bluuebunny/crossref_metadata_2025 huggingface dataset:
DNase Specific for Uracil-Containing Bacteriophage DNA
Authors: Tomita F. , Takahashi I.
Published: January 2020

A DNase from
Bacillus subtilis
which specifically hydrolyzes native DNA of phage PBS 1 has been purified and characterized. The mode of action of the enzyme is endonucleolytic, yielding deoxyuridine and oliogonucleotides of various sizes. The primary site of enzymatic attack is deoxyuridylic acid in the DNA. A mild nitrous acid treatment of thymine-containing thymus DNA, which deaminates 30% of the cytosine residues, renders the DNA susceptible to the DNase. Nicked DNA from coli phage T5 and hydroxymethyluracil-containing DNA from phage PBS 15 are not sensitive to this DNase.
Expression of the Major Viral Glycoprotein of Avian Tumor Virus in Cells of chf(+) Chicken Embryos
Authors: Halpern M. S. , Bolognesi D. P. , Friis R. R. , Mason W. S.
Published: January 2020

The expression of gp85, the major viral glycoprotein of avian tumor virus, by certain chicken embryonic cells was studied by the use of sera directed to antigenic determinants of subgroup E viral gp85. As analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of immune precipitates prepared with lysates of cells that had been labeled with [
3
H]glucosamine, chf(+) chicken embryo cells synthesize molecules of gp85 which possess type and probably also group antigenic specificities. Under similar conditions of analysis, no gp85 or antigenically related components could be detected in lysates of chf(−) cells.
Isolation of DNA polymerase gamma from an adenovirus 2 DNA replication complex
Authors: Ito K , Arens M , Green M
Published: January 2020

The major DNA polymerase in a nuclear membrane complex that is capable of synthesizing viral DNA sequences in vitro has been purified about 900-fold from adenovirus 2-infected KB cells. The enzyme was characterized as belonging to the class of mammalian DNA polymerases (DNA polymerase gamma) that can utilize poly(A) with oligo(dT) as template primer.
Anatomy of herpes simplex virus DNA. III. Characterization of defective DNA molecules and biological properties of virus populations containing them
Authors: Frenkel N , Jacob R J , Honess R W , Hayward G S , Locker H , Roizman B
Published: January 2020

We have characterized the virus progeny and its DNA from plaque-purified and undiluted passages of herpes simplex virus 1 in HEp-2 cells. Secifically, (i) infectious virus yields declined progressively in passages 1 through 10 and gradually increased at passages 11 through 14. The yields correlated with PFU/particle ratios. (ii) In cells infected with virus from passages 6 through 10, there was an overproduction of an early viral polypeptide (no. 4) and a delay in the synthesis of late viral proteins. In addition, the virus in these passages interfered with the replication of a nondefective marker virus. Cells infected with passage 14 virus produced normal amounts of polypeptide 4 and, moreover, this virus showed minimal interfering capacity. (iii) In addition to DNA of density 1.726 g/cm-3, which was the sole component present in viral progeny of passage 0, passages 6 through 14 contained one additional species (p 1.732) and in some instances (passages 6 and 10) also DNA of an intermediate buoyant density. The ratio of p 1.732 to p 1.726 DNA increased to a maximum of 4 in passages 6 through 9 and gradually decreased to 1 in passages 10 through 14. (iv) p 1.732 DNA cannot be differentiated from p 1.726 DNA with respect to size; however, it has no Hin III restriction enzyme cleavage sites and yields only predominantly two kinds of fragments with molecular weights of 5.1 x 10-6 and 5.4 x 10-6 upon digestion with EcoRI enzyme. (v) Partial denaturation profiles of purified p 1.732 DNA from passage 14 revealed the presence of two types of tandemly repeated units corresponding roughly in size to the EcoRI fragments and situated in different molecules. (vi) In addition to the two kinds of p 1.732 molecules consisting of tandem repaeat units of different sizes, other evidence for the diversity of defective DNA molecules emerged from comparisons of specific infectivity and interfering capacity of the progeny from various passages. The data suggest that some of the particles with DNA of normal buoyant density (1.726) must also be defective since the capacity to interfere and to produce an excess of polypeptide 4 did not appear to be proportional to the amount of high-buoyant-density defective DNA. The data suggest that defective interfering particles are replaced by defective particles with diminished capacity to interfere and that more than one species of defective DNA molecules evolves on serial preparation of HSV.
Bacteriophage-specific protein synthesis during induction of the defective Bacillus subtilis bacteriophage PBSX
Authors: Thurm P , Garro A J
Published: January 2020

Particles of PBSX, a defective, noninfectious phage which is inducible from strains of Bacillus subtilis 168, contain at least seven structural proteins resolvable by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Five of these proteins are associated with the phage tail and two with the phage head. An eighth protein, which also may be coded for by the PBSX prophage, has been identified in cells derepressed for PBSX replication.
Abortive infection of a rabbit cornea cell line by vesicular stomatitis virus: conversion to productive infection by superinfection with vaccinia virus
Authors: Thacore H R , Youngner J S
Published: January 2020

An abortive infection of a rabbit cornea cell line (RC-60) by vesicular stomatitis virus (VSV), yielding less than 1 PFU/cell, was converted to a productive infection, yielding 1,900 PFU/cell, when cells were superinfected with vaccinia. Studies on the synthesis of VSV-directed RNA in RC-60 cells suggest that the abortive infection by VSV alone may be due in part to (i) a limited production of 40S virion RNA and (ii) a markedly reduced activity of virion-bound transcriptase activity in RC-60 cells compared to the activity in mouse L cells, a permissive host for VSV. No recognizable VSV structures, except a small amount of viral core structures, were produced by the abortive infection. In contrast, double infection of RC-60 cells with VSV and vaccinia in the presence of hydroxyurea resulted in the production of infective B particles of VSV. Although the function supplied by vaccinia responsible for the productive replication of VSV in double infected RC-60 cells has not been identified, metabolic inhibitor studies indicate that continuous vaccinia-dependent RNA synthesis is required for maximal production of infective VSV. The possibility is considered that vaccinia may supply a product or function required for VSV replication which is ordinarily supplied by the host but which is lacking in RC-60 cells.
Regulation of early mRNA synthesis after bacteriophage T4 infection of Escherichia coli
Authors: Linder C H , Fast R
Published: January 2020

Regulation of T4-specific mRNA synthesis was studied during leucine starvation of a leucine-requiring stringent Escherichia coli B strain. This was done by imposing starvation prior to T4 infection and then letting RNA synthesis proceed for different time periods. Rifampin or streptolydigin was added to stop further RNA synthesis, and protein synthesis was restored by addition of leucine. Samples were withdrawn at different times, and the enzyme-forming capacities found that, during conditions which elicit the stringent response in uninfected bacteria, immediate early mRNA is not stringently regulated. This conclusion contradicts the earlier conclusion of others, obtained by measuring incorporation of radioactive uracil; this is explained by the observation of Edlin and Neuhard (1967), confirmed and extended by us to the T4-infected cell, that the incorporation of uracil into RNA of a stringent strain is virtually blocked by amino acid starvation, whereas that of adenine continues at 30 to 50% of the rate seen in the presence of the required amino acid.
DNA synthesis and DNA polymerase activity of herpes simplex virus type 1 temperature-sensitive mutants
Authors: Aron G M , Purifoy D J , Schaffer P A
Published: January 2020

Fifteen temperature-sensitive mutants of herpes simplex virus type 1 were studied with regard to the relationship between their ability to synthesize viral DNA and to induce viral DNA polymerase (DP) activity at permissive (34 C) and nonpermissive (39 C) temperatures. At 34 C, all mutants synthesized viral DNA, while at 39 C four mutants demonstrated a DNA+ phenotype, three were DNA+/-, and eight were DNA-. DNA+ mutants induced levels of DP activity similar to thhose of the wild-type virus at both temperatures, and DNA+/- mutants induced reduced levels of DP activity at 39 C but not at 34 C. Among the DNA- mutants three were DP+, two were DP+/-, and three showed reduced DP activity at 34 C with no DP activity at 39 C. DNA-, DP- mutants induced the synthesis of a temperature-sensitive DP as determined by in vivo studies.
Mapping RNase T1-resistant oligonucleotides of avian tumor virus RNAs: sarcoma-specific oligonucleotides are near the poly(A) end and oligonucleotides common to sarcoma and transformation-defective viruses are at the poly(A) end
Authors: Wang L H , Duesberg P , Beemon K , Vogt P K
Published: January 2020

The large RNase T1-resistant oligonucleotides of the nondefective (nd) Rous sarcoma virus (RSV): Prague RSV of subgroup B (PR-B), PR-C and B77 of subgroup C; of their transformation-defective (td0 deletion mutants: td PR-B, td PR-C, and td B77; and of replication-defective (rd) RSV(-) were completely or partially mapped on the 30 to 40S viral RNAs. The location of a given oligonucleotide relative to the poly(A) terminus of the viral RNAs was directly deduced from the smallest size of the poly(A)-tagged RNA fragment from which it could be isolated. Identification of distinct oligonucleotides was based on their location in the electrophoretic/chromatographic fingerprint pattern and on analysis of their RNase A-resistant fragments. The following results were obtained. (i) The number of large oligonucleotides per poly(A)-tagged ffagment increased with increasing size of the fragment. This implies that the genetic map is linear and that a given RNase T1-resistant oligonucleotides has, relative to the poly(A) end, the same location on all 30 to 40S RNA subunits of a given 60 to 70S viral RNA complex, (ii) Three sarcoma-specific oligonucleotides were identified in the RNAs of Pr-B, PR-C and B77 by comparison with the RNAs of the corresponding td viruses...
RNA-directed DNA polymerase activity of reticuloendotheliosis virus: characterization of the endogenous and exogenous reactions
Authors: Waite M R , Allen P T
Published: January 2020

Reticuloendotheliosis virus (REV) contains an endogenously instructed, RNA-directed DNA polymerase activity. Both the endogenous and exogenous DNA polymerase activities exhibited up to 10-fold greater activity at the optimum concentration of manganous ion (0.025 mM for exogenous; 0.25 mM for endogenous) than at any concentration of magnesium ion. Antiserum to the DNA polymerase of an REV group virus (spleen necrosis virus) inhibited both endogenous and exogenous DNA polymerase activity of REV, whereas antiserum to the Rous sarcoma virus (Rous-associated virus-0) [RSV(RAV-0)]DNA polymerase did not. The DNA product of the endogenous reaction is associated with the high-molecular-weight RNA of REV and anneals with REV RNA but not with RNA from Rous sarcoma virus.
Virion trascriptase activity differences in host range mutants of vesicular stomatitis virus
Authors: Szilágyi J F , Pringle C R
Published: January 2020

Three types of conditional lethal mutant were isolated from wild-type vesicular stomatitis virus, New Jersey serotype, after mutagenization by 5-fluorouracil: (i) conventional temperature-sensitive (ts) mutants, which form plaques at 31 C but not at 39 C; (ii) conventional host range mutants (hr CE), which grow in BHK but not in secondary chicken embryo cells; and (iii) temperature-dependent host range mutants (td CE), which form plaques both at 31 and 39 C on BHK cells but only at 31 C on chicken embryo cells. To determine whether the mutation in hr CE and td CE mutants affected the virion-associated RNA transcriptase, this enzyme was assayed in vitro at 31 and 39 C, and the results were compared with those obtained for the wild-type virus. The RNA trascriptase activity of hr CE mutants did not appear to be affected by the mutation. The td CE mutants fall into two classes: those that synthesized RNA at 39 C similar to the wild-type virus and those that did not. One mutant of the latter category, td CE 3, had heat-sensitive transcriptase regardless of whether it was grown in BHK or chicken embryo cells. A revertant to the wild-type phenotype isolated from this mutant had regained the ability to synthesize RNA at 39 C. These results strongly suggest that a polypeptide that is either the transcriptase itself or part of the transcriptase complex was made temperature sensitive by the mutation in the second class of td CE mutants. The inhibition of the transcriptase activity of the mutant td CE 3 was fully reversible by lowering the temperature of incubation from 39 to 31 C, and both inhibition and reactivation appeared to be instantaneous.
Physical map of the BK virus genome
Authors: Howley P M , Khoury G , Byrne J C , Takemoto K K , Martin M A
Published: January 2020

Two new human papovavirus isolates (JMV and MMV) from the urines of patients with Wiskott-Aldrich syndrome were morphologically and serologically identical to BK virus (BKV). The genomes of these two new isolates were found to be indistinguishable from prototype BKV DNA in a variety of nucleic acid hybridization experiments. Like BKV DNA, JMV and MMV DNAs share approximately 20% of their polynucleotide sequences with simian virus 40 DNA. The genome of JMV was indistinguishable from that of BKV by restriction endonuclease analysis; MMV DNA contained three instead of four R-Hind cleavage sites and one rather than no R-HpaII cleavage sites. Physical maps of the BKV and MMV genomes were constructed using restriction endonucleases, and these maps were oriented to the map of simian virus 40 DNA.
Structure of B77 sarcoma virus RNA: stabilization of RNA after packaging
Authors: Stoltzfus C M , Snyder P N
Published: January 2020

Extracellular maturation of Bratislava 77(B77) sarcoma virus RNA involves a stabilization of linkage between 35S subunits since the Tm of 60 to 70S RNA in the presence of 0.5 M NaCl increases from 56 to 67.5 C as the age of the virus increases. This stabilization process is strongly temperature dependent; the rate at 45 C is increased fourfold over the rate at 37 C. As a result of the instability of the immature RNA, denaturation to subunits occurs at room temperature during phenol extraction. This dissociation can be prevented by increasing the NaCl concentration during the extraction. The data support a model which proposes that RNA subunits of oncornaviruses exist as assembled 60 to 70S RNA even in immature virions but that the linkages between subunits are stabilized as a function of time. These linkages appear to be maintained by nucleotide base pairing rather than by protein. However, isolated RNA does not undergo stabilization, suggesting that some other component of the virion is necessary for the process to occur.
Structural aberrations in T-even bacteriophage. VII. In vitro analysis of the canavanine-mediated inhibition of proteolytic cleavage
Authors: Bolin R W , Cummings D J
Published: January 2020

Canavanine arrests a critical function in head morphogenesis and the potential for forming giant T-even phage particles termed lollipops is induced. Formation of the particles requires the addition of arginine and the restoration of normal functions. We now report on an investigation into the effects of canavanine on both the T4-induced proteolytic activity and on the substrate proteins. Using an in vitro cleavage assay we have shown that the gene 21-dependent proteolytic activity from canavanine-treated extracts is markedly inhibited, whereas the substrate proteins retain a high susceptibility for cleavage. The proteolytic activity in extracts treated with canavanine followed by arginine is readily detectable, and proteins previously synthesized in the presence of canavanine can be cleaved. Protein synthesis is apparently required for the appearance of the proteolytic activity after the canavanine-arginine treatment. Mixing experiments suggest the requirement for a component of the gene 21-dependent proteolytic activity that is not coded for by gene 21.
Surface structure of Uukuniemi virus
Authors: von Bonsdorff C H , Pettersson R
Published: January 2020

Uukuniemi virus, grown in chicken embryo fibroblasts, has been studied by electron microscopy using negative staining, thin sectioning, and freeze-etching techniques. The spherical virus particle measures about 95 nm in diameter. Its envelope consists of a 5-nm thick membrane covered by 8- to 10-nm long surface projections. These are composed of two polypeptides species of about the same size. Both of them can be removed by digestion with the proteolytic enzyme thermolysin except for a small fragment. The enzyme-treated particles are smooth surfaced and extremely deformable. The glycopolypeptides are clustered to form hollow cylindrical morphological units, 10 to 12 nm in diameter, with a 5-nm central cavity. Both negative staining and freeze-etching suggest that these units are penton-hexon clusters arranged in a T = 12, P = 3, icosahedral surface lattice. The membrane to which the surface subunits are attached is probably a lipid bilayer as evidenced by its double-track appearance in thin sections and the tendency of the freeze fracturing to occur within it. The strand-like nucleoprotein appears from thin-sectioning results to be to a large part located in a zone underneath the membrane.
Temperature-sensitive mutants isolated from hamster and canine cell lines persistently infected with Newcastle disease virus
Authors: Youngner J S , Quagliana D O
Published: January 2020

Evidence is presented which confirms that temperature-sensitive (ts) mutants with an RNA- phenotype are spontaneously selected in persistent infection of cell lines with Newcastle disease virus. Persistently infected BHK-21 cells, maintained since 1973, produce no interferon and are completely susceptible to vesicular stomatitis virus. Persistent infection of a canine kidney cell line (MDCK) terminated with destruction of all cells at about 100 days. Even under these conditions, a high proportion (33%) of RNA- temperature-sensitive mutants was present in the virus population 60 days after the infection was initiated.
Method of examining viral RNA metabolism in cells in culture: metabolism of vesicular stomatitis virus RNA
Authors: Wertz G W
Published: January 2020

A method is described for radioactively labeling viral RNA and then quickly halting further incorporation of radioactive precursor into RNA so that the fate of the labeled RNA can be followed. Small complementary RNAs synthesized during vesicular stomatitis virus infection in the presence of cycloheximide do not metabolize to virion length molecules when protein synthesis inhibition is reversed.
Amounts of Epstein-Barr Virus DNA in Somatic Cell Hybrids Between Burkitt Lymphoma-Derived Cell Lines
Authors: Andersson Maria
Published: January 2020

The amounts of Epstein-Barr virus DNA in somatic cell hybrids between human lymphoid cell lines were found to be higher than in the parental cell lines, although the hybrids were not induced to spontaneous virus production.
Restriction Enzyme Digests of Rapidly Renaturing Fragments of Vaccinia Virus DNA
Authors: DeFilippes Frank M.
Published: January 2020

Vaccinia virus DNA fragments that have been denatured by alkali and then neutralized contain a fraction that rapidly reforms duplex structures. The fraction is enriched by fractionating on hydroxyapatite columns and serves as a substrate for digestion by two restriction endonucleases isolated from
Hemophilus parainfluenzae
, Hpa I and HPa II. The patterns obtained by gel electrophoresis of the digested fragments show the presence of three major bands after Hpa I digestion and four major bands after Hpa II digestion. The DNA that is isolated from some of these bands quickly reforms duplex regions after alkaline denaturation. The size of the DNA segments in the major bands has been estimated to be in the range of 0.44 × 10
6
to 3.2 × 10
6
daltons. The fragments which rapidly reform duplex chains after denaturation are sensitive to single-strand-specific nucleases. These results are consistent with a model of vaccinia virus DNA which has a covalent link connecting complementary chains.
Induction of Interferon and Erythropoietic Differentiation in Cells Transformed by Friend Virus
Authors: Swetly P.
Published: January 2020

Two lines of Friend virus (FV)-transformed mouse spleen cells have been analyzed in respect to their interferon production capacity: neither F4 cells, which liberate infectious FV when kept under tissue culture conditions, nor the thymidine kinase-deficient B8 cells, which do not produce significant amounts of FV, release detectable amounts of autogenous interferon into cell supernatants. However, interferon is produced in these cells in amounts comparable to that in L-929 cells when interferon induction is initiated with UV-inactivated Newcastle disease virus. Conversely poly(I) · poly(C), a potent interferon inducer in L-929 cells, proved ineffective in this capacity in F4 or B8 cells. When erythropoietic differentiation is induced in these cells by dimethyl sulfoxide, no autogenous interferon production occurs, but with NDV-induction a four- to fivefold increase of interferon production is observed. A similar elevation of interferon production is achieved during 5-bromodeoxyuridine stimulation of differentiation in the thymidine kinase-deficient B8 cells. The refractiveness against poly(I) · poly(C) displayed in unstimulated cells is not overcome at any stage of differentiation, indicating major differences of Newcastle disease virus and poly(I) · poly(C) induction mechanisms.
Identification of a Precursor Protein to the Major Glycoproteins of Mouse Mammary Tumor Virus
Authors: Dickson C. , Puma J. P. , Nandi S.
Published: January 2020

Mouse mammary tumor virus-producing cultures of mouse mammary tumor cells synthesize a viral-related polypeptide of molecular weight of 73,000 (gp 73) which is rapidly labeled during a short pulse but disappears during the chase concomitantly with the appearance of label in the virion glycoproteins gp 49 and gp 37.5/33.5. The addition of the protein synthesis-inhibitor cycloheximide to the chase medium has little effect on this conversion. Treatment of the proposed precursor with α-chymotrypsin leads to the formation of a polypeptide of molecular weight 49,000, similar to the major virion glycoprotein. A comparison of tryptic digest maps of the glycoproteins involved supports the hypothesis that both the viral glycoproteins gp 49 and gp 37.5/33.5 are derived from gp 73.
Rapid Purification of 70
S
RNA from Media of Cells Producing RNA Tumor Viruses
Authors: Smith R. Guy , Donehower L. , Gallo R. C. , Gillespie D. H.
Published: January 2020

Media from cells producing RNA tumor viruses, when treated with sodium dodecyl sulfate and polyvinyl sulfate, yield 70
S
RNA as the major species binding oligo(dT)-cellulose. The procedure described for purifying 70
S
RNA requires no special equipment and is suitable for rapidly processing large quantities of media or for purifying RNA from commercially available virus, with a 5- to 10-fold higher yield than was obtained using existing methods.
Quantitative Analysis of the Rescue of RNA Sequences by Mammalian Type C Viruses
Authors: Goldberg Robert J. , Levin Reuven , Parks Wade P. , Scolnick Edward M.
Published: January 2020

The specificity and quantitation of the rescue of RNA sequences by mammalian type C viruses has been investigated. Type C viruses can package with specificity only type C viral RNA. Type C viruses do not encapsidate with comparable efficiency either type B viral or cellular globin mRNA. Conversely, a non-type C mammalian retravirus, MP-MV, cannot encapsidate type C RNA. A revertant of Kirsten sarcoma virus (Ki-SV)-transformed nonproducer cells which fails to rescue biologically active Ki-SV after superinfection with helper virus had no detectable intracellular Ki-SV -specific RNA. The results suggest specific mechanisms by which type C viral proteins can package type C viral RNA and provide an approach to classifying RNA of potentially defective endogenous retraviruses as type C in origin.
Bacteriophage T4-induced shut-off of host-specific translation
Authors: Svenson S B , Karlström O H
Published: January 2020

To study the mechanism by which bacteriophage T4 inhibits the synthesis of inducible host enzymes we measured the formation of beta-galactosidase from preformed lac mRNA. Beta-Galactosidase was induced with isopropyl-beta-D-thiogalactopyranoside in the presence of 7-azatryptophan, a tryptophan analogue that is incorporated into proteins and renders the beta-galactosidase formed inactive. The accumulated las mRNA was measured by capacity to form active beta-galactosidase after a chase of the analogue with excess tryptophan. After T4 infection the ability to form beta-galactosidase from the preformed lac mRNA was rapidly lost even when T4 infection took place in the presence of rifampin. This restriction was dependent on the multiplicity of infection. At a multiplicity of infection of 8.6, 90% of the ability to express preformed lac mRNA was lost within 30 s. The kinetics of cessation of beta-galactosidase synthesis after T4 infection indicate that infection blocks initiation of lac mRNA translation.
Rate of virus-specific RNA synthesis in synchronized chicken embryo fibroblasts infected with avian leukosis virus
Authors: Humphries E H , Coffin J M
Published: January 2020

The rate of avian leukosis virus (ALV)-specific RNA synthesis has been examined in bot- uninfected and ALV-infected synchronized chicken embryo fibroblasts. RNA from cells labeled for 2h with [3H]uridine was hybridized with avian myeloblastosis virus poly(dC)-DNA, and the hybridized RNA was analyzed with poly(I)-spephadex chromatography. Approximately 0.5% of the RNA synthesized in ALV-infected cells was detected as virus specific, and no more than a twofold variation in the rate of synthesis was detected at different times in the cell cycle. In synchronized uninfected chicken embryo fibroblasts, approximately 0.03% of the RNA synthesized was detected as virus specific, and no significant variation in the rate of synthesis was observed during the cell cycle. Treatment of ALV-infected chicken embryo fibroblasts with cytosine arabinoside or colchicine was used to block cells at different stages in the cell cycle. The rates of virus-specific RNA synthesis in cells so treated did not differ significantly from the rates in either stationary or unsynchronized virus-infected chicken embryo fibroblasts. These findings support the conclusion that after the initial division of an ALV-infected chicken embryo fibroblast and the initiation of virus RNA synthesis, the rate of virus-specific RNA synthesis is independent of the cell cycle.
Purification and characterization of mouse interferon with novel affinity sorbents
Authors: Davey M W , Sulkowski E , Carter W A
Published: January 2020

Several novel selective sorbents for mouse interferon are described that exploit the hydrophobic property and glycoprotein nature of this molecule. Low-molecular-weight ligands (hydrocarbons) and high-molecular-weight ligands (bovine serum albumin) immobilized on agarose bind selectively mouse L-cell interferon. The high selectivity of binding is due primarily to a hydrophobic effect, although electrostatic forces are also apparently involved. Mouse L-cell interferon binds to immobilized serum albumin and can be completely recovered by raising the ionic strength of the eluant. The specific activity of interferon preparations can be increased 2,000-fold to a value of 3 x 10(8) reference units per mg of protein in a single step with full recovery of the antiviral activity. A selective adsorption, although to a lesser degree, can be also obtained on hydrocarbon-coated agarose (Affi-Gel 202), resulting in 300-fold purification on desorption. The existence of two major components of mouse interferon was revealed upon its chromatography on the following sorbents: (i) bovine serum albumin-agarose, (ii) omega-carboxypentyl-agarose; and (iii) Bandeiraea simplicifolia lectin-agarose. This report thus provides for the first time a means for efficient and clear-cut separation of interferon components, thus enabling their further characterization.
Persistent reovirus infection of CHO cells resulting in virus resistance
Authors: Taber R , Alexander V , Whitford W
Published: January 2020

We obtained a persistently infected line of Chinese hamster ovary cells by selection for resistance to reovirus infection. The cells were persistently infected by a population of viruses that were (i) cytopathic for parental chinese hamster ovary cells and (ii) similar to wild-type reovirus in molecular characteristics. The growth rate, plating efficiency, and morphology of the cells were altered. A large majority of the cells in the population were infected. There was no detectable interferon present in the medium. The cells were relatively resistant to a wide range of viruses.
Characterization of Epstein-Barr virus antigens. I. Biochemical analysis of the complement-fixing soluble antigen and relationship with Epstein-Barr virus-associated nuclear antigen
Authors: Lenoir G , Berthelon M C , Favre M C , de-Thé G
Published: January 2020

The Epstein-Barr virus-soluble (S) antigen extracted from RAJI cells was characterized by sucrose gradient centrifugation, gel filtration, and ion-exchange chromatography. The sedimentation coefficient was estimated to be 8.5S corresponding to a molecular weight of 180,000. The S antigen binds to DEAE-A25 ion exchanger from which it can be eluted with 0.3 M NaCl in Tris buffer (pH 7.2). All fractions which contained complement-fixing S antigen also inhibited the anticomplement immunofluorescence reaction as used to detect the Epstein-Barr virus-associated nuclear antigen. These results are consistent with the hypothesis that the S and Epstein-Barr virus-associated nuclear antigens are either a single antigen or that both activities are present on the same molecule.
Introduction of interrupted secondary structure in supercoiled DNA as a function of superhelix density: consideration of hairpin structures in superhelical DNA
Authors: Woodworth-Gutai M , Lebowitz J
Published: January 2020

PM2 DNA was prepared with different superhelical densities (sigma) in order to examine the relationship betweenn supercoiling and the occurrence of a region(s) of unpaired bases in this DNA. A previous study showed that CH3HgOH reacts with native superhelical PM2 DNA more rapidly than the nicked form II. This evaluation of binding, monitored through the change of sedimentation velocity, was repeated on PM2 DNA I with different superhelical densities. Early binding is detected by an increase in sedimentation velocity and occurs with molecules with sigma' values betwee -0.025 and -0.037. The conversion of form I to form II with the single-strand-specific endonuclease from Neurospora crassa also occurs above a sigma value of -0.025. This data strongly supports the view that supercoiling produces interrupted secondary structure. The question whether the interrupted regions remain single stranded in character or form small intrastrand hairpin regions is considered by examining which model best fits the CH3HgOH- induced sedimentation velocity changes and the standard sedimentation velocity versus the superhelical density curve for the in vitro made DNAs. The hairpin model offers the most satisfactory explanations for all the results of this and previous studies.
Postinfection control by bacteriophage T4 of Escherichia coli recBC nuclease activity
Authors: Behme M T , Lilley G D , Ebisuzaki K
Published: January 2020

Infection by bacteriophage T4 has previously been shown to cause a rapid inhibition of the host recBC DNase, an ATP-dependent DNase that is required for genetic recombination in Escherichia coli. We report here the partial purification of a protein ("T4 rec inhibitor") from extracts of T4-infected cells and some characteristics of the in vitro inhibition reaction with purified inhibitor and recBC nuclease. This inhibitory activity could not be purified from extracts of uninfected E. coli. Both the ATP-dependent exonuclease and DNA-dependent ATPase activities of recBC DNase are inhibited by T4 rec inhibitor. Experiments suggest that the inhibitor interacts with the nuclease in a stoichiometric manner. The biological significance of this inhibition is discussed with respect to control reactions in phage-infected cells.
Proteins solubilized from frog virus 3 particles: effect on transcription
Authors: Aubertin A M , Travo C , Kirn A
Published: January 2020

The treatment of KB cells with viral proteins solubilized from frog virus 3 particles (SVE) induced a rapid shutoff of host RNA synthesis. The RNA polymerase activities of SVE-treated cells were drastically depressed, corresonding, at least for RNA polymerase B, to a decrease in the number of enzyme molecules. In vitro, SVE had no direct effect on RNA polymerases but was capable of binding with calf thymus DNA to form an SVE-DNA complex modifying the template capacity. The effect of SVE on a transcription system consisting of cell lysates would suggest that cytoplasmic factors are necessary for expression of the inhibitory capacity of SVE.
Synethesis and integration of viral DNA in chicken cells at different time after infection with various multiplicities of avian oncornavirus
Authors: Khoury A T , Hanafusa H
Published: January 2020

To see if integration of the provirus resulting from RNA tumor virus infection is limited to specific sites in the cell DNA, the variation in the number of copies of virus-specific DNA produced and integrated in chicken embryo fibroblasts after RAV-2 infection with different multiplicities has been determined at short times, long times, and several transfers after infection. The number of copies of viral DNA in cells was determined by initial hybridization kinetics of single-stranded viral complementary DNA with a moderate excess of cell DNA. The approach took into account the different sizes of cell DNA and complementary DNA in the hybridization mixture. It was found that uninfected chicken embryo fibroblasts have approximately seven copies, part haploid genome of DNA sequences homologous to part of the Rous-association virus 2 (RAV-2) genome. Infection with RAV-2 adds additional copies, and different sequences, of RAV -2- specific DNA. By 13 h postinfection, there are 3 to 10 additional copies per haploid genome. This number can not be increased by increasing the multiplicity of infection, and stays relatively constant up to 20 h postinfection, when some of the additional viral DNA is integrated. Between 20 and 40 h postinfection, the cells accumulated up to 100 copies per haploid genome of viral DNA. Most of these are unintegrated. This number decreases with cell transfer, until cells are left with one to three copies of additional viral DNA sequences per haploid genome, of which most are integrated. The finding that viral infection causes the permanent addition of one to three copies of integrated viral DNA, despite the cells being confronted with up to 100 copies per haploid genome after infection, is consistent with a hypothesis that chicken cells contain a limited number of specific integration sites for the oncornavirus genome.
State of the viral DNA in rat cells transformed by polyoma virus. I. Virus rescue and the presence of nonintergrated viral DNA molecules
Authors: Prasad I , Zouzias D , Basilico C
Published: January 2020

The interaction of polyoma virus with a continuous line of rat cells was studied. Infection of these cells with polyoma did not cause virus multiplication but induced transformation. Transformed cells did not produce infectious virus, but in all clones tested virus was rescuable upon fusion with permissive mouse cells. Transformed rat cells contained, in addition to integrated viral genomes, 20 to 50 copies of nonintegrated viral DNA equivalents per cell (average). "Free" viral DNA molecules were also found in cells transformed by the ts-a and ts-8 polyoma mutants and kept at 33 C. This was not due to a virus carrier state, since the number of nonintegrated viral DNA molecules was found to be unchanged when cells were grown in the presence of antipolyoma serum. Recloning of the transformed cell lines produced subclones, which also contained free viral DNA. Most of these molecules were supercoiled and were found in the muclei of the transformed cells. The nonintegrated viral DNA is infectious. Its specifici infectivity is, however, about 100-fold lower than that of polyoma DNA extracted from productively infected cells, suggesting that these molecules contain a large proportion of defectives.
Inhibition of infectious Rous sarcoma virus production by rifamycin derivative
Authors: Szabo C , Bissell M J , Calvin M
Published: January 2020

A new rifamycin derivative, rifazone-82 (R-82), an inhibitor of viral RNA-dependent DNA polymerase, is selectively toxic to transformed chicken cells in culture. R-82 has now been shown to possess antiviral activity as well. The relatively nontoxic properties of R-82 to nontransformed cells have permitted the execution of experiments examining the effect of a rifamycin derivative on virus reproduction. Addition of low concentrations of R-82 (15 mug/ml) to cultures soon after Rous sarcoma virus infection prevents the spread of infection thoroughout the culture. This inhibition is not dependent on concomitant cellular transformation as identical results were obtained with cells infected with a transformation-defective Rous sarcoma virus. Addition of R-82 to cultures in which all the cells are infected does not substantially affect the yield of physical particles as measured by RNA-dependent DNA polymerase activity and by (3H) uridine incorporation into viral RNA. However, the infectivity of the progeny virus, as measured by focus-forming ability, is decrreased 95 to 99% by R-82 treatment.
Evidence of methylation of B77 avian sarcoma virus genome RNA subunits
Authors: Stoltzfus C M , Dimock K
Published: January 2020

B77 avian sarcoma virus RNA was labeled with (methyl-3H) methionine under conditions that prevent non-methyl incorporation of 3H radioactivity into purine rings. From the determined values for the extent of methylation of 4S RNA isolated from infected chicken embryo cells, it was estimated that 30 to 40S RNA subunits that results from heat denaturation of the 60 to 70S RNA contain approximately 21 methyl groups, of which 14 to 16 are present at internal positions as N6 -methyladenosine residues. In addition, each of the virion RNA subunits appears to contain about two methyl groups in the "capped" 5' -terminal structure m7G(5')ppp(5') gm. These properties are consistent with the hypothesis that the 30 to 40S genome RNA os oncornaviruses also serves an mRNA function in infected cells.
Structural aberrations in group A Staphylococcus bacteriophages
Authors: Ackermann H W , Berthiaume L , Sonea S , Kasatiya S S
Published: January 2020

Six related Staphylococcus phages spontaneously produced various abnormal head and tail structures: (i) giant capsids which were tailed and apparently contained nucleic acid; (ii) regular and irregular smooth polyheads; (iii) heads and polyheads with wavy outlines; (iv) mottled heads and polyheads; (v) abnormally long and short tails; and (vi) "double capsids" connected by a small bridge. Some of these structures are rare, or have not yet been reported. The frequency os specific aberrant particles varied from one phage to another. Length distribution of smooth irregular polyheads and of abnormal tails indicated that these structures assemble at random from protein synthesized in excess. These phages represent an interesting model for genetic and morphogentic studies.
Strain selection during serial passage of Trichoplusia in nuclear polyhedrosis virus
Authors: Potter J N , Faulkner P , MacKinnon E A
Published: January 2020

Two strains of a nuclear polyhedrosis virus (NPV) of Trichoplusia ni were isolated on the basis of plaque morphology. They are designated as MP (having greater than 30 polyhedra per nucleus) and FP (having fewer than 10 polyhedra per nucleus). Serial, undiluted passage of plaque, purified MP nonoccluded. Virus (NOV) in tissue culture led to the production of the FP phenotype detectable at passage 9. With continued serial, undiluted passage, FP became the predominant strain. Comparative growth curves showed that FP NOV are released faster than MP NOV. MP morphology was not observed after 14 serial, undiluted passages of plaque-purified FP. By the plaque neutralization assay, NOV from both strains of virus was neutralized by the homologus and heterologous antisera. The FP phenotype was observed when FP virus was grown in culture at 17, 22, and 27 C. Hence, the FP phenotype was not considered to be the result of temperature-inhibited crystallization of polyhedrin under standard tissue culture conditions. The NOV of both strains killed insects when injected directly into the hemocoele of T. ni larvae. Only MP inclusion bodies were virulent per os. The FP inclusion bodies fed to cabbage looper larvae did not kill, and no infectious agent could be detected in the hemolymph. Electron micrographs of MP polyhedra showed bundles of nucleocapsids of normal length within the polyhedra, whereas FP polyhedra contained heterogeneous, electron-dense material, which could account for their lack of pathogenicity.
Molecular Weight of Bacteriophage PBS2 DNA
Authors: Lauer Gail D. , Klotz Lynn C.
Published: January 2020

The molecular weight of bacteriophage PBS2 DNA has been determined by viscoelastic retardation time experiments to be 1.50 × 10
8
.
Fluorosugars inhibit biological properties of different enveloped viruses
Authors: Schmidt M F , Schwarz R T , Ludwig H
Published: January 2020

Both 2-deoxy-2-fluoro-D-glucose and 2-deoxy-2-fluoro-D-mannose were found to be potent inhibitors of the synthesis of infectious Semliki forest and fowl plague virus in chicken embryo cells and also of pseudorabies virus grown in rabbit kidney cells. It was found that the pseudorabies virus-mediated cell fusion and the synthesis of functional hemagglutinin of fowl plague virus were blocked. In all cases the 2-deoxy-2-fluoro-D-mannose-caused inhibition was stronger than the 2-deoxy-2-fluoro-D-glucose- or 2-deoxy-D-glucose-mediated blocks. Studies on the virus-specified proteins from Semiliki forest virus-infected cells grown in the presence of the inhibitors show that the target of the fluorosugar action, parallel to the well-studied effects of 2-deoxy-D-glucose, is the glycoprotein biosynthesis.
Genetic and physiological studies of abortive infections of hydroxymethyluracil-containing bacteriophages in lysogens of temperate Bacillus subtilis bacteriophage SPO2
Authors: Friedman S O , Hemphill H E
Published: January 2020

Wild-type bacteriophage phie and IS (interference-sensitive) mutants of the related phage SP82G did not productively infect strains of Bacillus subtilis that were lysogenic for temperate phage SPO2. In these abortive infections, the sensitive phages adsorbed to and penetrated the nonpermissive host, phage-directed macromolecular syntheses were initiated, but both viral and bacterial nucleic acid production abruptly stopped about 15 min after addition of the phages. The cessation of RNA and DNA synthesis was preceded or coincident with a reduction in oxygen utilization by the infected cultures. Genetic studies of both phie and SP82G suggest sensitivity to SPO2-mediated abortive infection was controlled by a single gene. A mutant of SPO2, SPO2ehp4-, lysogens of which no longer interfere with the development of SP82GIs, was also isolated. The discovery of this ehp- variant suggests the normal SPO2 prophage synthesized a substance that alters cell physiology in some manner detrimental to SP82GIs development. Since SPO2ehp4- grew on and lysogenized bacteria sensitive to wild-type SPO2, the product of the eph gene was apparently not an essential function of this temperate phage.Overall, these observations exhibit remarkable similarities to the inhibition of T4rII mutants by the product of the rex gene of phage lambda.
Subunit structure of the glycoprotein complex of avian tumor virus
Authors: Leamnson R N , Halpern M S
Published: January 2020

Envelope glycoprotein of avian tumor virus is linked by disulfide bonds in a structure that we have designated VGP to stand for viral glycoprotein. VGP appears to contain one molecule of gp85 and one of gp37. Under nonreducing conditions, VGP is the only glycoprotein component that is stable in the presence of ionic detergent, although in the presence of nonionic detergent two or more VGPs are associated in discrete complexes. The disulfide bonds linking viral glycoprotein are formed before release of virus from infected cells.
RNA synthesis in cells infected with herpes simplex virus. XII. Sequence complexity and properties of RNA differing in extent of adenylation
Authors: Silvertien S , Millette R , Jones P , Roizman B
Published: January 2020

Fractionation of polyadenylated RNA from cells infected with herpes simplex virus by affinity chromatography on columns of poly (U) immobilized on glass-fiber filters yielded three major classes of RNA-containing poly(A) chains with average lengths of 30, 50, and 155 adenylate residues [poly(A)30, poly(A)50, poly(A)155]. In contrast, nitrocellulose membranes bound predominantly a fraction of RNA containing poly(A)155. The distribution of cytoplasmic RNA in the three classes was found to be independent of the labeling interval, ranging from 10 min to 6 h. Cytoplasmic poly(A) RNA consisted mainly (57 to 68%) of the poly(A)155 class; this was also the major class (68%) of polyadenylated RNA found in polyribosomes. Nuclear poly(A) RNA consisted largely (42 to 50%) of poly(A)30 class, whereas high-molecular-weight nuclear RNA sedimenting at greater than 45S contained almost exclusively the poly(A)30 tracts. Hybridization experiments involving unlabeled RNA and labeled viral DNA demonstrated the presence of viral RNA sequences complementary to approximately 40% of viral DNA in all polyadenylated RNA classes. Inasmuch as unfractionated cytoplasmic RNA arises from approximately 40% of the viral DNA, we conclude that most, if not all, viral RNA species present in the cytoplasm are adenylated. In contrast to these results, only a fraction of poly(A)155 RNA, complementary to 21% of viral DNA, bound to nitrocellulose filters. The selective binding of poly(A)155 sequences to nitrocellulose filters might be related to its secondary structure, since transcripts homologous to 40% of viral DNA bind to nitrocellulose membranes, provided the RNA is denatured prior to filtration. The data suggest that poly(A) tracts arise by at least two separate steps. The first involves the appearance of poly(A)30 tracts in the high-molecular-weight nuclear transcripts. The second involves polyadenylation to ply(A)50 and poly(A)155 RNA classes concomitant with processing and transport to the cytoplasm.