bluuebunny/crossref_metadata_2025 huggingface dataset:
Isolation of a Herpes Simplex Virus-Specific Antigenic Fraction Which Stimulates the Production of Neutralizing Antibody
Authors: Cohen Gary H. , De Leon Manuel Ponce , Nichols Chris
Published: January 2020

Infection of mammalian cells with herpes simplex virus (HSV) results in the production of a number of virus-induced soluble antigens. Immunodiffusion analyses of the soluble antigen mixture (SAM) obtained from HSV-infected KB or BHK cells revealed at least six well-defined immunoprecipitin bands. Calcium phosphate chromatography (Brushite) was employed to separate one immunoprecipitin (designated CP-1) from the remaining viral and host antigens. We conclude that CP-1 is a viral-specific antigen because (i) specific antiserum, which had been repeatedly absorbed with uninfected cell extracts or serum components, still retained the capacity to react in gel diffusion with CP-1 antigen; (ii) anti-CP-1 serum reacted in gel diffusion with SAM, yielding one precipitin band in identity with the band formed against human gamma globulin; (iii) the CP-1 fraction stimulated the production of HSV-neutralizing antibody of high capacity. The last observation suggests that fraction CP-1 contains a biologically active structural component of the virus which is associated with the envelope. The CP-1 immunoprecipitin was separated from SAM by an alternative method by using a cyanogen bromide-linked immunosorbent prepared from anti-CP-1 gamma globulin. The observation that the CP-1 antigen isolated from the immunosorbent effectively blocked serum-neutralizing activity provided further evidence that neutralizing antibody was directed against CP-1. Acrylamide gel electrophoresis and immunological experiments suggest that the CP-1 antigen is in part a glycoprotein. The finding that CP-1 contains only one antigenic component of the virus will permit future biological studies to be made with a monoprecipitin antiserum. In addition, the techniques described in this paper represent initial steps in the purification of HSV antigens.
Sendai Virus-Induced Transcriptase from Infected Cells: Polypeptides in the Transcriptive Complex
Authors: Stone H. O. , Kingsbury D. W. , Darlington R. W.
Published: January 2020

A Sendai virus-induced transcriptase-template complex was isolated from the cytoplasm of infected cells by combined sedimentation and isopycnic centrifugation. This transcriptive complex banded at 1.27 g/cm
3
in D
2
O-sucrose gradients. It contained two polypeptides, the viral nucleocapsid structure unit (molecular weight, 60,000) and the largest virion polypeptide (molecular weight, 75,000). The buoyant density, chemical composition, and electron microscopic appearance of the transcriptive complex indicate a structure like that of viral nucleocapsids.
Serological Analysis of the Deoxyribonucleic Acid Polymerase of Avian Oncornaviruses I. Preparation and Characterization of Monospecific Antiserum with Purified Deoxyribonucleic Acid Polymerase
Authors: Watson K. F. , Nowinski R. C. , Yaniv A. , Spiegelman S.
Published: January 2020

Monospecific antiserum was prepared against purified deoxyribonucleic acid (DNA) polymerase from avian myeloblastosis virus (AMV). Immunodiffusion assay with purified DNA polymerase revealed that the anti-DNA polymerase serum formed one precipitation band, whereas no reaction with any of the seven major structural proteins of AMV was observed. The antiserum also demonstrated enzyme-neutralizing antibody activity that was associated with the immunoglobulin G fraction. There was no difference in the neutralization of DNA polymerase activity directed by ribonucleic acid (RNA), DNA, or RNA-DNA hybrid templates.
Mechanism of Mengo Virus-Induced Cell Injury in L Cells: Use of Inhibitors of Protein Synthesis to Dissociate Virus-Specific Events
Authors: Collins F. D. , Roberts W. K.
Published: January 2020

L cells were infected with Mengo virus in the presence of varying concentrations of protein synthesis inhibitors (azetidine-2-carboxylic acid,
p
-fluorophenylalanine, puromycin), and examined with respect to the effects of the inhibitors on several features of virus-induced cell injury. The virus-specific events in the cells could be dissociated into three groups, based on their sensitivity to the inhibitors: (i) viral ribonucleic acid (RNA) synthesis, bulk viral protein synthesis, and infectious particle production, all of which were prevented by low inhibitor concentrations; (ii) the cytopathic effect (CPE) and stimulation of phosphatidylcholine synthesis, which were sensitive to intermediate concentrations of the inhibitors; and (iii) the virus-induced inhibitions of host RNA and protein synthesis, which were resistart to the inhibitors of protein synthesis except at very high concentrations. It is concluded from this that the virus-induced CPE and stimulation of phosphatidylcholine synthesis are not consequences of the inhibition of cellular RNA or protein synthesis. Analysis of the virus-specific protein and RNA synthesized at several concentrations of azetidine and puromycin suggests that the CPE may be induced by a viral protein precursor. Virus-induced inhibition of host RNA and protein synthesis occurred at azetidine concentrations which blocked the synthesis of over 99.7% of the total viral RNA and over 99% of the viral double-stranded RNA (dsRNA). Calculations show that this would correspond to less than 150 dsRNA molecules per infected cell, resulting in a dsRNA-polysome ratio of less than 1:1,000; this indicates that host protein synthesis cannot be inhibited by an irreversible binding of dsRNA to polysomes.
Procedure for the Preparation of Milligram Quantities of Adenovirus Messenger Ribonucleic Acid
Authors: Bhaduri Saumya , Raskas Heschel J. , Green Maurice
Published: January 2020

Late after adenovirus 2 infection (18 hr), nearly all newly synthesized polysomal messenger ribonucleic acid (mRNA) is viral specified. Large amounts of adenovirus mRNA have been purified by utilizing membrane filtration at high ionic strength. With this procedure, molecules that contain polyadenylic acid [poly (A)] tracts are bound selectively, and ribosomal RNA can be separated from the viral mRNA which contains poly(A). Polysomal RNA synthesized 18 hr after infection was labeled in the presence of 0.02 μg of actinomycin D per ml and extracted at
p
H 9.0. This RNA annealed 40% to 3 μg of adenovirus 2 deoxyribonucleic acid; the RNA selected by membrane filtration bound 80% under the same conditions. The RNA eluted from membrane filters was 80 to 90% greater than 18
S
and contained species migrating as 31, 27, and 24
S
. Binding of polysomal RNA to individual membrane filters was linear, using as much as 300 μg of RNA per membrane. A 1.1-mg amount of viral RNA was prepared from 17.7 mg of polysomal RNA that had been purified by extraction at
p
H 9.0.
Isolation and Characterization of Subacute Sclerosing Panencephalitis Virus Nucleocapsids
Authors: Yeh Jen , Iwasaki Yuzo
Published: January 2020

Nucleocapsids from subacute sclerosing panencephalitis (SSPE) virus-infected CV-1 cells were concentrated by differential centrifugation employing sucrose cushion techniques and further purified by centrifugation through a linear CsCl density gradient. The bouyant density of
3
H-uridine-labeled nucleocapsids in CsCl was found to be 1.31 g/cm
3
. Ultraviolet absorption spectra of the purified SSPE nucleocapsid showed an absorption maximum at 260 to 265 nm and a 280/260 ratio that corresponded to a nucleic acid content of approximately 4.3%. Negatively stained preparations of SSPE nucleocapsids were found to have a width of 18 ± 1 nm, a periodicity of 5 to 6 nm, and a length between 1-1.4 μm, with the greatest number at 1.3 μm.
The Glycoprotein of Vesicular Stomatitis Virus Is the Antigen That Gives Rise to and Reacts with Neutralizing Antibody
Authors: Kelley J. Michael , Emerson Suzanne U. , Wagner Robert R.
Published: January 2020

The glycoprotein, but no other virion protein, of vesicular stomatitis virus was solubilized by the nonionic detergent Triton X-100 in low ionic strength buffer. The solubilized viral glycoprotein induced the synthesis of antibody that formed a single precipitin line with the glycoprotein and that neutralized the infectivity of the virus. The neutralizing activity of the antibody was efficiently blocked by purified glycoprotein.
Electrophoretic and Other Properties of Bacteriophage Qβ: the Effect of a Variable Number of Read-Through Proteins
Authors: Radloff Roger J. , Kaesberg Paul
Published: January 2020

When subjected to electrophoresis in polyacrylamide gels, the virions of wild-type Qβ bacteriophage are found in a single, major, anomalously wide band. With Qβ mutant 27-2, this wide band is replaced by a set of narrow, well-defined bands. The most rapidly migrating band of the mutant, comprising less than 10% of the total, contains defective virions. These virions have sedimentation coefficients ranging from 70 to 100% of the bulk of the unfractionated mutant, they contain no read-through protein (protein IIb), and they are deficient in maturation protein and contain fragmented RNA. The second band, comprising less than 3% of the total virus, has not been well characterized. The virions in the remaining electrophoretic bands are infective. Their distribution into bands is believed due to differences in their effective volume resulting from differences in their content of protein IIb. The most rapidly migrating band of this series contains virions with a few molecules of IIb protein, whereas the more slowly migrating bands contain virions with a larger number of IIb molecules. The adjacent bands in the series contain virions which differ by approximately three IIb molecules. Wild-type Qβ virus is similar to the mutant in that the more slowly migrating virions contain more protein IIb than the more rapidly migrating virions. Their failure to resolve into distinct bands upon electrophoresis is believed due to a less restricted packing of protein IIb into their virions. Both wild-type Qβ and mutant 27-2 also have 1 to 5% of the virions in the form of dimers which migrate with approximately one-half the mobility of the respective monomer forms. When the average amount of IIb per virion is increased by growth of the virus in a UGA suppressor strain, the electrophoretic pattern is altered. In the case of wild-type Qβ, the single band is wider, whereas with Qβ mutant 27-2 there occurs an increased number of partially resolved narrow bands. We suggest that the structural feature responsible for the difference in electrophoretic pattern between mutant 27-2 and wild-type Qβ is the mode of IIb packing in the virions. In the mutant, the IIb proteins are found in the virions only in multiples of three, whereas wild-type virions may differ by only a single IIb protein.
Viruses of
Entamoeba histolytica
III. Properties of the Polyhedral Virus of the HB-301 Strain
Authors: Hruska Jerome F. , Mattern Carl F. T. , Diamond Louis S. , Keister David B.
Published: January 2020

Some biological characteristics and bioassay of a polyhedral virus isolated from normal-appearing strain HB-301 of
Entamoeba histolytica
are described. The virus produced lysis of susceptible strains of
E. histolytica
, yet it caused no cytopathological effect in the host strain, HB-301. The virus and host amoeba existed in an equilibrium; approximately 10
4
mean infective dose units of virus were produced per million HB-301 amoebae. Superinfection and antiviral antiserum treatment failed to disturb this equilibrium permanently. The mechanism of viral persistence in strain HB-301 amoebae remains to be determined. Purification of the virus was attempted. Ninety-nine percent of the viral infectivity was associated with a low-speed pellet which consisted of complexes of virus and cellular membranes. Various treatments of this low-speed pellet failed to release virus. Biologically active, membrane-free virus of low titer was prepared by differential centrifugation of supernatant solutions and employed in electron microscopy and other studies.
Infectivity of Lambda Heteroduplex Deoxyribonucleic Acid Molecules
Authors: Howard Bruce D.
Published: January 2020

Heteroduplex deoxyribonucleic acid (DNA) molecules were formed in vitro by denaturing and renaturing a mixture of DNAs from a variety of λ strains. The infectivity of these heteroduplexes was studied by using host-controlled modification and restriction to prevent infection by contaminating parental homoduplexes. Either strand was able to protect against degradation by restriction nucleases in vivo. A large proportion of progeny phage, which had been produced after infection with heteroduplexes containing noncomplementary base pairs at multiple loci, retained the genotype of one of the parental homoduplexes. The results indicate that conversion of heteroduplexes to homoduplexes in vivo by a DNA repair mechanism does not occur frequently. Molecules heterozygous for the
c
17 or
vir
operator mutations were not infectious; it is suggested that these mutations involve multiple base pairs.
Thermal Inactivation of Newcastle Disease Virus I. Coupled Inactivation Rates of Hemagglutinating and Neuraminidase Activities
Authors: Pierce John S. , Haywood A. M.
Published: January 2020

The thermal stability of Newcastle disease virus has been characterized in terms of the rate constants for inactivation of hemagglutinating activity (HA), neuraminidase activity (NA), and infectivity. Inactivation of HA results in the concomitant loss of NA. Infectivity, however, is much more thermolabile. Disintegration of the virus particle is not responsible for the identical rate constants for inactivation of HA and NA, nor is their parallel inactivation uncoupled in envelope fragments produced by pretreating the virus with phospholipase-C. The data indicate that a common envelope factor(s) can influence the thermal stability of both activities.
Transformation of Rat Liver Cells with Chicken Sarcoma Virus B77 and Murine Sarcoma Virus
Authors: Altaner C. , Hlavayova E.
Published: January 2020

Rat liver cells in vitro were transformed with chicken sarcoma virus B77, giving RL(B77) cells, and with murine sarcoma virus (Harvey), giving RL(MSV) cells. Rat liver cells transformed spontaneously in vitro were designated RL cells. In addition, the RL(MSV) cell line was adapted for growth in culture fluid containing 25 μg of 5-bromodeoxyuridine per ml. All cell lines were tumorigenic in 1-wk-old rats. The number of cells needed for induction of tumor growth was 1,000-fold higher in the case of RL(B77) cells in comparison with RL(MSV) cells and RL cells. No production of viral particles from any of the cell lines investigated was detected by plating concentrated supernatant fluid of the cultures on different secondary embryo cells with and without fusion by Sendai virus, by labeling with uridine-5-
3
H
, or by assay for deoxyribonucleic acid polymerase activity. The viral genome was rescued by fusion of RL(B77) cells with chicken cells. Chicken sarcoma virus rescued from (RL(B77) cells differed in plating efficiency on duck cells from B77 virus rescued from transformed rat embryo cells. No virus was rescued after fusion of RL(MSV) and RL cells with mouse, rat, or chicken embryo cells. Infectious murine sarcoma virus can be induced by 5-bromodeoxyuridine from RL(MSV) cells.
Properties of an Antigenic Glycoprotein Isolated from Influenza Virus Hemagglutinin
Authors: Eckert Edward A.
Published: January 2020

A purified antigen, HABA protein, has been derived from influenza virus concentrates by extraction with denaturing solvents. The protein lacks hemagglutinating activity but binds completely strain-specific, hemagglutination-inhibiting antibodies and induces neutralizing antibodies in experimental animals. Physicochemical characterization of HABA protein identifies it as a single homogeneous glycoprotein with a molecular weight of 78,000. On dissociation with guanidine or sodium dodecyl sulfate, in the presence of reducing agents, only one size of polypeptide with a molecular weight of the order of 40,000 is characteristic of the preparations. The data indicate that HABA protein is a dimer of HA
1
polypeptide of the influenza virus hemagglutinin substructure, and that only trace amounts of other polypeptides are present.
Extraordinary Effects of Specific Monovalent Cations on Activation of Reovirus Transcriptase by Chymotrypsin In Vitro
Authors: Borsa J. , Sargent M. D. , Long D. G. , Chapman J. D.
Published: January 2020

Activation of reovirus transcriptase activity, latent in intact virions, by digestion of purified virions with chymotrypsin (CHT) in vitro shows a stringent requirement for specific monovalent cations. Cs
+
, Rb
+
, or K
+
ions are capable of facilitating activation by chymotryptic digestion. Na
+
, Li
+
, or NH
4
+
ions are not capable of facilitating the CHT activation of polymerase activity and are antagonistic towards the effects of the facilitating ions. The data indicate that the effect of the cations is exerted on activation of the polymerase activity by CHT as opposed to an effect on polymerization per se. This effect may be important biologically in that it provides a mechanism whereby the virion can sense whether it is in an intracellular or an extracellular environment and thereby can avoid premature uncoating.
Reovirus: Effect of Noninfective Viral Components on Cellular Deoxyribonucleic Acid Synthesis
Authors: Hand Roger , Tamm Igor
Published: January 2020

We determined the effects of noninfective reovirus components on cellular deoxyribonucleic acid (DNA) synthesis. Reovirus inactivated by ultraviolet light inhibited cellular DNA synthesis, whereas reovirus cores and empty capsids did not. Both cores and empty capsids were adsorbed to cells. Adenine-rich ribonucleic acid (RNA) from reovirus, adsorbed to cells in the presence of diethyl-aminoethyl-dextran, produced a partial inhibition of DNA synthesis. RNA was synthesized in the presence of actinomycin D after infection with ultraviolet light-irradiated reovirus, and this RNA synthesis was not due to multiplicity reactivation of virus infectivity. These data suggest that viral structural proteins do not inhibit DNA synthesis and that the inhibition produced by ultraviolet-irradiated virus may be mediated in part or in toto by a newly synthesized viral product.
Effect of Viral Double-Stranded RNA on Protein Synthesis in Intact Cells
Authors: Cordell-Stewart B. , Taylor Milton W.
Published: January 2020

The addition of purified, noninfectious, double-stranded RNA of bovine enterovirus, a picornavirus, to intact cells in culture results in a rapid cessation of cellular polypeptide synthesis. This inhibition is specific for host cell protein synthesis since the translation of picornavirus-specific proteins is not affected by the double-stranded viral RNA.
Involvement of a Tryptophan Residue in the Assembly of Bacteriophages φ80 and Lambda
Authors: Deeb Samir S.
Published: January 2020

The assembly of infective particles of bacteriophages λ and φ80 from heads and tails was found to be inhibited by
l
-tryptophan and some of its analogues, most notably tryptamine. Both the rate of assembly and the final yield of phage were inhibited. The amino acid
l
-phenylalanine had a slight inhibitory effect, whereas all other amino acids found in proteins were ineffective. Evidence was presented to show that the binding of heads to tails was the affected process in the assay for assembly of infective units. The plaque-forming ability of preassembled phage was not affected by these inhibitors. Results of three different types of experiments suggest that inhibition is due to interaction of inhibitors with the head substructure. The assembly reaction is highly dependent on pH, ionic strength, and the presence of detergents.
Different Classes of Ribonucleic Acid Isolated from Lymphocytic Choriomeningitis Virus
Authors: Pedersen Ib Rode
Published: January 2020

Purified preparations of lymphocytic choriomeningitis virus (LCM virus) contain three classes of RNA. The previously described 18
s
, 23
s
, 28
s
, and 31
s
RNAs, where the 23
s
and 31
s
RNAs are viral-specific, and the 18
s
and 28
s
RNAs probably are host RNAs incorporated in the virion. Now, 4
s
, 5
s
, and 5.5
s
RNAs can be isolated as well. Thus five RNAs which migrate by acrylamide gel electrophoresis as ribosome-derived RNA can be isolated from purified LCM virus. This observation further supports the reports that arenaviruses may contain ribosomes. The ribosome-derived RNA can be synthesized both before and after the virus infection. The viral 23
s
could be a hydrogen-bonded complex forming the 31
s
RNA, or it could be contained in defective interfering LCM virus particles; these possibilities are examined.
Induction of Virus Synthesis in Polyoma-Transformed BHK-21 Cells
Authors: Folk William R.
Published: January 2020

BHK-21 cells were transformed with polyoma virus mutants Ts-a and Ts-25 by using a temperature shift from 31 to 39 C at 5 days after infection so that rescuable transformants could be isolated. Clones which yielded virus after fusion with mouse cells were scored and maintained at 39 C in the presence of antipolyoma virus antiserum. Generally, no infectious viral deoxyribonucleic acid (DNA) could be found in Hirt supernatant fractions of these lines when maintained at 39 C, but DNA-DNA reannealing measurements detected two to six viral genomes per diploid cell genome in the nuclear DNA. Fusion with permissive cells was not necessary to induce the synthesis of infectious virus; cell lines shifted to 31 C produce the equivalent of 100 viral genomes per cell after 5 days. In some cell lines up to 1% of the cells formed infectious centers upon a shift to 31 C, and 100% of the subclones of a line were inducible. Growth at 31 C selected for a noninducible population which was still transformed.
Assembly of Adenoviruses
Authors: Sundquist Bo , Everitt Einar , Philipson Lennart , Hoglund Stefan
Published: January 2020

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of purified incomplete particles of adenoviruses type 2 and 3 revealed that core proteins V and VII and capsid proteins VI, VIII, and X were absent in these particles, but they contained polypeptides not present in complete particles. Two types of incomplete particles were observed in the electron microscope, appearing as deoxyribonucleic acid-less particles with single discontinuities in the capsid structure (about 80%), or more amorphous particles resembling hexon aggregates (about 20%). The amount of incomplete and complete particles increased in parallel during the infectious cycle. Detectable amounts were found at 13 h with a maximum rate of synthesis for both particles at 24 h after infection.
3
H-labeled amino acids were incorporated into incomplete particles without a detectable lag period, but the label appeared in complete particles with a 60- to 80-min lag. Early after the pulse in pulse-chase experiments, the radioactivity was higher for incomplete particles than for complete particles and leveled off before the activity of complete particles reached a maximum. In the adenovirus type 2 system, pulse-chase experiments suggested a precursor-product relationship between incomplete and complete particles. After a short pulse, 19 h postinfection, entrance of
3
H-labeled amino acids into the hexon polypeptide of complete particles was delayed for 80 min, but no delay was observed for the labeling of the hexon polypeptide of incomplete particles. The core polypeptides appear in complete particles without a delay, also suggesting that incomplete particles were precursors to complete particles. Incorporation of
3
H-labeled amino acids into the hexon polypeptide of complete and incomplete particles was drastically decreased by inhibition of protein synthesis with emetine. However, the uptake of label into core proteins of complete particles was only decreased to 50% on inhibition of protein synthesis. The results suggest that incomplete particles are intermediates in virus assembly in vivo and that the assembly of capsid polypeptides into incomplete and complete particles is dependent on continuing protein synthesis.
Inhibition of Replication of Lactic Dehydrogenase Virus by Actinomycin
Authors: Yamazaki Shudo , Notkins Abner L.
Published: January 2020

Lactic dehydrogenase virus replicated rapidly in monolayers of primary mouse embryo cells and reached a titer of 10
8
mean infective dose per ml within 18 h after infection. Despite the high virus yield, cytopathology was not observed. Examination of the tissue culture media failed to reveal any evidence of interferon, but the virus was found to be as sensitive to mouse interferon as vesicular stomatitis virus. Incubation of mouse embryo cells with actinomycin D markedly inhibited viral replication, whereas cytosine-β-
d
-arabinofuranoside and 5-fluorodeoxyuridine had no effect on replication. These findings indicate that new DNA synthesis is not required but suggest that the intact function of cellular DNA may be required for lactic dehydrogenase virus replication.
Initiation and Direction of RNA Transcription by Vesicular Stomatitis Virus Virion Transcriptase
Authors: Roy Polly , Bishop D. H. L.
Published: January 2020

The initiation of RNA transcription by the virion-bound RNA transcriptase of vesicular stomatitis virus has been examined. Multiple initiation sequences have been observed, two of which have been characterized (pppApCpGp... and pppGpCp...) suggestive of a transcription process which can start at different sites along the template RNA. By the use of sequential labeling techniques and exonucleases, it has been determined that there is a 5′ to 3′ direction of product RNA synthesis.
New Intermediate Subviral Particles in the In Vitro Uncoating of Reovirus Virions by Chymotrypsin
Authors: Borsa J. , Copps T. P. , Sargent M. D. , Long D. G. , Chapman J. D.
Published: January 2020

Reovirus virions, grown in suspension cultures of L cells and extensively purified by density gradient and velocity gradient centrifugation after their release from cell debris by fluorocarbon extraction, are characterized by a mean particle diameter of 73 nm and a density in CsCl of 1.36 to 1.37 g/cm
3
. Treatment of intact virions by chymotrypsin (CHT) digestion in vitro converts them to subviral particles (SVP) having characteristics which are determined by the species of monovalent cation present during the digestion. In the presence of Cs
+
ions, CHT converts the virions to SVP of mean diameter 51 nm and density 1.43 to 1.44 g/cm
3
. In the presence of K
+
ions, the conversion is to SVP of diameter 51 nm and density 1.39 to 1.40 g/cm
3
. The SVP made in the presence of either Cs
+
or K
+
possess an extremely active RNA polymerase and nucleoside triphosphate phosphohydrolase (NTPase) activity in vitro and are resistant to further digestion by CHT. Treatment of intact virions with CHT in the presence of Na
+
or Li
+
ions results in their conversion to SVP of mean diameter 64 nm and density 1.37 to 1.38 g/cm
3
. Such SVP are not active in in vitro RNA synthesis or NTP hydrolysis and are resistant to further digestion by CHT even during prolonged exposure to high concentrations of enzyme. Addition of Cs
+
or K
+
ions to the digestion mixture allows conversion of the 64-nm diameter SVP to 51-nm diameter SVP in which the RNA polymerase and NTPase are active in vitro. Analysis of the proteins present in intact virions and in the different SVP reveals clear differences which indicate that the conversions are accomplished by removal or cleavage of particular species of polypeptides.
Intracytoplasmic A Particles: Mouse Mammary Tumor Virus Nucleoprotein Cores?
Authors: Smith Gilbert H. , Wivel Nelson A.
Published: January 2020

A rapid method for the isolation of intracytoplasmic A particles, the putative intracellular nucleoprotein cores of mouse mammary tumor virus (MTV), is presented. Spontaneous C3H/He mouse mammary tumors and transplantable mouse Leydig cell tumor were used as source material. Large aggregations of intracytoplasmic A particles were separated from cellular contaminants on discontinuous sucrose gradients and subsequently further purified by isopycnic banding in linear sucrose gradients. The purified particles were solubilized in sodium dodecyl sulfate, and the structural proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Purified mouse mammary tumor virions were solubilized, and their proteins were analyzed in the same way. Comparison of co-electrophoretic gels indicated a lack of correlation in the molecular size of the major structural proteins in intracytoplasmic A particles and MTV. The three major proteins of the A particles were calculated to be 80,000; 35,000; and 20,000 daltons. Five major polyacrylamide gel electrophoresis bands were obtained with purified MTV; these were 90,000; 69,000; 55,000; 37,000; and 27,500 daltons. These figures showed good correlation with those published for MTV by Nowinski et al. These results suggest the need for the reexamination of the current tenet that intracytoplasmic particles represent intracellular MTV nucleoprotein cores.
Outgrowth of
Bacillus cereus
Spores Harboring Bacteriophage CP-51 DNA I. Initiation of Bacteriophage Development
Authors: Cohen Amikam , Ben-Ze'Ev Hannah , Yashouv Judith
Published: January 2020

Time of initiation of bacteriophage CP-51 RNA synthesis, inhibition of host DNA synthesis, initiation of CP-51 DNA synthesis, and release of phage was determined in infected
Bacillus cereus
cells and outgrowing spores harboring phage DNA. The development of phage in outgrowing spores is initiated 45 min after induction of spore germination and then proceeds at a rate similar to that observed in infected cells. Although spore RNA synthesis is inhibited by the presence of chloramphenicol or puromycin during germination, these antibiotics do not inhibit initiation of phage DNA transcription in outgrowing spores.
Enzymatic Iodination of Sindbis Virus Proteins
Authors: Sefton Bartholomew M. , Wickus Gary G. , Burge Boyce W.
Published: January 2020

Sindbis virus was iodinated by using the enzyme lactoperoxidase, an iodination technique which labels only surface proteins. By this technique, the two viral glycoproteins are labeled, and the internal viral protein is not. The two glycoproteins are iodinated to strikingly different extents. This difference in susceptibility to iodination apparently is due to the position or conformation of the glycoproteins in the envelope spikes of the virion and not to differing contents of tyrosine, the amino acid substrate of lactoperoxidase. Both viral glycoproteins are iodinated by lactoperoxidase on the surface of Sindbis-infected chicken cells. Here, as in the virion, the glycoproteins are iodinated unequally, with the smaller glycoprotein again being preferentially iodinated. Another virus-specific protein found in large amounts in infected cells, and from which the preferentially iodinated virion glycoprotein is produced by a proteolytic cleavage, is not iodinated by lactoperoxidase. Thus it appears that the viral glycoproteins are present on the cell surface and that the precursor protein is not.
Bacteriophage φ6: a Lipid-Containing Virus of
Pseudomonas phaseolicola
Authors: Vidaver Anne K. , Koski R. K. , Van Etten J. L.
Published: January 2020

The purification and properties of a lipid-containing bacteriophage, φ6, are described. The phage contains a lipid envelope which is probably essential for infection. Infectivity of φ6 was lost in the presence of organic solvents, sodium deoxycholate, and phospholipase A. The fatty acid composition of the phage lipid was similar to that of the
Pseudomonas phaseolicola
host cells. The phage was composed of about 25% lipid, 13% RNA, and 62% protein. The buoyant density of φ6 was 1.27 g/ml in cesium chloride. The morphology of φ6 was unusual; it had a polyhedral head of about 60 nm surrounded by a membranous, compressible envelope which appeared to assume an elongated configuration upon attachment to pili. The adsorption rate constant was 3.3 × 10
−10
ml/min in a semi-synthetic medium and 3.8 × 10
−10
ml/min in a nutrient broth-yeast extract medium. The latent period was shorter in the former medium (80-115 min compared with 120-160 min), and the average burst size was larger (250-400 compared with 125-150). The eclipse period coincided with the latent period.
Specific Monovalent Cation Effects on Modification of Reovirus Infectivity by Chymotrypsin Digestion In Vitro
Authors: Borsa J. , Sargent M. D. , Copps T. P. , Long D. G. , Chapman J. D.
Published: January 2020

Specific monovalent cations control the modification of reovirus infectivity by chymotrypsin. Digestion in K
+
, Rb
+
, or Cs
+
reduces infectivity several logs, whereas in Na
+
or Li
+
digestion markedly enhances infectivity.
Virus-Induced Proteins in Pseudorabies-Infected Cells I. Acid-Extractable Proteins of the Nucleus
Authors: Chantler Janet K. , Stevely William S.
Published: January 2020

Three basic proteins have been identified in chromatin preparations from pseudorabies virus-infected cells. They appear to be virus specified and are similar in size and charge to host histones; one difference however is that they contain tryptophan. All are produced by 3 h postinfection, and two (IP II and III) seem to be arginine rich. Three similar proteins are also found in herpes simplex MP 17-infected cells, and two of these co-electrophorese with two of the pseudorabies proteins. Partially purified preparations of pseudorabies virus contain low amounts of all three proteins.
Complementary RNA Species Isolated from Vesicular Stomatitis (HR Strain) Defective Virions
Authors: Roy Polly , Repik P. , Hefti E. , Bishop D. H. L.
Published: January 2020

The wild-type strain of vesicular stomatitis virus (VSV) contains in its complete virion (VSV-1, B particles) a minus strand RNA. The principle defective particle of the wild-type strain (VSV-111, T particles) contains a shorter minus strand, homologous to part of the VSV-1 genome. Neither virion contains any detectable complementary (plus) strand RNA. In contrast, a preparation of a heat-resistant (HR) strain of VSV containing defective virions was found to contain both plus (21%) and minus strand RNA, present in several distinct size classes. It was found that the RNA in the HR virion preparation was at least 94% single-stranded and principally (96%) in ribonucleoprotein complexes. On extraction the plus and minus strand RNA species partially annealed to give a population of double- and multistranded RNA species. A small amount of RNA polymerase activity was associated with the HR defective virus preparation.
Isolation and Preliminary Characterization of Temperature-Sensitive Mutants of Rhizobiophage C
Authors: Atkins Gregory J.
Published: January 2020

By using mutagenesis induced by
N
-methyl-
N
′-nitro-
N
-nitrosoguanidine, 150 temperature-sensitive mutants of rhizobiophage c were isolated. All were able to form plaques at 14 C but not at 29 C. They were classified into 21 complementation groups. Representative temperature-sensitive mutants from each complementation group were analyzed with regard to gene function. The approximate time of expression of the genes defined by the mutants was measured by temperature-shift experiments. Most genes began to be expressed at 4.0 to 7.5 h after infection at 14 C. Four genes were found which were expressed 2.5 to 3.5 h after infection. Some mutants showed no DNA synthesis at 29 C; some showed a delay in lysis. Some produced apparently normal particles after infection and lysis at 29 C; others produced various types of defective particles. Some mutants showing no DNA synthesis at 29 C nevertheless caused lysis at the normal time together with the production of phage structural components. Representative mutants from each complementation group were mapped by using two-factor crosses. A preliminary genetic map of phage c was constructed from the data.
Isolation and Characterization of Bacteriophage SBX-1 and Its Bacterial Host, Both Endemic in Soybeans
Authors: Dunleavy J. M. , Urs N. V. R.
Published: January 2020

A phage, SBX-1, and its bacterial host,
Xanthomonas
sp. 1, were isolated consistently from roots, internal portions of stems, and leaves of soybean plants. Phage titer in leaves was highly variable. It was very low in seedlings, reached a maximum of 10
4
PFU/ml of sap after 11 weeks of plant growth and again dropped to very low levels. We isolated SBX-1 from plants of all 45 varieties studied, but not consistently from some. Plants of some varieties also carried
Xanthomonas
sp. 2, which was resistant to infection by SBX-1. The SBX-1 particle has a polyhedral head containing DNA of density 1.709. It has an edge-to-edge diameter of 80 nm and a tail length of 112 nm. The tail has a base plate and spikes. This is the first report of the extensive and continuous occurrence of a phage and its host bacterium in plants.
Effects of Actinomycin D and Ultraviolet and Ionizing Radiation on Pichinde Virus
Authors: Carter Michael F. , Murphy Frederick A. , Brunschwig J. Pierre , Noonan Christine , Rawls William E.
Published: January 2020

Actinomycin D (0.05 μg/ml) suppresses the synthesis of ribosomal RNA of baby hamster kidney (BHK21) cells. The production of infectious Pichinde virus was enhanced in the presence of actinomycin D, although the production of virus particles was not substantially different from cultures inoculated in the absence of the drug. By prelabeling BHK21 cells with
3
H-uridine and then allowing the virus to replicate in the presence of actinomycin D, it was possible to show that ribosomal RNA synthesized prior to infection was incorporated into the virion. A single-hit kinetics of inactivation of Pichinde virus was observed with ultraviolet light, suggesting that the virus contains only a single copy of genome per virion. Comparison of the inactivation kinetics by gamma irradiation of Pichinde virus with Sindbis and rubella virus indicated that the radiosensitive genome of Pichinde virus was about 6 × 10
6
to 8 × 10
6
daltons. This value is greater than the 3.2 × 10
6
daltons which was estimated by biochemical analysis. One possible explanation considered is that the ribosomal RNA of host cell origin is functional and accounts for the differences in genome size estimated by the two methods.
Influence of Gene 55 on the Regulation of Synthesis of Some Early Enzymes in Bacteriophage T4-Infected
Escherichia coli
Authors: Bolund Christina
Published: January 2020

In
Escherichia coli
B infected with phage T4 with mutations in gene 55 the shut-off of synthesis of two early enzymes was found to be delayed 10 to 15 min as compared to wild-type T4 infection. The kinetics of early enzyme formation was very similar to that obtained after DNA-negative mutant infection. The transcription of gene 1 (one of the genes coded for early enzymes) ceased at 9 to 12 min after infection whether the gene 55 product was active or not, as determined by the time dependence of fluorouracil rescuability of DNA synthesis in cells infected with a gene 1 amber mutant. The synthesis of the major part of the early RNA species, determined by pulse-labeling with uracil-
5
-
3
H
, was furthermore found to be regulated independently of gene 55. An explanation for the extended early enzyme synthesis in DNA-negative and gene 55 mutant infection is offered: translation of early messengers is restricted after about 12 min in wild-type infection, whereas in cells infected with DNA-negative or gene 55 mutants, i.e., the absence of late protein synthesis, early messengers direct the formation of early enzymes for a longer time.
Assembly and Function of the Lambdoid Bacteriophage Tail: Observations from φ80-Lambda Host-Range Phenotypic Mixing
Authors: Boklage Charles E.
Published: January 2020

The host-range proteins of lambda and φ80, while differing sharply in host-receptor specificity and in sensitivity to phage-killing antiserum, can be assembled into functional phage tail structures of mixed composition.
Terminal Riboadenylate Transferase: a Poly A Polymerase in Purified Vaccinia Virus
Authors: Brown McKay , Dorson J. W. , Bollum F. J.
Published: January 2020

Purified vaccinia virus treated with Triton X-100 catalyzes the incorporation of ATP into an acid-insoluble product. The enzymatic activity responsible for the ATP polymerization is demonstrated to be different from vaccinia RNA polymerase in its preferential use of ATP as substrate and on the basis of heat stability, pH optima, and metal ion requirement. The ATP polymerization reaction is stimulated 10-fold by the addition of rA(pA)
5.
In accordance with our earlier terminology, we call this Mn
2+
-dependent enzyme terminal riboadenylate transferase to distinguish it from Mg
2+
-dependent poly A polymerase.
Penetration into Host Cells of Naked, Partially Injected (Post-FST) DNA of Bacteriophage T5
Authors: Labedan B. , Legault-Demare J.
Published: January 2020

The experiments presented here suggest that the naked post-FST DNA, attached to the bacteria after a centrifugation at 6,000 ×
g
of
Escherichia coli
-T5 complexes arrested at the FST stage, can be injected into the host cell if protein synthesis is allowed. This results from the observation that the production of infectious centers by this naked DNA is sensitive to DNase or moderate shearing treatments. The process of injection seems to be the same as that for DNA normally rolled in an adsorbed capsid.
Isolation of Mutants of Bacteriophage T4 Unable to Induce Thymidine Kinase Activity
Authors: Chace Kenneth V. , Hall Dwight H.
Published: January 2020

New mutants of T4 have been isolated by using a strain of
Escherichia coli
lacking thymidine kinase activity. These T4 mutants, designated
tk
, are able to grow on this
E. coli
strain under light on plates containing 5-bromodeoxyuridine and were all found to be unable to induce thymidine kinase (ATP: thymidine 5′-phosphotransferase, EC 2.7.1.21). All of these
tk
mutants fall into one complementation group which maps just to the right of
rI
on the standard T4 genetic map, far from most other genes coding for enzymes involved in pyrimidine metabolism. The
tk
mutants grow as well as wild-type T4, indicating that thymidine kinase is a non-essential enzyme.
Transforming Ability of a T4 RNA-DNA Copolymer
Authors: McNicol Lore' Anne
Published: January 2020

A coliphage T4-specific RNA-DNA copolymer is genetically competent to transform a marker in gene 43, the DNA polymerase.
Penetration of Host Cell Membranes by Adenovirus 2
Authors: Brown Dennis T. , Burlingham Byron T.
Published: January 2020

Highly purified human adenovirus type 2 directly penetrated the plasma membranes of KB cells. The process of membrane penetration resulted in the appearance of large numbers of adenovirions free in the cytoplasm of the infected cells. The virions underwent a morphological change as they penetrated the cell surface. Penetration of the plasma membranes and the accompanying alteration in virion morphology was dependent on a function associated with the intact cells, because neither event occurred when purified virions were added to isolated cell membranes. Inactivation of the adenovirions with heat or antibodies before inoculation of the cells reduced the infectivity of the virus population and prevented the appearance of virions free in the cytoplasm. The inactivation of the virions did not significantly reduce the number of virus particles which were found in cell vacuoles and pinocytotic vesicles.
RNA-Dependent DNA Polymerase Activity in Preparations of a Mutant of Newcastle Disease Virus Arising from Persistently Infected L Cells
Authors: Furman Phillip A. , Hallum Jules V.
Published: January 2020

RNA-dependent DNA polymerase activity was found in peparations of a mutant of Newcastle disease virus. The enzyme activity was not found in wild-type virus preparations.
RNA Synthesis in Temperature-Sensitive Mutants of Vesicular Stomatitis Virus
Authors: Unger John T. , Reichmann M. E.
Published: January 2020

T-particle-free stocks of temperature-sensitive mutants representing the four Glasgow complementation groups of the Indiana serotype of vesicular stomatitis virus were used to study RNA synthesis at the permissive and nonpermissive temperatures of 31 and 39 C, respectively. Mutants selected from the four Glasgow complementation groups were characterized on the basis of particle and ribonucleoprotein formation. Intracellular RNAs were further characterized by polyacrylamide gel electrophoresis.
ts
G22 (group II) and
ts
G41 (group IV), previously characterized as RNA negative at the nonpermissive temperature, synthesized low levels of RNA which could not be attributed to contaminating levels of revertants. Furthermore, the levels of synthesis could not be reduced by the addition of cycloheximide. These data suggest that
ts
G22 (group II) and
ts
G41 (group IV) contain a thermally stable, virion-encapsidated transcriptase, but fail to amplify RNA synthesis due to a thermally labile function presumably necessary for the synthesis of viral RNA.
ts
G31, a group III mutant, synthesized intracellular RNA at amplified levels at the nonpermissive temperature. Intracellular ribonucleoprotein complexes were isolated in copious amounts; however, no particles corresponding in size to finished virions were observed. These data suggest a thermally labile maturation factor or envelope associated structural protein to be defective in
ts
G31 (group III).
ts
G11 (group 1) showed no detectable RNA synthesis at the nonpermissive temperature. These data suggest
ts
G11 (group I) contains a thermally labile component involved in early transcription. This group may contain a number of mutants defective in different components of the transcription apparatus, which may not complement in vivo because of the physical improbability of subunit exchange between virion particles of the incoming inoculum.
Precursor Protein for Newcastle Disease Virus
Authors: Samson A. C. R. , Fox C. F.
Published: January 2020

The course of viral protein synthesis during infection of chicken embryo fibroblasts with Newcastle disease virus (NDV) L. Kansas has been followed by using sodium dodecyl sulfate polyacrylamide gel electrophoresis. Of the three major virion polypeptide molecular weight classes, I (78,400 daltons), II (53,500 daltons), and III (37,600 daltons), only II, having the same electrophoretic mobility as nucleocapsid polypeptide, appears to be the cleavage product of a precursor polypeptide PII (64,800 daltons) detected in NDV-infected cells after brief labeling with radioactive amino acids. Nucleocapsids were isolated from NDV-infected cells which had been pulse-labeled with radioactive amino acids or pulse-labeled and further incubated with unlabeled amino acids. Gel electrophoretic analysis of proteins derived from nucleocapsids showed that an increase in the period of incubation with unlabeled amino acids resulted in an increase in the amount of radioactivity in nucleocapsid protein. Polypeptide PII was not detected as a transient component of the isolated nucleocapsid fraction. These results are consistent with two interpretations. The product of PII cleavage is (i) nucleocapsid polypeptide, or (ii) a nonvirion or minor envelope polypeptide having the same electrophoretic mobility as nucleocapsid polypeptide.