bluuebunny/crossref_metadata_2025 huggingface dataset:
Isolation of the dengue virus envelope glycoprotein from membranes of infected cells by concanavalin A affinity chromatography
Authors: Stohlman S A , Eylar O R , Wisseman C L
Published: January 2020

The membranes isolated from type 2 dengue virus-infected BHK-21/15 cells contain three glycosylated virus-specified proteins; one corresponds to the virion envelope glycoprotein, V-3, whereas the other two are nonstructural virus-specified proteins, NV-2 and NV-3. A combination of two nonionic detergents, Nonidet P-40 and Triton X-305, solubilized greater than or equal to 80% of the membrane-bound protein and the majority of the type 2 dengue virus complement-fixing antigens. The soluble material was adsorbed by concanavalin A-Sepharose in the presence of the nonionic detergents, which were subsequently removed by washing with deoxycholate-containing buffer. Finally, the bound glycoprotein was eluted by the addition of alpha-methyl glucopyranoside. V-3 was the only virus-specified protein in the alpha-methyl glucopyranoside eluate. The V-3-containing fraction did not cross-react with antisera against other selected Flaviviruses in the complement fixation tests. The V-3 contained in the isolated fraction differed from the parent membrane-bound V-3 in two interesting, and as yet unexplained, ways: (i) it exhibited hemagglutinating activity similar to that of the infectious virus, but (ii) it did not block the action of neutralizing antibody.
Oligosaccharide moieties of the glycoprotein of vesicular stomatitis virus
Authors: Moyer S A , Tsang J M , Atkinson P H , Summers D F
Published: January 2020

Vesicular stomatitis virus contains a single structural glycoprotein whose carbohydrate sequences are probably specified by the host cell. The glycopeptides derived by Pronase digestion of the glycoprotein of vesicular stomatitis virus grown in HeLa cells have an average molecular weight of 1,800. There are multiple oligosaccharide chains on the vesicular stomatitis virus glycoprotein with protein-carbohydrate linkages that are cleaved only by strong alkali under reducing conditions, suggesting that they contain asparagine and N-acetylglucosamine. The oligosaccharide moieties, in addition, appear to be heterogeneous in sequence on the basis of their mobilities during electrophoresis and their sensitivities to cleavage by an endoglycosidase. The carbohydrate-peptide linkage region of the major class of oligosaccharides of the vesicular stomatitis virus glycoprotein has the proposed sequence: (see article).
N-Tropic variants obtained after co-infection with N- and B-tropic murine leukemia viruses
Authors: Hopkins N , Traktman P , Whalen K
Published: January 2020

Sc-1 cells co-infected with small XC plaque-forming N-tropic and large XC plaque-forming B-tropic murine leukemia viruses produced, in addition to parental types, progeny with the phenotype, large XC plaque morphology, and N-tropism. This phenotype remained stable through end point titration and plaque purification on NIH/3T3 cells and growth on BALB/3T3 cells. These N-tropic viruses (XLP-N virus) grow to unusually high titer and make very large XC plaques.
Influenza virus RNA's in the cytoplasm of chicken embryo cells treated with 3'-deoxyadenosine
Authors: Pridgen C L
Published: January 2020

3'-Deoxyadenosine (75 to 100 mug/ml) permitted analysis of the cytoplasmic influencza virus-specific RNAs synthesized early in the replicative cycle-a phase that has hitherto been obscurred by host cell RNA synthesis. In addition, late in the cycle (6 to 8) complementary virus-specific RNA's were the predominantly labeled species, suggesting that higher concentrations of 3'-deoxyadenosine selectively inhibit influenza viral genome replication.
Regulated transcription of the genomes of defective virions and temperature-sensitive mutants of reovirus
Authors: Spandidos D A , Krystal G , Graham A F
Published: January 2020

Defective reovirus, which lacks the largest (L1) of the 10 double-stranded (ds) RNA genomic segments, attaches to L cells and is uncoated in the same way as reovirus. The defective genome does not replicate in the cells, but it is transcribed. During the first 5 h after infection, three of the genomic segments, M3, S3, and S4, are more frequently transcribed than the remaining six segments. During the succeeding 5 h, there is a transition to a situation in which all nine segments are transcribed at the same relative frequencies. Since the class C ts mutation has been allocated to the L1 segment (Spandidos and Graham, 1975) the transcription of the C mutant genome was investigated in cells infected with it at the nonpermissive temperature, at which the parental genome does not replicate. Genomic segments L1, M3, S3, and S4 are predominantly transcribed at early times, and later all 10 segments are transcribed with the same relative frequencies. Transcription of the defective viral genome and the C mutant genome is therefore regulated in the same way as previously found for wild-type virus (Nonoyama, Millward, and Graham, 1974), and the regulation is independent of genome replication. Apparently the L1 segment function is involved in dsRNA synthesis but not in regulating the early to late transcription. It is suggested that a cellular repressor may be involved in this regulation and that derepression might be effected by one of the early viral gene products. Virion transcriptase activity was studied in vitro with cores prepared by chymotrypsin digestion of purified defective and standard virions. For both genomes the relative frequencies of transcription of the dsRNA segments are inversely proportional to their molecular weights. These results can be accounted for in a model that postulates each segment to be transcribed independently of the other. The same model with certain restrictions can describe the in vivo transcription of the viral genome.
Viral glycoprotein synthesis studies in an established line of Japanese quail embryo cells infected with the Bryan high-titer strain of Rous sarcoma virus
Authors: Halpern M S , Bolognesi D P , Friis R R
Published: January 2020

Although a glycoprotein with an approximate molecular weight of 43,000 is associated with purified virions of the Bryan high-titer strain of Rous sarcoma virus propagated on R(-)Q cells, these virions lack gp85, the major glycoprotein of the avian tumor virus envelope. As measured by immune precipitation with a specific antiserum, gp85 does not accumulate to detectable levels in R(-)Q cells.
Unintegrated viral DNA is synthesized in the cytoplasm of avian sarcoma virus-transformed duck cells by viral DNA polymerase
Authors: Varmus H E , Shank P R
Published: January 2020

We have examined the location, structure, and mechanism of synthesis of unintegrated viral DNA present in fully transformed cultures of avian sarcoma virus-infected duck cells. De novo synthesis of the unintegrated forms several weeks after the initial infection was documented by labeling unintegrated DNA in both strands with 5-bromodeoxyuridine. The unintegrated DNA is synthesized in, and probably confined to, the cytoplasm, and it consists of duplexes of short "plus" strands (ca. 0.5 X 10(6) to 1.0 X 10(6) daltons) and "minus" strands the length of a subunit of the viral genome (ca. 2.5 X 10(6) to 3.0 X 10(6) daltons). The structure of the duplex and the mode of incorporation of density label support the hypothesis that the unintegrated DNA is synthesized from an RNA templated by virus-coded DNA polymerase.
Use of alkaline sucrose gradients in a zonal rotor to detect integrated and unintegrated avian sarcoma virus-specific DNA in cells
Authors: Varmus H E , Heasley S , Linn J , Wheeler K
Published: January 2020

We have attempted to distinguish integrated and unintegrated forms of avian sarcoma virus-specific DNA in cells by sedimentaton through an alkaline sucrose gradient in a slowly reorienting zonal rotor. Results obtained with this procedure are similar to those obtained by the more convenient analysis of networks of high-molecular-weight cell DNA. Most, if not all, viral DNA appears completely integrated into the host cell genome in an avian sarcoma virus-transformed mammalian cell and in normal chicken cells (in which viral DNA is genetically transmitted). Fully transformed duck cells and duck embryo fibroblasts infected for 20 to 72 h contain both integrated and unintegrated viral DNA; up to one copy per cell is integrated within 20 h after infection, and four to eight copies are integrated in fully transformed cells. The amount of unintegrated DNA varies but may comprise over 75% of the viral DNA in acutely infected cells and from 20 to 70% of the viral DNA in fully transformed cells. The unintegrated DNA in either case consists principally of duplexes with "minus" strands the length of a subunit of the viral genome (2.5 X 10(6) to 3 X 10(6) daltons) and relatively short "plus" strands (0.5 X 10(6) to 1.0 X 10(6) daltons).
RNA- temperature-sensitive mutants of vesicular stomatitis virus: L-protein thermosensitivity accounts for transcriptase restriction of group I mutants
Authors: Hunt D M , Emerson S U , Wagner R R
Published: January 2020

In vitro transcriptase activity of three group I temperature-sensitive (ts) mutants of vesicular stomatitis virus restricted at 39 C was restored by L-protein fractions derived from wild-type (wt) vesicular stomatitis virion nucleo-capsids. Soluble NS protein from wt nucleocapsids did not reconstitute restricted transcriptions of the group I RNA-ts mutants. NS protein activity, but not L protein activity, was purified from the group I ts mutants; this NS fraction always displayed the wt phenotype in reconstitution assays. Neither the L nor the NS protein was capable of restoring the defective transcriptive activity of the group IV vesicular stomatitis virus mutant ts W16B.
Cell-free translation of influenza virus mRNA
Authors: Content J
Published: January 2020

Cytoplasmic poly (A)-rich RNA extracted from fowl plague virus-infected cells was found to program efficiently the translation of two major peptides in the wheat germ cell-free system. These peptides have the same electrophoretic mobility, on polyacrylamide gels, as the two major virion proteins M and NP. [35S] methionine tryptic peptide analysis by one-dimensionalthin-layer ionophoresis and finger printing by two-dimensional thin-layer ionophoresis and chromatography show a high degree of similarity between the two in vitro products and the authentic viral proteins M and NP. Although virion RNA is devoid of any poly (A) sequence, it is confirmed here that the viral complementary cytoplasmic RNA contains poly (A) stretches of varying lengths. Intact purified virion was found to promote the synthesis of very low amounts of the same NP and M proteins in this cell-free system. Quantitative aspects of data would indicate that this is due to minute amounts of complementary viral RNA associated with the virion or with the virion RNA itself. In conclusion, it is shown diectly by cell-free translation of authentic viral products that the influenza virion is "negative stranded" (Baltimore, 1971), at least for its two major structural proteins.
Location in bacteriophage lamdba DNA of cleavage sites of the site-specific endonuclease from Bacillus amyloliquefaciens H
Authors: Haggerty D M , Scheif R F
Published: January 2020

The sites in Escherichia coli bacteriophage lambda DNA cleaved by the site-specific endonuclease isolated from Bacillus amyloliquefaciens H (BamI) are found to be at 0.114, 0.466, 0.580, 0.713, and 0.861 lambda units. The sites were located by analysis of the products of digestion of lambda DNA and lambda-ara transducing phage DNA, and verified by double digestion with BamI and EcoRI.
Proteins of Yaba Monkey Tumor Virus I. Structural Proteins
Authors: Fenger T , Rouhandeh H
Published: January 2020

Yaba virus proteins were characterized by polyacrylamide gel electrophoresis. Electrophoresis of Yaba virion (proteins) dissociated by sodium dodecyl sulfate and 2-mercaptoethanol in continuous and discontinuous buffer systems yielded 37 polypeptide species by staining and by counting bands of radioactively labeled polypeptides. The molecular weights of the viral polypeptide species were found to range from 10,000 to 220,000 by comparing the relative distance of migration of viral proteins with proteins of known molecular weights. Two polypeptides were removed from purified virions by nonionic detergent nonidet P -40 treatment, and the amount of one polypeptide was reduced. Purified cores yielded 21 polypeptide species, none of which was labeled with radioactive glucosamine.
Analysis of cytomegalovirus genomes with restriction endonucleases Hin D III and EcoR-1
Authors: Kilpatrick B A , Huang E S , Pagano J S
Published: January 2020

Cleavage of genomes of eleven human, one simian, and one simian-related cytomegalovirus (CMV) isolate by the restriction endonucleases HinD III and EcoR-1 generated reproducible DNA fragments. The size range of CMV DNA fragments as estimated by contour length measurements in comparison with simian virus 40 form II DNA and by coelectrophoresis with EcoR-1 fragments of herpes simplex virus DNA varied between 15 X 10(6) and 0.5 X 10(6) daltons. Comparison of the cleavage products of each isolate in 1% agarose slab gels showed extensive comigration of fragments among the human CMV isolates. In the HinD III digests, three fragment bands comigrated among all human CMV isolates, and six fragments comigrated among most, but not all, human CMV isolates. In the EcoR-1 digests, nine fragment bands comigrated among all human CMV isolates, and five bands comigrated among most, but not all human isolates. Each isolate had a distinctive electrophoretic profile with either HinD III or EcoR-1 digests. No two isolates had identical HinD III or EcoR-1 patterns although some isolates did share more general pattern similarities than others. No clear-cut subgrouping of isolates based on cleavage pattern characteristics could be discerned. Comparison of HinD III and EcoR-1 patterns showed that human isolates differ greatly from nonhuman CMV isolates. HinD III and EcoR-1 digests of each isolate contained both major and minor molar classes of DNA fragments that ranged from about 1 and multiples of 1 M down to about 0.25 M; however, the summed molecular weights for major molar fragments resulting from HinD III or EcoR-1 digests of several isolates closely approximated the molecular weight of 10(8) of the intact genome.
Isolation and preliminary characterization of temperature-sensitive mutants of Newcastle disease virus
Authors: Tsipis J E , Bratt M A
Published: January 2020

Temperature-sensitive (ts) mutants of Newcastle disease virus have been isolated and characterized genetically (complementation), biochemically (RNA synthesis) and biologically (fusion from within and hemadsorption). Fifteen of these mutants have been divided into five complementation groups. Groups A (five mutants) and E (one mutant) are ts for RNA synthesis (RNA-) as well as for the other functions. Group B contains four RNA+ mutants of which one is ts for fusion, one for hemadsorption and two for neither function. Group C contains one RNA+ mutant which is a poor cell fuser. Group D contains two RNA+ mutants which are ts for fusion. In addition, two noncomplementing mutants (group BC) fail to complement both group B and group C mutants while exhibiting complementation with mutants in groups A, D, and E.
Absence of interparental recombination in multiplicity reconstitution from incomplete bacteriophage T4 genomes
Authors: Kozinski A W , Doermann A H , Kozinski P B
Published: January 2020

Interparental recombination between injected T4 DNA molecules is indetectable for incomplete petite phages (carrying a terminally deficient genome and therefore unable to circularize) as well as for genetically complete phages. The nonvialbe petite phages can individually replicate their DNA repeatedly, and they aso undergo multiplicity reconstitution, producing complete phages, provided that a host bacterium is infected by several petite particles that carry genetically complementary segments of DNA. The formation of complete phages in multiplicity reconstitution must be due to recombination among incomplete progeny fragments, i.e., partial replicas of the T4 genomes. It evidently does not result from interparental recombination. To test for interparental recombination, light bacteria (containing no bromouracil) were simultaneously infected in light medium with light radioactive phage in minority (usually less than one per cell) and heavy (bromouracil-labeled) phage in majority (usually about nine per cell). Any interparental recombination should, under these circumstances of infection, head to movement of the radioactive label of the minority light phage DNA to a position of higher density. That possibility was not observed.
Processing of mengovirus precursor polypeptides in the presence of zinc ions and sulfhydryl compounds
Authors: Nakai K , Lucas-Lenard J
Published: January 2020

The effect of zinc ions on the post-translational cleavage of mengovirus polypeptides has been examined. The cleavage of the "A" precursor, which gives rise to the capsid proteins, was the most sensitive at concentrations of zinc chloride from 0.1 to 1.0 mM. Beta-mercaptoethanol and dithiothreitol antagonized the zinc-promoted inhibtion of clevage. Our results indicate that zinc ions interfere with the proper folding of the nascent polypeptide precursor rather than inhibit the proteases responsible for the cleavages. Thus, proper folding of mengovirus polypeptide "A" appears to be necessary for subsequent processing by proteases.
Novel replicative properties of a capsid mutant of bacteriophage phi chi 174
Authors: Vito C C , Dowell C E
Published: January 2020

A capsid mutant of bacteriophage phi chi 174 demonstrates altered requirements for the conversion of viral single-stranded DNA to double-stranded replicative form DNA. In the presence of puromycin at 42 C, wild-type phi chi 174 is unable to complete this replicative event, whereas phi chi ahb is able to do so. Furthermore, in contrast to wild-type phi chi 174, formation of phi chi ahb parental replicative form DNA is sensitive to rifampin under certain experimental conditions. These data suggest that the mutant capsid proteins of phi chi ahb influence the biosynthesis of phi chi ahb complementary strand DNA.
Temperature-sensitive mutants of vesicular stomatitis virus are conditionally defective particles that interfere with and are rescued by wild-type virus
Authors: Youngner J S , Quagliana D O
Published: January 2020

Temperature-sensitive (ts) mutants of vesicular stomatitis virus belonging to complementation groups I, II and IV inhibited the replication of wild-type vesicular stomatitis virus when mixed infections were carried out in BHK21 cells at 32, 37, and 39.5 C. The group IV mutant (ts G 41) was most effective in this regard; wild-type virus yields were inhibited almost 1,000-fold in mixed infections with this mutant at 32 C. In the case of group I and II mutants, inhibition of wild-type virus replication at 37 and 39.5 C was accompanied by an enhancement (up to 15,000-fold) of the yields of the coinfecting ts mutant. The yields of the group IV mutant (ts G 41) were not enhanced by mixed infections with wild-type virus at any temperature, although this mutant inhibited wild-type virus replication at all temperatures. The dominance of the replication of ts mutants at 37 C provides a rationale for the selection and maintenance of ts virus in persistently infected cells.
Temperature-sensitive mutants of reovirus type 3: evidence for aberrant mu 1 and mu 2 polypeptide species
Authors: Cross R K , Fields B N
Published: January 2020

An analysis of reovirus-specific polypeptides in cells infected with temperature-sensitive mutants under permissive and nonpermissive conditions revealed the presence of (i) all the known viral polypeptides and (ii) aberrant migration of the mu 1 and mu 2 polypeptides in four groups of mutants.
Mechanisms of infection with Epstein-Barr virus. I. Viral DNA replication and formation of noninfectious virus particles in superinfected Raji cells
Authors: Yajima Y , Nonoyama M
Published: January 2020

Human lymphoblastoid Raji cells, which do not produce virus, supported replication of Epstein-Barr virus (EBV) upon superinfection. Early antigen, viral capsid antigen, and virions were produced in Raji cells superinfected with EBV. Viral DNA replicated under complete inhibition of host cell DNA synthesis to the extent that a few micrograms of EBV DNA were recovered from 107 superinfected Raji cells, corresponding to 5,000 viral genomes/cell. Homology of the synthesized viral DNA to parental EBV DNA was more than 90%. Virions produced by the Raji cells contained a 55S DNA but failed to induce early antigen, viral capsid antigen, and viral DNA synthesis after a second superinfection of Raji cells.
Role of temperature-sensitive mutants in persistent infections initiated with vesicular stomatitis virus
Authors: Youngner J S , Dubovi E J , Quagliana D O , Kelly M , Preble O T
Published: January 2020

Noncytocidal persistent infections at 37 C of mouse L cells (Lvsv) with infective B particles of vesicular stomatitis virus (VSV) could be established only in the presence of large numbers of defective interfering (DI) particles. Under these conditions, there was a rapid spontaneous selection of temperature-sensitive (ts) virus. At 10 days there was an increase to 17.8% in the frequency of ts clones in the virus population; by 17 days this frequency had reached 85.2%, and by 63 days 100% of the clones isolated were ts at 39.5 C, the nonpermissive temperature used. All 34 of the clones isolated from the 84-day fluid had an RNA-phenotype, and 8 clones that were tested all belonged to VSV complementation group I. When tested by an interference assay, Lvsv fluids did not contain significant numbers of DI particles (less than 1 DI/PFU). Furthermore, persistent infection of L cells at 37 C could be initiated under conditions in which few, if any, DI particles were present by using low input multiplicities (10(-4) and 10(-5) of a clonal isolate of an RNA-group I mutant obtained from Lvsv cells. On the basis of these and other results, a mechanism is proposed to explain the role of ts mutants in both the establishment and maintenance of the persistently infected state.
Induction of DNA polymerase in polyoma virus-infected mouse cells requires transcription and translation
Authors: Wintersberger E , Wintersberger U
Published: January 2020

The induction of DNA polymerase activity and of DNA synthesis in polyoma virus-infected mouse kidney cells is inhibited by actinomycin D and cycloheximide, even in cells that are already T-antigen positive. This indicates that the induction of the DNA-synthesizing apparatus requires transcription and translation. The increase in cellular DNA polymerase activity and in the DNA synthesizing capacity follows the appearance of T-antigen only after a characteristic lag period of several hours.
Encephalomyocarditis virus RNA: variations in polyadenylic acid content and biological activity
Authors: Hruby D E , Roberts W K
Published: January 2020

Encephalomyocarditis (EMC) viral RNA was isolated from purified virus grown in Ehrlich ascites tumor cells. The viral RNA was found to contain polyadenylic acid [poly(A)] regions that were very heterogeneous in length. Chromatography of the EMC viral RNA on oligo(dT)-cellulose columns separated the RNA into three distinct fractions (peaks 1 to 3). Approximately 20% of the EMC viral RNA appeared as peak 1, 40% as peak 2, and 40% as peak 3. The RNA in each fraction appeared to be intact as shown by co-sedimentation with 35S unfractionated EMC viral RNA in SDS-sucrose density gradients. Approximately 95 to 100% of peaks 1 and 3, and 60 to 70% of peak 2, reappeared at the same elution position after rechromatography on oligo(dT)-cellulose. The RNA in peak 1 contained poly(A) with an average length of 16 nucleotides, peak 2 contained poly(A) with an average of 26 nucleotides, and peak 3 contained an average of 74 nucleotides in its poly(A) region. The distribution in the three fractions, as well as the average length of the poly(A) moieties, was relatively unaffected by changes in the cell suspension medium used during infection. Finally, each of the three viral RNA fractions was assayed for biological activity using an infectious RNA assay on L-cell monolayers. Infectivity of the viral RNA was found to increase with poly(A) length, with peak 3 viral RNA being approximately 10 times more infectious than peak 1 viral RNA.
Size of murine RNA tumor virus-specific nuclear RNA molecules
Authors: Haseltine W A , Baltimore D
Published: January 2020

About 1% of the total RNA of cell lines producing murine leukemia virus is virus-specific RNA. About one-third of the virus-specific RNA is located within the nucleus. The size distribution of virus-specific RNA was determined before and after denaturation. Before denaturation, virus-specific RNA sequences sedimented as a heterogeneous population of RNA molecules, some of which sedimented very rapidly. After denaturation, most of the virus-specific RNA had a sedimentation coefficient of 35S or lower, but a small fraction of the nuclear virus-specific RNA sedimented more rapidly than 35S RNA even after denaturation.
Recombination between a temperature-sensitive mutant and a deletion mutant of Rous sarcoma virus
Authors: Kawai S , Hanafusa H
Published: January 2020

Cells doubly infected with two mutants of the Schmidt-Ruppin strain of Rous sarcoma virus (RSV), ts68, which is temperature sensitive for cell transformation (srcts), and a deletion mutant, N8, which is deficient in the envelope glycoprotein (env-), produced a recombinant which carried the defects of both parents. The frequency of formation of such a recombinant was exceptionally high and made up 45 to 55% of the progeny carrying the srcts marker. By contrast, the reciprocal recombinant, which is wild type in transformation (srcts) and contains the subgroup A envelope glycoprotein (envA), was almost undetectable. This remarkable difference in the frequency of the formation of the two possible recombinants suggests that a unique mechanism may be involved in the genetic interaction of the two virus genomes, one of which has a large deletion. When an RNA-dependent DNA polymerase-negative variant of the N8 (N8alpha) was crinants also became deficient in the polymerase. Cells infected by the srctsenv- recombinant were morphologically normal at the nonpermissive temperature (41 degrees C) and susceptible to all subgroups of RSV. The rate by which the wild-type RSV transformed the recombinant-preinfected cells was indistinguishable from that of transformation of uninfected chicken cells by the same wild-type virus. This indicates that no detectable interference exists at postpenetration stages between the preinfected and superinfecting virus genomes and confirms that the expression of the transformed state is dominant over the suppressed state.
Gene A product of phi X174 is required for site-specific endonucleolytic cleavage during single-stranded DNA synthesis in vivo
Authors: Fujisawa H , Hayashi M
Published: January 2020

A functional gene A product of phi X174 was found to be required at the stage of single-stranded DNA synthesis. A precursor complex that synthesizes single-stranded DNA (50S complex [Fujisawa and Hayashi, 1976]) was isolated from cells infected with wild-type or with temperature-sensitive gene A mutant phage. Proper cleavage of the single-stranded viral DNA did not occur in cells infected with the temperature-sensitive gene A mutant under restrictive conditions. This resulted in (i) accumulation of linear viral DNA molecules of 2 units in length in the 50S complex and (ii) cessation of elongation of viral-strand DNA after one complete cycle of single-stranded DNA synthesis.
Nature of the molecular heterogeneity of human leukocyte interferon
Authors: Chen J K , Jankowski W J , O'Malley J A , Sulkowski E , Carter W A
Published: January 2020

The existence of two components of human leukocyte interferon has been recently reported. In the present study, the nature of this molecular heterogeneity was explored by affinity chromatography on immobilized micro- and macroligands, ion-exchange chromatography, and molecular sieving. Chromatography on a series of alkyl-agarose adsorbents shows, for the first time, the intrinsic hydrophobicity of human leukocyte interferon. Additionally, the separation of two interferon components is achieved by use of the alkyl-agarose as well as by the omega-aminoalkyl-agarose adsorbents. Clear-cut separation of the two components was also achieved by chromatography on BSA-CH-Sepharose and on DEAE-Bio Gel A. An important feature of these separations is that they do not require the use of denaturing conditions. The molecular weights of the leukocyte interferon components, as determined on Sephadex G-75, are quite similar or identical, approximately 26,000. Thus, the molecular heterogeneity of human leukocyte interferon can be attributed, at least in part, to differences in the hydrophobicity and ionic properties of its two components.
Mutator mutations in bacteriophage T4 gene 32 (DNA unwinding protein)
Authors: Koch R E , McGaw M K , Drake J W
Published: January 2020

Bacteriophage T4 gene 32 encodes a DNA unwinding protein required for DNA replication, repair, and recombination. Gene 32 temperature-sensitive mutations enhance virtually all base pair substitution mutation rates.
RNA polymerase activity in purified virions of avian reticuloendotheliosis viruses
Authors: Mizutani S , Temin H M
Published: January 2020

An RNA polymerase activity that synthesizes a U-rich RNA hydrogen bonded to a large viral RNA molecule was found in the cores of virions of avian reticuloendotheliosis viruses (REV). The RNA polymerase activity was separable from the DNA polymerase activity of REV virions. The 5'-terminus of the newly synthesized RNA was A. In addition, a tRNA nucleotidyl transferase activity, which added -CpCpA ends to tRNA, appears to be present in the REV virions.
Early events in polyoma virus infection: attachment, penetration, and nuclear entry
Authors: Mackay R L , Consigli R A
Published: January 2020

The plaque-assay technique was used as a tool to determine the optimal conditions for adsorption of polyoma virions to host cells. Using these optimal conditions of adsorption, an electron microscopy study of the early events of infection was performed. By electron microscopy and autoradiography, it was demonstrated that both the viral coat proteins and DNA arrive simultaneously in the nucleus as early as 15 min postinfection. When horseradish peroxidase-labeled virions, pseudovirions, and capsids were used to infect cells, only the particles with nucleic acid or a factor(s) associated with the nucleic acid, i.e., histones, appeared to enter the nucleus. Moreover, when virions were used to infect either permissive or nonpermissive cells, identical early events of viral infection, i.e., adsorption, penetration, and nuclear transport, were observed, suggesting that these early events of infection are a property of the virion and not the host cell.
Radioisotopic labeling of human papovavirus (BK) by iodination and reductive alkylation
Authors: Wright P J , di Mayorca G
Published: January 2020

Purified virions of the GS strain of the BK group of human papovaviruses were labeled with 125I using chloramine T or lactoperoxidase or with tritium using sodium borohydride. All viral polypeptides were labeled. Tryptic digests of iodinated VP1 were analyzed.
Control of synthesis of mRNA's for T4 bacteriophage-specific dihydrofolate reductase and deoxycytidylate hydroxymethylase
Authors: Witmer H , Baros A , Ende D , Dosmar M
Published: January 2020

A 30 degrees C, functional messengers for dCMP hydroxymethylase first appeared 3 to 6 min postinfection and reached their maximum levels at 12 min. Chloramphenicol, added before the phage, reduced the rate of mRNA accumulation. When the antibiotic was added 6 min postinfection, mRNA levels increased at their normal rate but there was no obvious repression of messenger accumulation. Delaying the addition of drug until 8 or 12 min had progressively less effect on the pattern of hydroxymethylase mRNA metabolism. When chloramphenicol was present from preinfection times or from 6 min postinfection, all hydroxymethylase mRNA's synthesized were stable; at later times, however, the ability of the drug to stabilize mRNA decreased with its ability to delay the turnoff of mRNA production. An overaccumulation of hydroxymethylase mRNA was also seen when phage-specific DNA synthesis was inhibited either by mutational lesion in an essential viral gene or by 5-fluorodeoxyuridine. By min 20 of a DNA-negative program, hydroxymethylase mRNA synthesis was repressed to the point where it no longer compensated for decay. However, a finite level of hydroxymethylase mRNA synthesis was maintained at later times of a DNA-negative infection. Such results indicate that replication of the phage chromosome is necessary but not sufficient for a complete turnoff of hydroxymethylase mRNA production. Functions controlled by the maturation-defective proteins (the products of genes 55 and 33) played only a minor role in the regulation of hydroxymethylase mRNA, metabolism. Thus, we favor the hypothesis that a complete turnoff of hydroxymethylase messenger production requires one or more new proteins as well as an interval of DNA replication. The absence of DNA synthesis had no particular effect upon dihydrofolate reductase messenger production. The preinfection addition of chloramphenicol likewise had little effect on dihydrofolate reductase messenger metabolism. These latter data imply that prior synthesis of a phage-coded protein synthesis may not be required for the turnoff of reductase messenger production.
Enzymatic action of coliphage omega8 and its possible role in infection
Authors: Prehm P , Jann K
Published: January 2020

The receptor of coliphage omega8 is the O-specific mannan of Escherichia coli O8 in which the trisaccharide alpha-mannosyl-1,2-alpha-mannosyl-1,2-mannose is joined through alpha-mannosyl-1,3-linkages. Coliphage omega8 produces an endo-alpha-1,3-mannosidase which destroys the receptor, liberating a series of oligosaccharides (repeating trisaccharide and multiples). The enzyme is an integral part of the phage particles and also occurs in a free form in the lysates. Phage particles hydrolyze alpha-1,3-mannosyl linkages in the lipopolysaccharide, the polysaccharide (mannan) moiety, and higher oligosaccharides with an efficiency decreasing in this order. No transmannosylation could be detected. Phage particles also degrade the receptor mannan on whole bacteria, as determined with 14C-labeled E. coli O8. The values of Km and Vmax were determined with omega8 particles and free enzymes using native lipopolysaccharide and its triethylammonium salt. The latter, which was obtained after electrodialysis, has a micellar weight of 2.5 X 10(5), whereas the native lipopolysaccharide forms supermicelles with micellar weights of several millions. With coliphage omega8 as enzyme and supermicellar lipopolysaccharide as substrate Km=5 X 10(-8) M was obtained. This, together with the fact that omega8 attaches irreversibly to E. coli O8, was used in proposing a hypothesis for the possible role of the enzyme in the first steps of infection with coliphage omega8.
Methylation pattern of genomic RNA from Moloney murine leukemia virus
Authors: Bondurant M , Hashimoto S , Green M
Published: January 2020

32P- and methyl-3H-labeled 70S Moloney murine leukemia virus RNA was purified from virions produced in Moloney murine leukemia virus-infected mouse embryo cells. Primer-free RNA subunits obtained by heat treatment and zonal centrifugation were digested with RNase T2, and methylated oligonucleotides were chromatographed on DEAE-Sephadex in 7 M urea. Approximately one molecule of RNase T2-stable oligonucleotide (-5 charge) was isolated per subunit. Structural analysis indicated that the sequence of the oligonucleotide is m7GpppGmpCp. Analysis of the mononucleotide fraction isolated by DEAE-Sephadex chromatography of the RNase T2 digest identified 15 to 23 internal N6-methyladenylic acid molecules per subunit.
Selection of Morphologically Normal Cell Lines from Polyoma-transformed BHK21/13 Hamster Fibroblasts
Authors: Marin G. , Littlefield J. W.
Published: January 2020

A selective method was devised for the isolation of “revertants” from polyoma-transformed sublines derived from BHK21/13 Syrian hamster fibroblasts. A hybrid, polyploid subline was obtained by growing together, in mixed culture in the presence of aminopterin, two variant BHK21/13 sublines lacking either inosinic acid pyrophosphorylase or thymidine kinase. Whereas these variant sublines were resistant to 6-thioguanine or to 5-bromodeoxyuridine, the hybrid had regained sensitivity to both analogues. By plating a polyoma-transformed subline derived from this hybrid in the presence of 6-thioguanine, resistant clones were obtained with a frequency of about 10
−4
. All of these surviving clones had a reduced chromosome complement and some of them had regained a normal phenotype.
Chromosomal and Autoradiographic Studies of Cells Infected with Herpes Simplex Virus
Authors: Waubke Rainer , zur Hausen Harald , Henle Werner
Published: January 2020

The induction of chromosomal aberrations by herpes simplex virus (HSV) and the interaction between viral deoxyribonucleic acid (DNA) and chromosomes have been studied (i) by infection of the BHK-21 line of hamster kidney cells at multiplicities ranging from 0.5 to 100 followed by 1-hr pulses of
3
H-thymidine preceding preparation at varying intervals of metaphases and autoradiography, and (ii) by use of
3
H-thymidine-labeled HSV for infection, chromosomal, and autoradiographic analyses at intervals thereafter. The results revealed that (i) chromosomal lesions develop prior to, and thus are independent of, viral DNA synthesis; (ii) HSV is capable of replicating in cells during the late G-2 period or in metaphase; (iii) most of the viral DNA remains unassociated with chromosomes and is not detectable at sites of chromosomal lesions; (iv) the capacity of the virus to cause chromosomal aberrations is four times less sensitive to inactivation by ultraviolet (UV) irradiation than its infectious property; and (v) after large doses of UV, invasion of the nuclei by the irradiated virus is reduced. These observations indicate that the chromosomal lesions induced by HSV result most likely from action of an early enzyme under control of the viral genome. This explanation is proposed also for the effects of adenovirus type 12 on chromosomes.
Virus-Receptor Interaction in an Adenovirus System
Authors: Philipson Lennart , Lonberg-Holm Karl , Pettersson Ulf
Published: January 2020

HeLa or KB cells each contain around 10
4
receptor sites for adenovirus type 2. These are inactivated by treatment of live cells with subtilisin. The receptor activity of the enzyme-treated cells is regained after 4 to 8 hr of incubation in complete medium. A technique that utilizes the difference in buoyant density between free virus and virus-receptor complex was developed to demonstrate receptor activity. Cellular fractionation revealed that receptors were confined mainly to the plasma membrane fraction and that negligible receptor activity could be demonstrated in enzyme-treated cells. Subtilisin probably did not penetrate the cell membrane; thus, the receptors are limited to the cell surface. Purified fiber of the virion completely prevents attachment of adenovirus types 2 and 5 to receptor sites at a ratio of 10
5
protein molecules per cell. Adsorption studies indicate that 10
5
to 10
6
receptor sites are available for the structural protein. The fiber does not affect attachment of poliovirus type 1.
Evidence for a New Endonuclease Synthesized by λ Bacteriophage
Authors: Shuster Robert C. , Weissbach Arthur
Published: January 2020

Infection of nonlysogenic
Escherichia coli
CR34(S) (Thy
−
) with bacteriophage λ C
I
857 resulted in the formation of twisted circular double-stranded phage deoxyribonucleic acid (DNA; species I). When such infected bacteria were incubated in the absence of thymine, there was a significant decrease in the amount of species I DNA after 60 min of incubation. A similar loss of species I λ DNA during incubation in a thymine-deficient medium was also observed after infection of the endonuclease I-deficient strain,
E. coli
1100(S) (Thy
−
). This destruction of twisted, circular λ DNA in thymine-deprived cells did not occur in the presence of chloramphenicol nor in lysogenic
E. coli
CR34 carrying a noninducible λ prophage. It is therefore concluded that the endonuclease which attacks this circular configuration of λ DNA is newly synthesized after infection and is directed by the phage chromosome.
Ultrastructure of the Surfaces of Cells Infected with Avian Leukosis-Sarcoma Viruses
Authors: Morgan Herbert R.
Published: January 2020

When stained with ruthenium red (RR), chick embryo cells infected with various strains of Rous sarcoma virus (RSV) and with avian leukosis viruses RAV-1 and RAV-3 showed an increase in the layer of acid mucopolysaccharides (AMPS) at their surfaces as compared with uninfected cells. This increase was most prominent in cells infected with the Fujinami strain of RSV. The layer was resistant to digestion with neuraminidase or trypsin but was readily removed by exposure to hyaluronidase. The thickness of this AMPS layer was not correlated with the varying degree of loss of contact inhibition exhibited by cells infected with the different strains of virus. The staining of the cell envelope with a solution of phosphotungstic and chromic acids (PTA-CR) suggested the presence of glycoproteins. The outer surface of the virions showed the same staining as the cell surface with RR and PTA-CR, and the budding virus particle was seen to incorporate the RR layer of the cell into its structure. The RR layers of cells and virions appeared to fuse, as did those between virus particles, suggesting that these layers play a role in the aggregation of virus particles and in their adherence to the surface of the cell.
Defectiveness of Interferon Production and of Rubella Virus Interference in a Line of African Green Monkey Kidney Cells (Vero)
Authors: Desmyter Jan , Melnick Joseph L. , Rawls William E.
Published: January 2020

Vero cells, a line of African green monkey kidney cells, failed to produce interferon when infected with Newcastle disease, Sendai, Sindbis, and rubella viruses, although the cells were sensitive to interferon. Further, infection of Vero cells with rubella virus did not result in interference with the replication of echovirus 11, Newcastle disease virus, or vesicular stomatitis virus, even in cultures where virtually every cell was infected with rubella virus. Under the same conditions, BSC-1 cells and other cells of primate origin produced interferon and showed rubella virus interference. The results indicate that the presence of rubella virus in the cell does not in itself exclude multiplication of other viruses and that rubella virus interference appears to be linked to the capability of the cell to produce interferon.
Efficiency of Nitrous Acid as An Inactivating and Mutagenic Agent of Intact Tobacco Mosaic Virus and Its Isolated Nucleic Acid
Authors: Sehgal O. P. , Krause G. F.
Published: January 2020

When tobacco mosaic virus (TMV) and its isolated nucleic acid (TMV-RNA) were treated with nitrous acid, the nucleic acid was inactivated six times faster than the intact virus. Inactivation of both the infectious entities was exponential with treatment time to 0.1% level of survival. Eight different mutant phenotypes were scored after inactivation of TMV and TMV-RNA to 50, 10, 1.0, and 0.1% survival levels. Significantly more mutants in relation to unaltered isolates were induced at all levels of survival upon nitrous acid treatment of TMV than of TMV-RNA. Furthermore, the proportion of two specific mutant phenotypes was significantly greater in treated TMV than in treated TMV-RNA. No qualitative differences, however, were observed between the mutational spectra of nitrous acid-treated TMV and TMV-RNA. These results indicate that, in the intact virus, the viral capsid protects some of the sites involved in lethality; thus, proportionately more mutants are induced on nitrous acid treatment of TMV versus TMV-RNA.
Second Locus of Bacteriophage P22 Necessary for the Maintenance of Lysogeny
Authors: Gough Michael
Published: January 2020

A temperature-sensitive allele of a locus of phage P22, known to be involved in establishment of lysogeny, has been isolated. This mutant, P22
ts mnt
, forms stable lysogens at 30 C which are induced by heating to 43 C. This shows that this locus is involved in the maintenance of lysogeny. The
ts mnt
locus is about 18 recombination units away from the
c
region. The wild allele,
mnt
+
, is dominant over
mnt
and is responsible for a cytoplasmically diffusible product.
Early Abortive Lysis by Phage BF23 in
Escherichia coli
K-12 Carrying the Colicin Ib Factor
Authors: Nisioka Taizo , Ozeki Haruo
Published: January 2020

Growth of phage BF23 was restricted in
Escherichia coli
K-12 strains carrying a colicin I factor (ColIb); most infected cells lysed early without producing progeny phages. Either addition of chloramphenicol before phage infection or ultraviolet irradiation of phage prevented early abortive lysis, an indication that certain phage functions are required for this phenomenon. Very little or no phage-induced lysozyme was synthesized in the infected ColI
+
cells. This result suggests that early abortive lysis was not due to the lysozyme action. A small fraction (0.05) of BF23-infected ColI
+
cells showed normal phage growth. This “escaped growth” may reflect the physiological state of the host bacteria rather than the heterogeneity of the infecting phage. Host-controlled modification was not observed. A phage mutant, BF23hI, able to grow on ColI
+
cells, was isolated and was characterized to be recessive to the wild-type BF23 in its ability to undergo early abortive lysis. Among the T series phages, T5 induced early abortive lysis, and growth of T5 was restricted upon infection to ColI
+
cells. These results and the other observations, including the occurrence of phenotypic mixing between BF23 and T5, suggest that these two phages are related to each other even though the receptor sites for BF23 and T5 are apparently different.
Effect of Infection with Ribonucleic Acid Bacteriophage R23 on the Inducible Synthesis of β-Galactosidase in
Escherichia coli
Authors: Watanabe Hiroko , Watanabe Mamoru
Published: January 2020

Infection by ribonucleic acid (RNA) bacteriophage R23 inhibited the synthesis of β-galactosidase in
Escherichia coli.
The inhibition, although not complete, was apparent shortly after infection and was maximal after the first 20 min of infection. R23 diminished the β-galactosidase-synthesizing capacity when inducer was added after phage infection, but not when infection followed inducer removal. These findings suggested that the primary effect of R23 on enzyme-forming capacity was limitation of synthesis of enzyme-specific messenger RNA. Studies with ultraviolet irradiated phage and amber mutants of R23 indicated that the inhibitory process could be separated into two phases. Early inhibition did not require the expression of the viral genome, whereas late inhibition required the expression of the viral RNA synthetase cistron.