- Volume 10, Issue 3, 1971
Volume 10, Issue 3, 1971
- Articles
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Some Factors Affecting the Survival of Airborne Viruses
More LessSUMMARYThe response of aerosolized viruses to relative humidity depended greatly on the composition of the fluid from which the viruses were sprayed. For example, the removal of salts from the spray fluid diminished the loss of infectivity of Langat virus (a group B arbovirus) at intermediate relative humidities. Salts were less toxic towards aerosolized Semliki Forest virus (a group A arbovirus) but did cause some loss of infectivity at higher relative humidities after prolonged storage of the aerosol. Polyhydroxy-compounds reversed the virucidal effects of salts on arboviruses. The removal of protein from the spray suspensions of arboviruses caused rapid loss of infectivity in the aerosol at very high relative humidities but had no detrimental effect at lower relative humidities. Poliovirus and T coliphage, which possess no structural lipid, retained high levels of infectivity following aerosolization at relative humidites of 70% or above; at lower relative humidities they were inactivated rapidly. This rapid inactivation was increased further at lower solute concentrations of the spray fluid.
The infectivities of aerosolized polioviruses and coliphages depended on the mode of rehydration during collection of the aerosols, but the infectivities of arboviruses in aerosols were unaffected by this. Atmospheric oxygen was not toxic to viruses in the aerosol state.
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Infectivity of Molecular Forms of Simian Virus 40 DNA
More LessSUMMARYThe conversion of superhelical (Form I) SV40 DNA to nicked molecular forms was studied by incubating SV40 [3H]DNA for to 2 hr with monolayer cultures of monkey, human, or mouse cells in the presence of DEAE-dextran. The superhelical and the nicked DNA forms were then extracted from the cultures and separated by equilibrium centrifugation in caesium chloride-ethidium bromide (CsCl-EtBr) density gradients. About 66 and 42% of the Form I [3H]DNA was converted to nicked DNA during 2 hr of adsorption to monkey and to human cells, respectively. Form I DNA was adsorbed less by mouse kidney cells than by monkey cells, and only about 25% of the input DNA was converted to nicked forms in 2 hr. The specific infectivities (p.f.u./counts/min.) of the SV40 DNA extracted from the cultures were about the same as those of the input DNA, despite the fact that as much as 69% of the extracted DNA represented nicked molecular forms.
Cultures of monkey cells infected with SV40 were synchronized by treatment with 1-β-d-arabinofuranosylcytosine (ara-C) from 2 to 24 hr after infection and pulse-labelled with [3H]thymidine at 37 to 39 hr after infection. The pulse-labelled Form I and nicked forms of SV40 [3H]DNA were extracted from the cells, purified by CsCl-EtBr equilibrium centrifugation and velocity sedimentation in sucrose gradients, and assayed for infectivity. The nicked (Form II) SV40 DNA obtained from infected cells was about half as infective as superhelical (Form I) SV40 DNA.
When SV40 [3H]DNA was incubated with monkey kidney cells for 6 to 24 hr, 90 to 97% of the Form I DNA was converted to nicked molecular forms and specific infectivities were reduced by 85 to 98%, respectively.
These results suggest that minimally nicked SV40 DNA was about as infectious as superhelical (Form I) DNA in the SV40 DNA+DEAE-dextran plaque assay but that multiply nicked SV40 DNA was much less infectious.
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Replication of Venezuelan Equine Encephalomyelitis Virus in Suspension Cell Cultures Grown in Serum-free and Defined Media
More LessSUMMARYVarious mammalian cells propagated in serum-free and chemically defined media yielded high titres of Venezuelan equine encephalomyelitis virus. Some difference in maximum titres was noted, depending upon the medium employed. Of the two serum-free media tested, lactalbumin hydrolysate medium was more effective than the chemically defined medium in supporting virus growth. The addition of serum to serum-free cultures at the time of virus inoculation had a pronounced effect characterized by a delay followed by a burst of virus replication to very high titres. Thus, the degree of replication of Venezuelan equine encephalomyelitis virus appeared to be influenced by a variety of unknown nutritional factors.
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Failure to Detect Homology between the DNA of the Shope Fibroma Virus and the DNA of the Sensitive Cell
More LessSUMMARYThe nucleic acid of the Shope fibroma virus, a virus which induces tumours in the rabbit, does not show any homology with the DNA of the cell of this animal. The relationship of this fact to the oncogenic mechanism of this virus is not clear.
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The Influence of Inhibitors of Macromolecular Syntheses on Capacity of Herpes Simplex Virus to Induce Chromosomal Damage
L. Donner and Éva GönczölSUMMARYWhen either actinomycin D or puromycin is added to cell cultures at the time of infection with herpes simplex virus, or 1 hr later, there is an inhibition of chromosomal damage induced by virus. On the other hand, cytosine arabinoside considerably potentiates the capacity of herpes simplex virus to induce chromosomal damage. This finding supports the view that chromosomal changes induced by virus are probably due to the action of early enzymes controlled by virus genes.
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Studies on Lipid Metabolism in Cells Infected with Adenovirus
More LessSUMMARYLipid metabolism in cells infected with adenovirus type 5 was studied using [32P]orthophosphate and [14C]acetate precursors. Within the first 6 hr after infection, uptake of isotopes into cellular lipids was increased, although at this time no qualitative changes in the pattern of labelling were observed. At 12 to 18 hr after infection there was a markedly increased uptake of [14C]acetate into cellular triglycerides. Increased lipid metabolism was demonstrated using ultravioletirradiated virus and purified penton base capsid subunits as well as whole infective virus. Highly purified adenovirus type 5 from cells labelled with [32P]orthophosphate during infection contained small amounts of radioactive lipid; the data presented suggest that this represented cellular lipid which remained attached to the virus, rather than lipid intrinsic to the virus particle.
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Volumes and issues
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Volume 105 (2024)
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Volume 14 (1972)
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Volume 12 (1971)
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Volume 11 (1971)
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Volume 10 (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)