMC/r virus strain containing 109 to 1010 p.f.u. were produced consistently by increasing the EMC/r virus pool by growth in consecutive single cycle steps, thus eliminating the selective conditions of multicycle growth.
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The Mutability of Small-Plaque-Forming Encephalomyocarditis Virus
More LessSummarySixty-four single plaque subclones of a small-plaque-forming mutant of encephalomyocarditis virus, EMC/r+, were isolated and titrated. In addition to EMC/r+ virus, some contained large-plaque-forming virus, EMC/r. The selective conditions which prevailed during the growth and isolation of the subclones were analysed in detail. All the evidence suggests that only negligible differential selection favouring either the parental (EMC/r+) or the newly arisen plaque type (EMC/r) could have taken place. The changing selective conditions which operate during the growth of EMC/r mutants arising during the plaque assay of EMC/r+, and which slow down their emergence, are discussed. The changes in plaque morphology were shown to be genetically determined. For estimation of the mutation rate the subclones were placed a priori into one of three groups according to their total virus (infectivity) content. The mutation rate from r+ → r was calculated by four methods from each of the 3 groups and found to be 1–2 × 10−1 per particle per duplication.
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The Effects of substituted Benzimidazoles on the Growth of Viruses and the Nucleic Acid Metabolism of Host Cells
More LessSummaryThe antiviral effects of three substituted benzimidazoles, 4,5,6,trichloro- l-β-D-ribofuranosyl benzimidazole, 2-mercapto-1 -(β-4-pyridethyl) benzimidazole and 2-(α-hydroxybenzyl) benzimidazone, have been investigated and compared with their effects on the RNA metabolism of the host cells.
4,5,6,trichloro-l-β-D-ribofuranosyl benzimidazole and 2-mercapto-l-(β-4- pyridethyl) benzimidazole inhibit the growth of influenza A and parainfluenza 1 in calf kidney cells, and vaccinia in L cells, but they also reduce the synthesis of cellular RNA proportionately. They inhibit the growth of EMC in L cells, but only at concentrations at which host cell RNA synthesis is very much reduced. Their action is therefore not specific to a virus induced process.
In contrast, 2-(α-hydroxybenzyl) benzimidazole suppresses the growth of encephalomyocarditis virus in L cells at concentrations which have little effect on host cell RNA synthesis.
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Nearest Neighbour Base Sequence Analysis of the Deoxyribonucleic Acids of a Further Three Mammalian Viruses: Simian Virus 40, Human Papilloma Virus and Adenovirus Type 2
More LessSummaryThe nearest neighbour frequency analyses of the DNAs of Simian virus 40, human papilloma virus and adenovirus type 2 are reported. The two small oncogenic viruses have DNA closely resembling that of the host cells, which confirms and extends the previous findings for such viruses. The DNA of adenovirus type 2 shows only limited resemblance to that of the host cells. The experimental findings are discussed in the context of previous analyses of the DNAs of polyoma virus, Shope papilloma virus, herpes simplex virus, pseudorabies virus, equine rhinopneumonitis virus and vaccinia virus.
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Water as a Factor in the Photoinactivation of Vaccinia Virus
More LessSummaryHigh concentrations of glycerol and glucose decreased the rate of photoinactivation of vaccinia virus by methylene blue. These results could not be attributed to changes in the viscosity of the medium or to the impairment of the initial dye sensitization of the virus. Inhibition of photoinactivation by glycerol was not wholly dependent on O2 concentration. Lyophilization of dye-sensitized virus prevented its subsequent inactivation by exposure to light. These results are interpreted as indicating that water is involved in the photoinactivation process, although its role is as yet obscure.
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DNA Synthesis in Scrapie-Affected Mouse Brain
More LessSummaryDuring the later stages of the development of scrapie, an enhanced synthesis of DNA is detectable in the brains of affected mice. The synthesized DNA is largely confined to the nuclear fraction of the cell whereas the agent is mainly associated with mitochondria. There is evidence that the synthesis of the scrapie-associated DNA can be depressed in vivo in the presence of some specific inhibitors of DNA synthesis. An unsuccessful attempt was made to interfere with the normal development of scrapie by the repeated injection of inhibitors throughout the incubation period of the disease. It seems that the synthesis of DNA is not primarily involved in the development of the disease.
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Volumes and issues
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Volume 105 (2024)
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Volume 102 (2021)
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Volume 50 (1980)
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Volume 36 (1977)
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Volume 35 (1977)
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Volume 34 (1977)
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Volume 33 (1976)
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Volume 32 (1976)
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Volume 31 (1976)
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Volume 30 (1976)
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Volume 29 (1975)
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Volume 16 (1972)
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Volume 14 (1972)
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Volume 13 (1971)
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Volume 9 (1970)
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Volume 8 (1970)
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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)