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Volume 9,
Issue 1,
1970
Volume 9, Issue 1, 1970
- Articles
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The Effect of Growth Rate in Continuous-flow Cultures on the Replication of Rubella Virus in BHK Cells
More LessSUMMARYBaby hamster kidney cells infected with rubella virus were grown in continuous flow culture to investigate the effect of growth rate on virus replication. Both cell and virus concentration varied with growth rate in normal Eagle’s medium but were independent of growth rate in phosphate-limited medium. In both media, virus production rate increased with increasing growth rate but there was a concomitant increase in the fraction of the cell population that was shedding virus, so it is not known if there was a significant increase in the synthetic rate at the cellular level. A sharp decline in virus titre followed each change in dilution rate or the onset of phosphate limitation. From the kinetics of the decline it appears that the apparatus for virus synthesis was not renewed during the 40 to 60 hr following perturbation; existing synthetic apparatus washed out exponentially without detectable decay. In continuous flow cultures, growth could be maintained for months without reduction in virus titre, complement-fixing antigen or antibody-inducing capacity.
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Changes in the Ribosomes Extracted from Mung Beans Infected with a Strain of Tobacco Mosaic Virus
More LessSUMMARYVirus infection causes an increase in the quantity of ribosomes extracted from the hypocotyls of Mung beans. Though this increase is not confined to a particular size of ribosome, presumptive virus messenger RNA is associated predominantly with polyribosomes composed of nine or more monoribosomes.
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Envelope Antigen Relationships among Three Hamster-specific Sarcoma Viruses and a Hamster-specific Helper Virus
More LessSUMMARYThe immunological relationships among three hamster-specific sarcoma viruses and a non-sarcomagenic virus were determined by neutralization and interference tests. These viruses were all derived from hamster tumours induced originally by murine sarcoma viruses but were no longer capable of growth on mouse cells. The four viruses shared at least one envelope antigen responsible for neutralization reactions. Specific interference for the sarcoma viruses was obtained in cultures infected with the non-sarcomagenic virus. In both assays these viruses were clearly distinguishable from murine C-type viruses.
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Immunological Identity of the Group-specific Antigen of Hamster-specific C-type Viruses and an Indigenous Hamster Virus
More LessSUMMARYAntisera prepared in guinea-pigs against a purified internal virion antigen of a hamster-specific C-type virus reacted with an ether-stable antigen derived from several hamster-specific viruses and an indigenous hamster virus. Reactions of identity were obtained in immunodiffusion tests between all virus preparations while no reactions were obtained with uninfected cells and murine C-type virus preparations. Guinea-pig antiserum to the murine C-type virus gs antigen did not react with any of the hamster virus preparations. This pattern of specificity was maintained in complement-fixation tests.
Based on these data and the envelope antigen identity of the hamster-specific sarcoma viruses established in the accompanying paper, these viruses, originally recovered from hamster tumours induced by murine sarcoma viruses, are considered to be pseudotype sarcoma viruses possessing the antigens of the indigenous hamster C-type virus and the sarcoma gene(s) of the original tumour inducing murine viruses. Our current preferred nomenclature for the hamster-specific viruses is based on these considerations.
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Heat-stable and Density Mutants of Phages T1, T3 and T7
More LessSUMMARYThe coliphages T1, T3 and T7 rapidly lost infectivity when incubated at 60° in saline-citrate medium. From the survivors of heat-inactivated wild-type phage stocks heat-stable (st) mutants were isolated, which all had a reduced buoyant density. The st mutant phages of T3 and T7 contained 3 to 5% less DNA than their wild-type parent, while no loss of DNA could be detected for T1 st mutants. This correlation between heat stability and reduced density was confirmed by showing that a mutant of T3 selected for its lighter density had also mutated to heat-stability.
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The Influence of Ultraviolet-inactivated Sendai Virus on Marek’s Disease Virus Infection in Tissue Culture
More LessSUMMARYThe presence of ultraviolet-inactivated Sendai virus increased the transfer of Marek’s disease virus from infected to uninfected cultured chick kidney cells. This effect was seen after incubation of infected and uninfected chick kidney cells in the presence of ultraviolet-inactivated Sendai virus at 4°. There was only a slight further increase in transfer of infection with subsequent incubation at 37°. The close apposition of infected and uninfected cells occurring during the agglutination produced by treatment with ultraviolet-inactivated Sendai virus in the cold, rather than complete cell fusion may have been the main means by which treatment with ultraviolet-inactivated Sendai virus increased the transfer of infection.
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A Method for Assessing the Size of a Protein from its Composition: its Use in Evaluating Data on the Size of the Protein Subunits of Plant Virus Particles
More LessSUMMARYA method is described for assessing the possible size of a protein from its amino acid composition. This method is then used to re-examine published data and to estimate the sizes of the proteins in the particles of various plants viruses. Some of the results obtained agree with the published reports, others do not.
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Inhibitory Effect of Ultraviolet-inactivated Vesicular Stomatitis Virus on Initiation of DNA Synthesis in Cultured Chick Embryo Cells
More LessSUMMARYThe initiation of partially synchronized DNA synthesis was induced by medium replacement on stationary monolayer cultures of chick embryo cells. The synthesis of DNA started at 4 hr and continued for 8 hr, and cells divided within 15 to 18 hr. The onset of DNA synthesis and subsequent cell division were inhibited by u.v.-inactivated vesicular stomatitis virus if the cells were infected before the onset of DNA synthesis. In contrast, if the cells were infected during the S phase, the continuing DNA replication and subsequent cell division were not inhibited. Thus the selective inhibition of the flow of G1 cells to the S phase was demonstrated in the cells infected with u.v.-inactivated vesicular stomatitis virus.
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Attachment of Two Myxoviruses to Ciliated Epithelial Cells
More LessSUMMARYIt is thought that influenza and related viruses enter susceptible cells, such as those of tissue cultures and the chorioallantois, by being adsorbed to the surface and then taken in by an active process termed ‘viropexis’. It has been suggested that this active process resembles phagocytosis (Fazekas de St Groth 1948). However, influenza viruses commonly invade the ciliated epithelium of the respiratory tract of the intact host, which is thought not to be actively phagocytic. Organ cultures of such epithelium are extremely susceptible to infection (Hoorn & Tyrrell, 1969). It was therefore of interest to use these to investigate the mechanism of entry of influenza viruses into ciliated epithelial cells; it was uncertain whether the primary target cells would be the ciliated or the mucus-secreting cells. As infection was so efficient, it seemed likely that the virus might ‘exploit’ in some way the sweeping action of the cilia and, rather than being moved on by their activity, might attach and then enter the cells directly or indirectly. Further studies on the entry of virus into non-ciliated cells appeared during this work and these will be discussed later.
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Coiled Structure of the Nucleocapsid of Avian Myeloblastosis Virus
More LessLittle is known about the structure of the nucleocapsid of the RNA oncogenic viruses. Although the nucleocapsid can be observed within virus particles or after isolation from them in negatively stained preparations, subunit arrangement has not been resolved in this group of viruses. While the disruption of the virus envelope of myxoviruses results in a release of the helical nucleocapsid which contains the RNA (Fraenkel-Conrat, 1968), similar disruption of RNA oncogenic viruses by tween + ether or deoxycholate seems to be incomplete, for the method apparently yields intact nucleocapsids (Thé & O’Connor, 1966; Sarkar & Moore, 1968; Calafat & Hageman, 1969).
This communication describes a method for the disruption of AMV with Brij 58 and deoxycholate which yields nucleoids of loosely coiled structure. An approach to the isolation of the nucleocapsid components of AMV was suggested by the method of Godson & Sinsheimer (1967) for lysis of Escherichia coli cells.
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Separation of Adenovirus Penton Base Antigen by Preparative Gel Electrophoresis
More LessStudies on the three major adenovirus structural antigens, designated hexons, pentons (a base plus a fibre) and fibres (Ginsberg et al. 1966), have been reviewed extensively (Norrby, 1968; Schlesinger, 1969). The availability of purified preparations of hexon, fibre and whole penton has made the physicochemical and immunological characterization of these virus components possible. However, the properties of the penton base, a component also known to be synthesized independently in infected cells, have received relatively little attention, mainly because of the lack of a method for its purification. Present information on the properties of the penton base is derived from analytical data on partially purified materials or from the study of whole penton (Pettersson & Hoglund, 1969; Wadell & Norrby, 1969). In the present report we describe a simple method for the preparation of physicochemically and immunologically pure adenovirus type 5 (ad. 5) penton base.
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