- Volume 17, Issue 1, 1972
Volume 17, Issue 1, 1972
- Articles
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Protection Against Aerosol-inactivation of Bacteriophage T1 by Peptides and Amino Acids
More LessSUMMARYAerosol-inactivation of bacteriophage T1 is prevented by peptone and by apolar amino acids (leucine, phenylalanine). The protecting concentration is related to the salt concentration in the spray-medium, which determines the amino acid concentration in the aerosol particle after evaporation to equilibrium. The protective action of surface active agents supports the hypothesis that inactivation is due to surface inactivation. The surface occupation of the protecting amino acids was calculated with the Gibbs adsorption formula and agrees with amounts necessary to cover the air/water interface, thus preventing the phage from reaching the surface.
The decrease of amino acid concentration in the aerosol particle by surface adsorption is calculated in the appendix.
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Specific Inhibition of Poliovirus Induced Blockade of Cell Protein Synthesis by a Thiopyrimidine Derivative
More LessSUMMARYA thiopyrimidine derivative, i.e. ethyl-2-methylthio-4-methyl-5-pyrimidine carboxylate (S-7) is capable of preventing both poliovirus RNA synthesis and virus induced inhibition of cell protein synthesis.
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The Requirement for Calcium in Infection with Lactobacillus Phage
More LessSUMMARYCalcium ions were specifically required for a stage in the formation of phage-infected cells in the growth cycle of PL-1 phage active against Lactobacillus casei atcc 27092. Both the adsorption of phage on to the host cells and the intracellular multiplication of phage were independent of the presence or absence of calcium ions. The optimum pH for successful infection was 5.5 to 6.0 and the optimum temperature was approximately 30 °C. Among the divalent salts tested SrCl2 was as effective as CaCl2 in allowing infection, whereas MgSO4, MnCl2, BaCl2, BeSO4, ZnSO4 and CoSO4 were not. The impairment of infection by lack of calcium ions could not be reversed by the delayed addition of CaCl2.
An experiment with host cells infected with [32P]-labelled phage showed that calcium ions were required for the penetration of phage genomes into the host cells. The host cells, which had adsorbed phage but not permitted the penetration of phage genomes owing to the absence of calcium ions, were not killed by the phage particles. PL-1 phage infection was, therefore, abortive in the absence of calcium ions owing to the inhibition of a stage of the formation of phage-infected cells involving penetration.
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Immunological Specificity of the Glycoproteins of Herpes Simplex Virus Subtypes 1 and 2 *
More LessSUMMARYThe glycoproteins of cells infected with herpes simplex virus 1 or 2 (HSV-1 or HSV-2) were solubilized with non-ionic detergent NP-40 and electrophoresed in acrylamide gels. At least 12 bands containing virus glycoproteins were formed. The HSV-1 glycoproteins correspond in electrophoretic mobility to structural proteins in the HSV virions and to the virus proteins in plasma membranes of infected cells. All virus glycoproteins were bound to immunoadsorbent columns made by cross-linking either homologous or heterologous antibody. Immunoadsorbent columns readily discriminated between host and virus glycoproteins. The differentiation between HSV-1 and HSV-2 glycoproteins varied; the degree of specificity of the immunoadsorbent gels was related to the specificity exhibited by the antisera in neutralization tests. All immunoadsorbent antibody gels tested bound homologous glycoproteins in proportions similar to those in the input extract. Immunoadsorbent antibody gels of high specificity bound disproportionate amounts of only a few heterologous glycoproteins. Immunoadsorbent antibody gels of low specificity reacted with heterologous glycoprotein preparations as if they were a homologous preparation.
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The Application of DEAE-cellulose Column Chromatography to the Selection of S+ Revertants and Determination of Reversion Frequency in Populations of S- Mutants of Fowl Plague Virus
More LessSUMMARYA method has been developed for selection of revertants present at low frequency in a population of fowl plague virus. It was based on the differences in elution from DEAE-cellulose columns of the original large-plaque variant (S+) and polycation-dependent plaque-size mutants (S−). It was possible to estimate low frequencies of revertants in this way.
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Characterization of Viruses Obtained after Cell Fusion or Transfection of Chicken Cells with DNA from Virogenic Mammalian Rous Sarcoma Cells
More LessSUMMARYViruses recovered after transfection of chicken cells with DNA isolated from virogenic mammalian cells were characterized by serum neutralization, virus interference and host range tests. The virus obtained after transfection with DNA from XC cells containing the genome of the prague strain of Rous sarcoma virus (pr-RSV) had the properties of subgroup C avian sarcoma viruses. The virus isolated after transfection with DNA from RSCH cells containing the genome of the schmidt-ruppin strain of Rous sarcoma virus (sr-RSV) exhibited the properties of subgroup D viruses. The subgroup classification of described viruses corresponds with classes of virus genomes present in virogenic cells.
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Amino Acid Composition of Polypeptides from Influenza Virus Particles
More LessSUMMARYThe neuraminidase, the membrane protein, the ribonucleoprotein (nucleocapsid protein) and the light and heavy polypeptide chains of the haemagglutinin subunits were isolated from particles of influenza virus type A0 (strain bel) and type B (strain lee). Each of these substances migrated as a single component during electrophoresis on SDS-polyacrylamide gels. The neuraminidase of type A2 influenza was isolated from the A0-A2 recombinant virus, X-7F1. This enzyme contained two polypeptides differing slightly in electrophoretic mobility.
This paper gives the amino acid composition of the individual polypeptides from the type A0 and type B influenza viruses and the neuraminidase protein from X-7F1 virus.
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Synthesis in vitro by Bacterial RNA Polymerase of Simian Virus 40-specific RNA: Multiple Transcription of the DNA Template into a Continuous Polyribonucleotide
More LessSUMMARYThe mol. wt. of the single-stranded RNA molecules synthesized in a cell-free system on simian virus 40 (SV40) DNA by Escherichia coli RNA polymerase was determined at intervals after the initiation of the reaction. Chain elongation of the RNA, under the experimental conditions used, took place at an average rate of 5 nucleotides/s. Thus single-stranded RNA molecules of 1.5 × 106 mol. wt. resulting from continuous transcription of one turn of the circular SV40 genome did not appear until about 20 min after initiation of the reaction. After 40 to 80 min, molecules with mol. wt. equal to or greater than the mol. wt. of the DNA template strand (⩾ 1.5 × 106) accounted for 25 to 50% of the mass of the RNA population. Up to 25% of the RNA synthesized at that time had mol. wt. equal to or larger than 3 × 106. The results indicate that the cell-free system used does not contain specific factors or signals which would cause the E. coli RNA polymerase to terminate transcription.
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Studies on the Cytopathogenicity of Newcastle Disease Virus: Effect of Lectins on Virus Infected Cells
More LessSUMMARYThe infection of chick embryo (CE) and baby hamster kidney (BHK) cells with Newcastle disease virus (NDV) strains herts, warwick, texas, field pheasant, lamb essex or beaudette c increased their susceptibility to agglutination by the lectins, concanavalin A (Con A) and wheat germ agglutinin (WGA). The agglutination reaction with Con A and WGA was inhibited by α-methyl-d-glucopyranoside and N-acetyl-glucosamine, respectively. The agglutination of purified virus particles from these strains by the lectins indicated that lectin-receptors on the cell surface were incorporated into the virus envelope.
A correlation was found between the change in cell agglutination behaviour after infection and the virus-induced alterations of the cell coat material. In contrast, CE and BHK cells infected with the avirulent queensland or ulster strains of NDV were not agglutinated by Con A or WGA and no changes were detected in the cell coat material. The greater susceptibility to agglutination by lectins found for cells infected with the more virulent NDV strains required the synthesis of virusinduced proteins. The relationship between agglutination and changes in the cell coat material is discussed.
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Effects of Cycloheximide and Chloramphenicol on the Multiplication of Tobacco Necrosis Virus
More LessSUMMARYInfectivity studies have shown that the multiplication of tobacco necrosis virus can be inhibited by cycloheximide but not by chloramphenicol, and that it is likely that cycloheximide inhibits the synthesis of at least two proteins necessary for multiplication.
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Electron Microscope Study of Double-stranded Ribonucleic Acid of Influenza Virus Infected Cells
More LessSUMMARYVirus-specific double-stranded RNA molecules extracted from x7 strain influenza virus infected cells were characterized by electron microscopy. Molecules 0.33, 0.67, and 1.0 μm in length were frequently observed, and possibly five or more subunits could be identified.
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High Interferon Producing Line of Transformed Murine Cells
More LessDuring a comparative study of the interferon system in normal and virus-transformed murine cells, a clonal line was observed to produce unusually high yields of interferon. This report describes some variables which influence the interferon yield.
Procedures for the establishment of Moloney sarcoma virus (MSV)-transformed cell clones have been described previously (Bassin, Tuttle & Fischinger, 1970). The twice cloned line C-243-3 was received from Dr. Bassin, National Cancer Institute, Bethesda, Maryland. The line was derived by transforming 3T3FL cells, a subline of the original Swiss 3T3 cell line (Todaro & Green, 1963) under conditions permitting infection by MSV in the absence of associated ‘helper’ leukaemia virus. The cells contain the MSV genome but do not release infectious MSV or leukaemia virus. However, the cells do release small quantities of non-infectious, non-transforming, virus-like particles. Such cells have been termed S + L - cells (Bassin et al. 1970, 1971).
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The Multicomponent Nature of Broad Bean Mottle Virus and its Nucleic Acid
More LessBroad bean mottle virus (BBMV) is a spherical plant virus belonging to the same group as brome mosaic virus (BMV) and cowpea chlorotic mottle virus (CCMV) (Bancroft, 1970). BMV and CCMV have recently been shown to have divided genomes (Lane & Kaesberg, 1971; Bancroft, 1971) contained in virus particles which sediment as a single species. The RNA from BBMV, when examined in the ultracentrifuge, has been shown to be heterogeneous (Kodama & Bancroft, 1964), consisting of a 17S infectious species, and a 10S species (Bancroft et al. 1968) which was considered to be a degradation product about one-third the size of the large piece. As with the other members of this group, further heterogeneity of the fastest sedimenting species has been found on electrophoresis of the RNA on polyacrylamide gels (Fowlks & Young, 1970).
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A Bacteriophage T4 Mutant Defective in Protection Against Superinfecting Phage
More LessWhen Escherichia coli is infected by bacteriophage T4 and after a few minutes superinfected by additional phage, the secondary phage genome is prevented from being expressed and from contributing genetic information to progeny phage. This phenomenon, known as superinfection inhibition, was first observed by Dulbecco (1952). Further work was carried out by Graham (1953) and has been reviewed by Adams (1959) and Campbell (1967). Several questions have arisen concerning the mechanism of this phenomenon. Is the DNA of the superinfecting phage broken down by the DNases present in the cell, and is this DNA degradation essential for the inhibition? Is there a barrier at the membrane level which prevents the superinfecting DNA from getting into the cell? Does superinfection inhibition depend on the expression of a function or functions by the primary phage which exclude the superinfecting phage? Graham (1953) using high streptomycin concentrations to inhibit nuclease action observed that superinfecting phage were nevertheless excluded.
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Transmission of Tobacco Mosaic Virus by Myzus persicae
More LessIt is well known that many plant viruses can be transmitted by aphids, but the highly infectious tobacco mosaic virus (TMV) seems to have no aphid vector. Only Hoggan (1934) reported a very low level of transmission which, however, has not been substantiated (Orlob, 1963; Pirone, 1969). Some progress on this problem was made when Teakle & Sylvester (1962) showed that TMV could be inoculated by aphids placed on virus-covered leaves. More recently we demonstrated that aphids can transmit TMV from a virus-covered leaf to a healthy leaf (Lojek & Orlob, 1969). Now we wish to describe experiments in which the green peach aphid, Myzus persicae Sulz., transmitted TMV from tomato and doubly infected tobacco.
The following plants were used as virus sources: Nicotiana tabacum L. var. Havana or Lycopersicon esculentum L. var. Potentate for TMV or TMV/cucumber mosaic virus (CMV); N. tabacum var. Xanthi n.c. for CMV and potato virus Y (PVY).
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Morphological Studies on Simian Virus S.A. 11 and the ‘Related’ O Agent
H. J. Els and G. LecatsasStudies on viruses recovered from South African Cercopithecus monkeys have been carried out by Malherbe & Harwin (1957) and Malherbe, Harwin & Ulrich (1963). One such virus, designated S.A. 11 (strain h96) was isolated from a rectal swab taken from a healthy vervet monkey in 1958 (Malherbe & Strickland-Cholmley, 1967). This virus has not yet been characterized morphologically. A virus isolated from intestinal washings of cattle and sheep (Malherbe, Strickland-Cholmley & Geyer, 1967) and designated O agent, showed eosinophilic cytoplasmic inclusions in monkey kidney cell cultures similar to those of S.A. 11 (Malherbe & Strickland-Cholmley, 1967). No published information is available on the structure of this virus. On the basis of similarities in serology, pH instability, resistance to desoxycholate and certain other characteristics, the viruses are considered to be virtually identical (Malherbe & Strickland-Cholmley, 1970). In addition Verwoerd (1970) has suggested that S.A. 11 is similar in structure to the bluetongue-type viruses.
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Effect of Plasma Membrane Lipid Composition on Cellular Susceptibility to Virus-induced Cell Fusion
More LessIt is well known that cells differ significantly in their susceptibility to virus-induced fusion. Evidence from many reports indicates that in general cells from established cell lines are more susceptible to virus-induced fusion than are primary or secondary diploid cell strains (for review see Poste, 1970a). The factors that determine these differences in cellular response are poorly understood. Although the process of cell fusion requires fusion of the plasma membranes of apposed cells, the effect of the composition of the plasma membrane on cell fusion capacity has received little attention. Klenk & Choppin (1969, 1970) found significant differences in the molar ratios of cholesterol to phospholipid in the plasma membranes of a range of cell types showing different susceptibilities to fusion induced by SV5 virus.
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Two Properties of Raspberry Ringspot Virus Determined by its Smaller RNA
More LessRaspberry ringspot virus (R/1:2.4/43 + 1.4/30 (or 2 × 1.4/46):S/S:S/Ne, nepovirus group) is a multicomponent plant virus with two sizes of RNA having mol. wt. of 2.4 × 106 (RNA-1) and 1.4 × 106 (RNA-2) (Murant et al. 1972). When obtained by centrifuging in sucrose density gradients or by electrophoresis in polyacrylamide gels, preparations of RNA-2 mostly did not infect the local lesion assay host, Chenopodium amaranticolor Coste & Reyn., and those of RNA-1 were only moderately infective, whereas mixtures of the two kinds of preparation were very infective (Harrison, Murant & Mayo, 1972). No such increase in infectivity occurred when one RNA species from raspberry ringspot virus was mixed with the other from tobacco ringspot virus (another nepovirus), or when either of the RNA species from raspberry ringspot virus was u.v. irradiated before use. A possible explanation of these results is that each RNA species carries genetic information not carried by the other.
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The Density of Poliovirus-specific Polysomes
More LessIn homogenates of HeLa cells 10 to 20% of the ribosomes are bound to membranous structures (Attardi, Cravioto & Attardi, 1969; Rosbash & Penman, 1971a; Roumiantzeff, Maizel & Summers, 1971). After treatment with sodium deoxycholate (DOC) to dissolve the membranes, some of these ribosomes equilibrate in density gradients of CsCl at the same position as free ribosomes but others are less dense, having a higher ratio of protein to RNA (Rosbash & Penman, 1971b). Large polysomes bearing virus RNA appear in cells infected with poliovirus in the presence of actinomycin D (Penman et al. 1963). These polio polysomes are attached to membranes until treated with DOC (Penman, Becker & Darnell, 1964; Caliguiri & Tamm, 1970; Roumiantzeff et al. 1971). We report here studies of their density in CsCl gradients.
HeLa cells grown in suspension (Harris & Watts, 1962) were resuspended in phosphate-buffered saline containing Ca+ and Mg+ (Oxoid Ltd.) at 107 cells/ml and kept at 0 °C for 30 min after adding about 50 p.f.u./cell of poliovirus type 1, strain ts+ (Cooper, Johnson & Garwes, 1966).
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