bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of In Vitro and Cell-Mediated Alteration of a Human Rhinovirus and Its Inhibition by Sodium Dodecyl Sulfate
Authors: Lonberg-Holm K. , Noble-Harvey J.
Published: January 2020

After human rhinovirus type 2 (HRV-2) attaches to HeLa cells, two types of subviral particles are formed which closely resemble particles produced in vitro by acid or heat. One type of particle contains RNA whereas the second sediments as an empty capsid and is RNA-deficient. Sodium dodecyl sulfate (SDS) at 10
−4
M inhibits the cell-mediated formation of these particles from HRV-2 virions and the ability of HRV-2 to form plaques, but it does not inhibit the formation of plaques by human rhinovirus 14 (HRV-14). SDS also stabilizes HRV-2 against inactivation by acid or heat to a much greater extent than it does HRV-14. In a similar manner, SDS protects against the acid inactivation of the subpopulation of HRV-2 natural top component particles which attach to virus-specific cellular receptors. This suggests that the loss of native properties of natural top component particles and of virion are related processes. The basis for this alteration and also its role in infection are discussed.
Defective Interfering Passages of Sindbis Virus: Chemical Composition, Biological Activity, and Mode of Interference
Authors: Weiss Barbara , Schlesinger Sondra
Published: January 2020

Defective interfering (DI) particles of Sindbis virus, appearing between the eighth and fourteenth passages, cosediment with and have the same buoyant density as standard virus. Virion RNA from such late passages is heterogeneous by polyacrylamide gel electrophoresis, whereas early passage RNA is homogeneous. No differences were found in the virion proteins from such passages. Cells co-infected with early and late passage virus synthesize as much intracellular viral-specific RNA and protein as is made after infection with early passage virus alone, although virus production is inhibited by 90% or more. Such cells synthesize two new intracellular species of RNA with molecular weights of 2.2 × 10
6
and 0.86 × 10
6
. Nucleocapsid assembly is blocked in these cells, and the amount of intracellular capsid protein made is reduced by 50%. The presence of a new intracellular protein in late passage infection was detected by polyacrylamide gel electrophoresis.
Properties of Nucleoprotein Complexes Containing Replicating Polyoma DNA
Authors: Goldstein David A. , Hall Mark R. , Meinke William
Published: January 2020

Short-lived nucleoprotein complexes (r-py complex) containing replicating polyoma DNA were isolated from infected cells after lysis with Triton X-100. The Triton lysing procedure of Green, Miller, and Hendler (1971) releases most complexes containing supercoiled viral DNA (py complex) from nuclei, but liberates only a portion of r-py complexes. r-py Complexes are associated more strongly with nuclear sites but can be extracted by prolonged incubation of nuclei in lysing solution. Complexes containing replicating polyoma DNA appear to be precursors to stable complexes containing supercoiled DNA. Sedimentation and buoyant density studies indicate that protein is bound to both r-py complexes and py complexes at a ratio of protein to DNA of about 1 to 2/1. Both types of complexes sediment as if the viral DNA is more compact than free DNA and both undergo major reversible configurational changes with increased salt concentration. Changes resulting from enzymatic and chemical treatment indicate that there may be two or more protein components in both r-py complex and py complex. One component is digested by Pronase and trypsin while another is resistant to the enzymes but released by deoxycholate. The abundance and similarity in chemical and physical properties of protein bound to all forms of polyoma DNA suggest that part of the protein molecules may serve in a structural capacity.
Nucleoprotein Complexes Containing Replicating Simian Virus 40 DNA: Comparison with Polyoma Nucleoprotein Complexes
Authors: Hall Mark R. , Meinke William , Goldstein David A.
Published: January 2020

Procedures for isolating nucleoprotein complexes containing replicating polyoma DNA from infected mouse cells were used to prepare short-lived nucleoprotein complexes (r-SV40 complexes) containing replicating simian virus 40 (SV40) DNA from infected monkey cells. Like the polyoma complexes, r-SV40 complexes were only partially released from nuclei by cell lysis but could be extracted from nuclei by prolonged treatment with solutions containing Triton X-100. r-SV40 complexes sedimented faster than complexes containing SV40 supercoiled DNA (SV40 complex) in sucrose gradients, and both types of SV40 nucleoprotein complexes sedimented ahead of polyoma complexes containing supercoiled polyoma DNA (py complex). The sedimentation rates of py complex and SV40 complex were 56 and 61
S
, respectively, based on the sedimentation rate of the mouse large ribosomal subunit as a marker. r-SV40 complexes sedimented as multiple peaks between 56 and 75
S.
Sedimentation and buoyant density measurements indicated that protein is bound to all forms of SV40 DNA at about the same ratio of protein to DNA (1-2/1) as was reported for polyoma nucleoproteins.
Factors Affecting Cell Fusion Induced by Sendai Virus
Authors: Wainberg M. A. , Howe C.
Published: January 2020

Cell fusion mediated by exogenous Sendai virus appears to occur in four temperature-dependent stages. The first two, which include viral adsorption, are pH dependent and can be inhibited by viral antibody. Viral envelope constituents remain detectable on the cell surface during the third stage and disappear only when cell-to-cell fusion supervenes. The relationship of these interactions to possible mechanisms of cell fusion are discussed.
Polyoma Pseudovirions II. Influence of Host Cell on Pseudovirus Production
Authors: Yelton David B. , Aposhian H. Vasken
Published: January 2020

The type of host cell influenced the relative amounts of pseudovirions and polyoma virions produced. The infection of primary mouse embryo cells resulted in the production of particles that were predominantly pseudovirions. Infection of baby mouse kidney or 3T3D cells yielded mainly infectious polyoma virus. The length of time that infection was allowed to continue also affected the amount of pseudovirions relative to polyoma virions. The longer the viral infection was allowed to proceed, the greater the quantity of pseudovirions produced. Pseudovirion production could be correlated with the fragmentation of host cell DNA to a size of approximately 3 × 10
6
daltons. The fragmentation of host cell DNA was much more extensive in primary mouse embryo cells than in the other cell types.
Physical and Chemical Properties of
Trichoplusia ni
Granulosis Virus Granulin
Authors: Summers Max D. , Egawa Kohji
Published: January 2020

The protein solubilized from the proteinic crystalline structure surrounding the granulosis virus of
Trichoplusia ni
by use of a carbonate buffer (pH 10.7) gives a major component, as analyzed by ultracentrifugation, with a molecular weight of 180,000. This protein has heterogeneous subunit structure as demonstrated by estimates of molecular weights by use of gel electrophoresis, amino-, and carboxy-terminal analyses, and peptide mapping of enzyme digests of the protein. The amino acid composition shows that the protein is acidic with a high percentage of amino acids with hydrophobic side groups. Optical rotatory dispersion studies reveal the presence of β-structure in the protein complex. The conversion of the β-structure to α-helix with sodium lauryl sulfate and to a random coil state with strong alkaline treatment are observed.
Replication of T4 DNA in
Escherichia coli
Treated with Toluene
Authors: Miller R. C. , Taylor D. M. , Mackay K. , Smith H. W.
Published: January 2020

Deoxyribonucleoside triphosphates are incorporated into T4 DNA in infected cells treated with toluene. Under the proper conditions the incorporation is controlled by the known T4 DNA polymerase and proceeds by a semiconservative mechanism. Both strands of the phage DNA are replicated into a high molecular weight progeny molecule. The replication system is accessible to extracellular pancreatic DNase added to the reaction mixture. At early times after infection a second replication system, not under control of the gene 43 polymerase, has been detected which synthesizes T4 DNA in toluenized cells.
Bacteriophage T4-Directed DNA Synthesis in Toluene-Treated Cells
Authors: Dicou Liana , Cozzarelli Nicholas R.
Published: January 2020

DNA synthesis has been studied in T4-infected
Escherichia coli
cells made permeable to nucleotides by treatment with toluene. The rate of incorporation of labeled deoxyribonucleoside triphosphates into DNA at various times after infection is proportional to the in vivo rate. This in vitro incorporation is dependent on all four deoxyribonucleoside triphosphates (5-hydroxymethyldeoxy-cytidine triphosphate can substitute for dCTP) and Mg
2+
. It is stimulated by rATP, partially inhibited by pancreatic DNase, and abolished by
N
-ethylmalei-mide and 1-β-
d
-arabinofuranosylcytosine triphosphate. T4 amber DO (DNA negative) and temperature-sensitive DO mutants under nonpermissive conditions of infection fail to induce DNA synthesis in vitro. The synthesizing activity is intracellular and the DNA product is exclusively T4 DNA. The in vitro synthesis proceeds in a discontinuous manner involving synthesis and subsequent joining of small DNA fragments (about 10
S
in alkaline sucrose gradients) into larger molecules predominantly one-half the length of mature T4 DNA. No restriction of C-containing or nonglucosylated HMC-containing T4 DNA product is observed in this system.
Proteins Specified by Herpes Simplex Virus XI. Identification and Relative Molar Rates of Synthesis of Structural and Nonstructural Herpes Virus Polypeptides in the Infected Cell
Authors: Honess Robert W. , Roizman Bernard
Published: January 2020

Analyses of polypeptides made in HEp-2 cells infected with herpes simplex virus type 1 by high-resolution polyacrylamide gel electrophoresis revealed the synthesis of at least 49 infected cell polypeptides (ICP) ranging in molecular weight from 15,000 to 280,000. Evidence for virus specificity based on increased rates of synthesis postinfection, immunological specificity, and viral control of mobility and rate of synthesis was available for 47 of the ICP. These 47 polypeptides can account for 75% of the virus genetic information assuming a DNA molecular weight of 10
8
and asymmetric transcription. On the basis of their mobility relative to virion proteins, the ICP were classified as structural (S, 23 polypeptides), nonstructural (NS, 16 polypeptides), and unassigned (U, 10 polypeptides). Analysis of the synthesis of the ICP revealed the following. (i) Rapid posttranslational cleavages of HSV proteins were not detected; in parallel experiments rapid posttranslational cleavages were readily demonstrated in poliovirus-infected cells and these were blocked by protease inhibitors. (ii) Slow posttranslational changes in the mobility of at least two polypeptides were observed. (iii) Analysis of the rates of synthesis of ICP examined at four intervals postinfection revealed regulation of the pattern and amount of ICP synthesized. ICP formed six classes (A to F) differing in their kinetics of synthesis. S and NS ICP were distributed nonrandomly among these classes. Thus, of the sum of S protein amino acid sequences apportioned among these kinetic classes, 47%, constituting class A and comprising “late” structural proteins, were characterized by progressively increasing rates of synthesis until at least 12 h postinfection; whereas “early” structural proteins constituting class C, amounting to 31% of the total amino acid sequences, were synthesized with initially increasing rates until 4 h postinfection and with declining rates thereafter. NS polypeptides and remaining S polypeptides were distributed among the other kinetic classes—B, D, E, and F. Control of protein abundance was evident in that the polypeptides were not made in equimolar amounts. However, S and NS polypeptides could not be differentiated on the basis of their molar rates of synthesis. The bulk of the detected polypeptides did not differ by more than eightfold in their molar rates of synthesis.
Effect of Dibutyryl Cyclic AMP on the Induction of Epstein-Barr Virus in Hybrid Cells
Authors: Zimmerman J. E. , Glaser R. , Rapp F.
Published: January 2020

Treatment of Epstein-Barr virus (EBV) negative somatic cell hybrids with 5′-iododeoxyuridine (IUdR) induced synthesis of EBV antigens and virus particles. When dibutyryl cAMP (Bt
2
-cAMP) was present in medium after exposure of cultures to IUdR, the incidence of cells synthesizing EBV early and virus capsid antigens was increased. The time necessary for appearance of EBV particles after induction by IUdR was significantly reduced in the presence of Bt
2
-cAMP. This enhancement was evident to a lesser degree with 3′:5′ cAMP than with Bt
2
-cAMP and did not occur with any other of the related compounds tested. The response observed was dose dependent. Untreated (no IUdR) EBV negative hybrid cells exposed to Bt
2
-cAMP also synthesized EBV antigens. The concentration of intracellular cAMP may act as one of the control mechanisms selecting for gene expression in this system.
Human Cytomegalovirus I. Purification and Characterization of Viral DNA
Authors: Huang Eng-Shang , Chen Sheng-Tu , Pagano Joseph S.
Published: January 2020

Two human strains (AD-169 and C87) and one simian strain (GR2757) of cytomegalovirus (CMV) have been purified from the extracellular fluids of virus-infected cultures by sedimentation through a sucrose gradient followed by brief centrifugation in a preformed gradient of CsCl. Enveloped virus particles were located in the density region, 1.219 g/cm
3
, and nucleocapsids at 1.263 g/cm
3
. Purified viral DNA, both human and simian, sedimented in the region of 55
S
in neutral sucrose gradients with herpes simplex type I DNA as a marker; the molecular weight of the CMV DNA was estimated as approximately 10
8
. The density of the viral DNA determined by analytical ultracentrifugation was 1.716 g/cm
3
for the human strains and 1.710 g/cm
3
for the simian strain. Tritiated viral complementary RNA synthesized in vitro with
Escherichia coli
transcriptase has been used for detection and localization of viral genome in membrane hybridization and in situ cytohybridization. Newly synthesized viral DNA appeared 24 h after infection and localized at two acrocentric areas; later the viral DNA distributed in a band resembling intranuclear inclusions 48 to 70 h after infection. Total DNA synthesis began to increase 24 h after infection and reached its peak at 70 h; RNA synthesis increased at 13 h, and reached its peak at 24 to 33 h. The viral DNA was also labeled with
3
H-TTP by repair-synthesis in vitro with Kornberg's enzyme in order to analyze the purity of the DNA and for detection of viral DNA by DNA-DNA reassociation kinetics.
Characterization of C-Type Particles Produced by a Tissue Culture-Adapted Murine Myeloma
Authors: Volkman Loy E. , Krueger R. G.
Published: January 2020

C-type particles produced by a tissue culture-adapted BALB/c myeloma were characterized. It was determined that although the particles were morphologically and antigenically similar to murine leukemia and sarcoma virus, the size of their RNA was different, they lacked RNA-dependent DNA polymerase, they were unstable in NET buffer, sucrose and citrate but were stable in glycerol and Earle balanced salt solution, and they behaved differently from oncornaviruses when treated with ether and detergent.
Induction of Hepatitis B Antibody in Experimental Animals by Immunization with A-2 Plaque Virus
Authors: Shaw E. D. , McKee A. P. , Rancourt M. , Hollenbeck L.
Published: January 2020

A sero-conversion for hepatitis B antibody has resulted from immunization of patas monkeys, guinea pigs, and rabbits with the A-2 plaque virus. This agent was isolated in tissue culture from patient sera that were positive for hepatitis B antigen. The immune response was assayed with techniques of direct and indirect counter-immunoelectrophoresis, and immune electron microscopy.
Herpesvirus Particles in Prostatic Carcinoma Cells
Authors: Centifanto Ysolina M. , Kaufman Herbert E. , Zam Z. Suzanne , Drylie David M. , Deardourff Stephen L.
Published: January 2020

Herpesvirus particles were found in cancer cells from a human prostate adenocarcinoma. These particles were identified as herpesvirus on the basis of specific immunofluorescence staining, morphology, and size.
Development of Coliphage N4: Ultrastructural Studies
Authors: Schito Gian Carlo
Published: January 2020

The basic properties of bacteriophage N4 development have been investigated in
Escherichia coli
Hfr 3300 under one-step growth and high cell density conditions. N4
r
+
-infected bacteria are lysis inhibited in mass culture, burst asynchronously starting 180 min postinfection, and release over 3,000 phage per cell. During lysis inhibition the bacteria continuously elongate, increase in girth, and undergo characteristic morphological changes represented by the appearance of dark spots located at the cell poles. In thin sections, during the late stages of replication and assembly, the phage particles are localized exclusively in restricted areas of the cytoplasm near the polar regions. Large paracrystalline arrays of virions are found in over 7% of the cells before lysis. The most common mechanism of lysis consists in the formation of bulges located at random in the cell circumference; these burst and, without extensive disruption of the cell wall, the phage progeny escapes into the medium.
Isolation and Characterization of a Generalized Transducing Bacteriophage for
Acinetobacter
Authors: Herman Norma J. , Juni Elliot
Published: January 2020

A series of bacteriophages which grow in various strains of
Acinetobacter
have been isolated. One of these, phage P78, which forms turbid plaques on
Acinetobacter
strain 78 is specific for this particular host and fails to attack 389 other independently isolated strains of
Acinetobacter
. Phage P78 appears to be a temperate phage which lysogenizes its host. Various agents such as
N
-methyl-
N
′-nitro-
N
-nitrosoguanidine, diethyl sulfate, mitomycin C, and ultraviolet light are effective inducers of the lysogen. Phage lysates of wild-type cells are capable of transducing auxotrophs of strain 78 to prototrophy at frequencies ranging from 0.3 × 10
−7
to 34 × 10
−7
per plaque-forming unit adsorbed. To date, no linkage has been detected between any of the markers studied in two-factor crosses. Donor phage grown in one particular mutant, strain 78 (
arg-1
), has been shown to give rise to significantly higher transduction frequencies than when phage is grown on wild-type or other auxotrophic strains. Phage P78 is rapidly adsorbed to its bacterial host and has a latent period of 25 min, and infection results in a burst size of approximately 50. Some of the physical properties of phage P78 and its DNA are described.
Translation of Vesicular Stomatitis Messenger RNA by Extracts from Mammalian and Plant Cells
Authors: Morrison Trudy , Stampfer Martha , Baltimore David , Lodish Harvey F.
Published: January 2020

RNA was isolated from polyribosomes of vesicular stomatitis virus (VSV)-infected cells and tested for its ability to direct protein synthesis in extracts of animal and plant cells. In cell-free, non-preincubated extracts of rabbit reticulocytes, the 28
S
VSV RNA stimulated synthesis of a protein the size of the vesicular stomatitis virus L protein whereas the 13 to 15
S
RNA directed synthesis of the VSV M, N, NS, and possibly G proteins. In wheat germ extracts, 13 to 15
S
RNA also directed synthesis of the N, NS, M, and possibly G proteins. Analysis of extracts labeled with formyl [
35
S]methionine showed that the 28
S
RNA directed the initiation of synthesis of one protein, whereas the 13 to 15
S
RNA directed initiation of at least four proteins. It is concluded that the 28
S
RNA encodes only the L protein, whereas the 13 to 15
S
RNA is a mixture of species, presumably monocistronic, which code for the four other known vesicular stomatitis virus proteins.
Control of Simian Virus 40 Gene Expression in Adenovirus-Simian Virus 40 Hybrid Viruses Synthesis of Hybrid Adenovirus 2-Simian Virus 40 RNA Molecules in Cells Infected with a Nondefective Adenovirus 2-Simian Virus 40 Hybrid Virus
Authors: Oxman Michael N. , Levin Myron J. , Lewis Andrew M.
Published: January 2020

The effect of interferon on simian virus 40 (SV40) and adenovirus 2 (Ad2) T antigen synthesis has been examined in cells infected with SV40, with Ad2, and with a nondefective Ad2-SV40 hybrid virus, Ad2
+
ND
4
. The induction of SV40 T antigen by SV40 was highly sensitive to interferon, whereas the induction of Ad2 T-antigen by Ad2 was resistant. This difference in interferon sensitivity was also noted in cells simultaneously infected with both viruses. However, the induction of SV40 T antigen by Ad2
+
ND
4
, which contains covalently linked SV40 and Ad2 DNAs, was as resistant to interferon as the induction of Ad2 T antigen. This change in the interferon sensitivity of SV40 T antigen synthesis suggests that the expression of at least this portion of the SV40 genetic information in Ad2
+
ND
4
is under Ad2 genetic control. When RNA extracted from Ad2
+
ND
4
-infected cells was examined by means of sequential hybridization with Ad2 DNA, elution, and rehybridization with SV40 DNA, 27% of the SV40-specific RNA was found to be linked to Ad2 RNA. No such linkage was detected in control mixtures of Ad2 and SV40 RNAs. The presence of Ad2 and SV40 nucleotide sequences in the same RNA molecule implies that, in Ad2
+
ND
4
infection, transcription is initiated in the DNA of one virus (Ad2 or SV40) and continues without interruption across the point of junction into the DNA of the other virus. Furthermore, the interferon resistance of Ad2
+
ND
4
-induced SV40 T antigen synthesis suggests that transcription of the genetic information for SV40 T antigen is initiated in a region of Ad2 DNA.
Relationship of mRNA from Productively Infected Cells to the Complementary Strands of Adenovirus Type 2 DNA
Authors: Tibbetts Clark , Pettersson Ulf , Johansson Katarina , Philpson Lennart
Published: January 2020

The complementary strands of adenovirus type 2 (Ad2) DNA were separated by buoyant density gradient centrifugation with poly (U, G). The complementary strand DNA was shown to remain intact through the course of strand separation. The l-strand of Ad2 DNA, appearing in the less dense complex with poly (U, G) in neutral CsCl density gradients, was shown to have a buoyant density in alkaline (pH 12.5) CsCl density gradients which is 2 to 3 mg per ml greater than that of its complement (h-strand). Renaturation of purified complementary strand DNA was observed only in mixtures of h- and l-strand DNA, and then with the second-order reaction rate expected for Ad2 DNA. Hybridization of the complementary strands of Ad2 DNA with cytoplasmic mRNA isolated from infected HeLa cells was performed in liquid phase and analyzed by hydroxylapatite chromatography. Before viral DNA synthesis (6 h after infection), 13 to 18% of the h-strand and 30 to 35% of the l-strand were represented in viral mRNA. Late (18 h) after infection the mRNA represented 20 to 25% and 63 to 68% of the h- and l-strands, respectively. Most, if not all sequences present in viral mRNA before viral DNA synthesis were also present in the cytoplasm late in infection.
Phosphorylation of Vesicular Stomatitis Virus In Vivo and In Vitro
Authors: Moyer Sue A. , Summers Donald F.
Published: January 2020

The structural protein, NS, of purified vesicular stomatitis virus (VSV) is a phosphoprotein. In infected cells phosphorylated NS is found both free in the cytoplasm and as part of the viral ribonucleoprotein (RNP) complex containing both the 42
S
RNA and the structural proteins L, N, and NS, indicating that phosphorylation occurs as an early event in viral maturation. VSV contains an endogenous protein kinase activity, probably of host region, which catalyzes the in vitro phosphorylation of the viral proteins NS, M, and L, but not of N or G. The phosphorylated sites on NS appear to be different in the in vivo and in vitro reactions, and are differentially sensitive to alkaline phosphatase. After removal of the membrane components of purified VSV with a dextran-polyethylene glycol two-phase separation, the kinase activity remains tightly associated with the viral RNP. However, viral RNP isolated from infected cells shows only a small amount of kinase activity. The protein kinase enzyme appears to be a cellular contaminant of purified VSV because an activity from the uninfected cell extract can phosphorylate in vitro the dissociated viral proteins NS and M. The virion-associated activity may be derived either from the cytoplasm or the plasma membrane of the host cell since both of these cellular components contain protein kinase activity similar to that found in purified VSV.
Proteins Specified by Sindbis Virus in HeLa Cells
Authors: Snyder H. W. , Sreevalsan T.
Published: January 2020

HeLa cells infected with Sindbis virus were found to contain five species of nonvirion proteins besides the structural proteins of the virus. Some of the nonvirion proteins were found to serve as precursors to the viral structural proteins in a pulse-chase experiment.
Unfolding of the Host Genome After Infection of
Escherichia coli
with Bacteriophage T4
Authors: Tutas Daniel J. , Wehner Jeanne M. , Koerner James F.
Published: January 2020

The folded genome of
Escherichia coli
is converted to a slower-sedimenting form within 5 min after infection with bacteriophage T4 or T4
nd
28(
den
A)-
am
N82(44). Chloramphenicol sensitivity and response to UV-irradiation of the phage suggest participation of viral-induced functions.
Polymerase Activity of Pichinde Virus
Authors: Carter Michael F. , Biswal Nilambar , Rawls William E.
Published: January 2020

Pichinde virus, a member of the arenavirus group, was examined for polymerase activity. Purified virus was found to contain RNA-dependent RNA polymerase but not RNA-dependent DNA polymerase activity. Since RNase but neither DNase nor actinomycin D inhibited the endogenous polymerase reaction, RNA of the virus appeared to be used as the template. The divalent cations Mg
2+
and Mn
2+
were required for optimal reactivity. The RNA product was partially resistant to RNase and the resistant portion had a sedimentation coefficient of 22 to 26
S
in sucrose gradients.
Preparation of Plasmid λdv from Bacteriophage λ: Role of Promoter-Operator in the Plasmid Replicon
Authors: Matsubara Kenichi
Published: January 2020

A technique has been described for selection of bacteria carrying plasmid λdv. With this technique, the effects of mutations in the promoter-operators were compared on the production and perpetuation of the plasmid. It was found that “left” promoter-operator that controls leftward gene expressions can be deleted from the plasmid genome. Some mutations of “right” promoter-operator (pRoR) that controls expression of genes
tof, O
, and
P
affect the stability of the plasmid. However, the plasmid genome accomodates a variety of pRoR mutations within a reasonable but different degree of constitutivity. Some new promoter mutations that allow bypass of the pRoR cannot be carried in the plasmid genome. From these findings it was proposed that the plasmid replicon has one indispensable promoter-operator that controls expression of all the genes related to its own replication, although a variety of constitutive mutations can be accommodated in the pRorR.
Bacteriophage T4-Mediated Release of Envelope Components from
Escherichia coli
Authors: Loeb Marilyn R.
Published: January 2020

When
Escherichia coli
B, labeled by prior growth in
14
C-glucose, are infected with T4 phage there is a rapid release of
14
C-nondialyzable material into the medium. About half of this material is derived from the cell envelope as evidenced by its content of phospholipid and lipopolysaccharide and its buoyant density upon isopycnic ultracentrifugation of 1.19 g/cm
3
. It is similar in its gross chemical and physical properties to envelope material released at a lower rate from growing uninfected cells or from cells whose protein synthesis is inhibited by chloramphenicol (22). The rate of release of this envelope material at a multiplicity of infection (MOI) of 10 is greatest in the first minute after infection, and release is completed by 4 min. The rate of its release, as a function of MOI at 2 min after infection, is greatest at low MOI (e.g., MOI 2 and 4); in addition, the release does not continue above MOI 30. The main conclusion derived from the data is that phage, as part of the process of adsorption and injection of DNA, cause an increased release of envelope substance from the cells. With the assumption that all of the envelope material released is derived from the outer envelope, it is estimated that uninfected cells release 20 to 30% of their outer envelope per hour, whereas infected cells release 30% in 2 min at MOI 30. Further, because release does not continue at high MOI, this phenomenon is not considered to be a direct cause of lysis from without. Data are also presented on the amounts of other non-dialyzable
14
C-components released and on the differences in the kinetics of release from chloramphenicol-treated cells compared to phage-infected cells. To avoid the possibility that the release is due to phage lysozyme which is an adventitious “contaminant” of wild-type phage, a phage mutant (T4BeG59s) devoid of this enzyme was used in these experiments.
Antigenic Phenotypes and Complementation Groups of Temperature-Sensitive Mutants of Simian Virus 40
Authors: Robb James A. , Tegtmeyer Peter , Ishikawa Akira , Ozer Harvey L.
Published: January 2020

The antigenic phenotypes of several temperature-sensitive mutants of simian virus 40 were determined by an immunofluorescence microtechnique that allowed a very high degree of internal control for the conditions of virus infection and antigenic staining. The tumor (T), U, capsid protein (C), and virion (V) antigens were investigated. Productive infection in monkey cells and abortive infection in mouse cells were simultaneously monitored for antigen production at both permissive and restrictive temperatures. Complementation analyses of the mutants demonstrated two complementing groups (A and B) and one noncomplementing group (
*
). One of the complementing groups could be subdivided into two subgroups having very different antigenic phenotypes. The following phenotypes were observed at the restrictive temperature in monkey cells. (i) The noncomplementing group produced none of the antigens. (ii) Group A induced T antigen in moderately but consistently reduced numbers of cells. Other antigens were markedly reduced or absent. (iii) Some of the group B mutants produced T antigen but little or no U and V antigens. The C antigen appeared in the nucleolus and cytoplasm of this subgroup. (iv) In the other group B mutants, antigen synthesis was not altered. Similar phenotypes were observed in mouse cells, except that U, C, and V antigens could not be detected during either the mutant or wild-type virus infections at any temperature.
Studies of Nondefective Adenovirus 2-Simian Virus 40 Hybrid Viruses IX. Template Topography in the Early Region of Simian Virus 40
Authors: Patch Cephas T. , Lewis Andrew M. , Levine Arthur S.
Published: January 2020

The DNAs of the five nondefective adenovirus 2 (Ad2)-simian virus 40 (SV40) hybrid viruses contain overlapping segments of the early region of wild-type SV40 DNA. The complementary DNA strands of these five viruses have been separated with synthetic polyribonucleotides in isopycnic cesium chloride gradients. The relative amounts of early and late SV40 template in the DNA of each virus were determined by RNA-DNA hybridization with late lytic SV40 RNA, which contains sequences complementary to both templates. From the distribution of early and late templates in the five overlapping SV40 segments, we conclude that either the entire early region of SV40 is symmetrically transcribed in vivo, or, more probably, that the early SV40 templates are not contiguous.
Characterization of an Endogenous RNA-Dependent DNA Polymerase Associated with Murine Intracisternal A Particles
Authors: Yang Stringner Sue , Wivel Nelson A.
Published: January 2020

An RNA-dependent DNA polymerase associated with intracisternal A particles has been characterized. The enzyme required Mg
2+
or Mn
2+
, dithiothreitol and the presence of all four deoxyribonucleoside triphosphates for the expression of maximal activity. Sensitivity of the endogenous RNA-dependent DNA polymerase activity to a low concentration of pancreatic ribonuclease in the presence of a high concentration of NaCl suggested that the enzyme might be utilizing the A particle endogenous RNA as template. Evidence in support of this was provided by analyses of early and late DNA products of the endogenous reaction by Cs
2
SO
4
isopycnic gradient centrifugation and hybridization of purified 60 to 70
S
and 35
S
RNAs of A particles with the purified DNA product.
Selective Inhibition of Newcastle Disease Virus-Induced Glycoprotein Synthesis by
d
-Glucosamine Hydrochloride
Authors: Samson A. C. R. , Fox C. Fred
Published: January 2020

d
-Glucosamine selectively affected the synthesis of virus-induced glycoproteins in Newcastle disease virus-infected chick fibroblasts, but had no effect upon post-translational cleavage of the glycoprotein precursor for one of the two major glycoproteins of the mature virion. In response to glucosamine, at least one of the two virus-induced glycoproteins is formed in reduced quantity and the second is either not formed or has an electrophoretic mobility identical to that of another virus-induced protein.
Protein Synthesis in Newcastle Disease Virus-Infected Chicken Embryo Cells
Authors: Hightower Lawrence E. , Bratt Michael A.
Published: January 2020

A double-isotopic label difference analysis of polyacrylamide gels has been used to distinguish between cellular and viral protein accumulation in infected cells and to quantify the kinetics of accumulation of viral polypeptides. This technique, coupled with the determination of total radioactive amino acid incorporation in infected cultures, has revealed the following kinetic patterns. Viral polypeptides are first detected in infected cultures 2.0 to 2.5 h postinfection. The rate of accumulation of radioactive amino acids in viral polypeptides increases to a maximum (30 to 35% of the rate of accumulation in uninfected control cultures), whereas the rate of accumulation of radioactive amino acids in host-cell protein decreases to a minimum (20% of the rate of accumulation in uninfected control cultures) by 5 to 6 h postinfection. All of the viral polypeptides detected late in infection are also present at the earlier times, and the major virion structural polypeptides are present in approximately the same (N/G-2, 53K) or slightly increasing (L, G-1, M) relative amounts. One peak area containing a nonstructural glycopeptide with an apparent molecular weight of 66,000 shows significant alterations in rates of accumulation during infection. Inhibition in the rate of radioactive amino acid incorporation into both trichloroacetic acid-soluble and acid-precipitable material during infection has been demonstrated. However, these two inhibition phenomena can be uncoupled temporally by incubating infected cultures at 36 C instead of the usual 40 C, suggesting that they may not be directly related.
Effect of
d
-Penicillamine on Poliovirus Replication In HeLa Cells
Authors: Merryman Parvin , Jaffe Israeli A. , Ehrenfeld Ellie
Published: January 2020

A series of mercaptan compounds were studied with respect to their ability to inhibit the growth of poliovirus in cultured cells. Of the compounds tested only
d
-penicillamine possessed antiviral activity. There was no direct effect on the virus itself, nor were the processes of adsorption, penetration and uncoating, or virus-induced “shut-off” of host cell protein synthesis inhibited. At concentrations where there was no effect on host cell RNA or protein synthesis,
d
-penicillamine caused a marked inhibition of virus-specific RNA and protein synthesis. Although much reduced, the relative concentrations of single-stranded and double-stranded viral RNA synthesized in the presence of
d
-penicillamine was unchanged. Similarly, all apparent precursor and cleavage product proteins could be synthesized in the presence of the drug. The inhibitory effect was reversible, after a lag of 1.5 to 2 h after removal of the drug, and normal yields of virus could be obtained. The structural and functional properties of
d
-penicillamine are discussed in relation to requirements for anti-polioviral activity.
Comparison of Two Human Papovaviruses with Simian Virus 40 by Structural Protein and Antigenic Analysis
Authors: Mullarkey Michael F. , Hruska Jerome F. , Takemoto Kenneth K.
Published: January 2020

The proteins of simian virus 40 (SV40) and two human papovaviruses, the hemagglutinating BK virus and the non-hemagglutinating DAR virus, were analyzed and compared by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The virions of SV40 and DAR contain seven proteins. By molecular weight analysis the constituent proteins of SV40 and DAR are identical. Approximately 84% of the viral protein has a molceular weight of 45,000. The major protein of BK virus is 3,000 to 5,000 daltons lighter than the major proteins of SV40 and DAR viruses. The five most rapidly migrating proteins of BK virus are indistinguishable by molecular weight analysis from the corresponding proteins of SV40 and DAR viruses. Radial immunodiffusion and immunoelectrophoresis of whole virus gave lines of identity between SV40 and DAR when reacted with SV40 antibody. SV40 antiserum tested against BK virus and BK antiserum tested against SV40 virus showed no reactivity by complement fixation, immunodiffusion, or immunoelectrophoresis.
Interaction of Mycoplasma with Viruses I. Primary Adsorption of Virus Is Ionic in Mechanism
Authors: Fraser Dean , Fleischmann Christina
Published: January 2020

We have studied the adsorption of the Gourlay
Acholeplasma
virus MVL-1 to the host cell
Acholeplasma laidlawii
JA-1. Successful adsorption depends primarily on some unknown action of the serum factor in the medium, but evaluation of various physical parameters indicates clearly that given this factor the kinetics is pseudo first order (K = 3 × 10
−9
cm
3
/min) and the mechanism ionic. Chiefly important are the ionic strength of the cation and pH (optimal Na
+
= 0.08 M, pH = 6). The system seems indifferent to whether the cation is Na, K, NH
4
, Ca, or Mg. There is little effect of temperature over the range 0 to 42 C. The diffusion constant of the virus, calculated from its geometry or its maximum adsorption rate, is consistent with its reported size and shape.
Hamster Leukemia Virus: Lack of Endogenous DNA Synthesis and Unique Structure of Its DNA Polymerase
Authors: Verma Inder M. , Meuth Nora L. , Fan Hung , Baltimore David
Published: January 2020

Infectious hamster leukemia virus (HaLV) contains a DNA polymerase different from those of murine and avian viruses. No endogenous reaction directed by the 60 to 70
S
RNA of HaLV could be demonstrated in detergenttreated HaLV virions, nor could the purified DNA polymerase copy added viral RNA. The virion RNA could, however, act as template for added avian myeloblastosis virus DNA polymerase and the HaLV DNA polymerase could efficiently utilize homopolymers as templates. The HaLV enzyme was like other reverse transcriptases in that certain ribohomopolymers were much better templates than the homologous deoxyribohomopolymers. No ribonuclease H activity could be shown in the HaLV enzyme, but neither could activity be found in the murine leukemia virus DNA polymerase. The hamster enzyme was unique in that poly(A) ·oligo(dT) was a poor template, and globin mRNA primed with oligo(dT) was totally inactive as a template. Its uniqueness was also indicated by its subunit composition; electrophoresis of the HaLV DNA polymerase in sodium dodecyl sulfate-containing polyacrylamide gels revealed equimolar amounts of two polypeptides of molecular weight 68,000 and 53,000. The sedimentation rate of the enzyme in glycerol gradients was consistent with a structure containing one each of the two polypeptides. The enzyme thus appears to be structurally distinct from other known virion DNA polymerases. Its inability to carry out an endogenous reaction in vitro might result from an inability to utilize certain primers.
Evidence for Heterogeneity in Populations of T5 Bacteriophage
Authors: Labedan B. , Legault-Demare J.
Published: January 2020

Each T5 stock contains a population of particular phages that, just after adsorption onto the host bacteria. release their entire chromosome outside the bacterial membrane in a place where it is sensitive to bacterial enzymes. This release takes place before the sensitization step to deprivation of calcium and before the transfer of the first-step DNA fragment. Secondarily, this released DNA is degraded by bacterial enzymes, mainly by the endonuclease I; the products of degradation are spontaneously released in the surrounding medium. Thus, in each T5 phage stock it seems that there is a minor population that is deficient for the mechanism of controlled DNA injection into the bacteria.
Host DNA Synthesis-Suppressing Factor in Culture Fluid of Tissue Cultures Infected with Measles Virus
Authors: Minagawa Tomonori , Nakaya Chikako , Iida Hiroo
Published: January 2020

Host DNA synthesis is suppressed by the culture fluid of cell cultures infected with measles virus. This activity in the culture fluid is initiated somewhat later than the growth of infectious virus. Ninety percent of host DNA synthesis in HeLa cells is inhibited by culture fluid of 3-day-old cell cultures of Vero or HeLa cells infected with measles virus. This suppressing activity is not a property of the virion, but is due to nonvirion-associated component which shows none of the activities of measles virus such as hemagglutination, hemolysis, or cell fusion nor does it have the antigenicity of measles virus as tested by complement-fixation or hemagglutination-inhibiting antibody blocking tests. Neutralization of the activity of this component is not attained with the pooled sera of convalescent measles patients. This component has molecular weights of about 45,000, 20,000, and 3,000 and appears to be a heat-stable protein. The production of host DNA suppressing factor (DSF) is blocked by cycloheximide. Neither UV-inactivated nor antiserum-neutralized measles virus produce DSF. Furthermore, such activity of nonvirion-associated component is not detected in the culture fluid of cultures infected with other RNA viruses such as poliovirus, vesicular stomatitis virus, or Sindbis virus.
DNA Polymerase in the Core of the Human Hepatitis B Virus Candidate
Authors: Robinson William S. , Greenman Richard L.
Published: January 2020

Experiments were done to show that the human hepatitis B antigen (HBAg)-associated DNA polymerase is a component of Dane particles and their antigenically distinct cores prepared by Nonidet P-40 detergent treatment of Dane particles. Before detergent treatment, the DNA polymerase was precipitated by serum containing anti-HB surface antigen (anti-HB
s
) but not with serum containing anti-HB core antigen (anti-HB
c
). After detergent treatment, the enzyme was precipitated by anti-HB
c
- and not by anti-HB
s
-containing serum. Highly purified 16- to 25-nm HBAg particles blocked only the precipitation of DNA polymerase in untreated HBAg preparations. The 110
S
structure with which the DNA reaction product remains associated in Nonidet P-40-treated preparations was identified as Dane particle core by immunoprecipitation with serum containing anti-HB
c
. The DNA polymerase and the radioactive DNA reaction product were used as markers for core in immunoprecipitation tests for anticore. In such assays, 8 of 11 human sera with anti-HB
s
activity and all of 10 sera from chronic HBAg carriers were found to contain anti-HB
c
activity.
Origin of Reovirus Oligo(A)
Authors: Carter C. , Stoltzfus C. M. , Banerjee A. K. , Shatkin A. J.
Published: January 2020

Reovirus contains about 1,200 molecules per virion of oligo(A) of chain length 10 to 15 nucleotides in addition to the 10 double-stranded genome segments. Virions purified from infected BHK, HeLa, or L cells had similar amounts of oligo(A) of the same composition, indicating that it is a virus-specific product. Although conversion of virions to cores by chymotryptic digestion resulted in an almost complete loss of oligo(A) and a marked decrease in infectivity, the infectivity could be partially restored by adsorbing cores to cells in the presence of Kaopectate. Core-infected cells yielded virions that contained a normal complement of oligo(A). The results indicate that oligo(A) is not essential for infectivity or required as a primer/template for its own synthesis.
Structural Aberrations in T-Even Bacteriophage V. Effects of Canavanine on the Maturation and Utilization of Specific Gene Products
Authors: Bolin Rex W. , Cummings Donald J.
Published: January 2020

Previous results have shown that when a T-even bacteriophage-infected cell was exposed to
l
-canavanine followed by an exposure to
l
-arginine, a monster phage particle, termed a lollipop, was formed.
l
-Canavanine was necessary for the induction event but
l
-arginine was required for the maturation of the particle. We now describe the effects of canavanine on the maturation of certain T4 proteins and their role in the induction of lollipops. The cleavage reactions of the head proteins P22, P23, P24, and IPIII are prevented by
l
-canavanine as shown by the accumulation of the precursor proteins and the failure of the cleaved products to appear.
l
-Canavanine also prevents the appearance of P12 (tailplate protein) and P20 (head protein) indicating that these proteins may undergo a proteolytic cleavage during normal assembly. The formation of P10 (tailplate protein) and P18 (tail sheath protein) is also affected by
l
-canavanine. The data suggest that P23 in conjunction with P20 plays a major role in the determination of the length of the phage head.
Deficiency of 60 to 70
S
RNA in Murine Leukemia Virus Particles Assembled in Cells Treated with Actinomycin D
Authors: Levin Judith G. , Grimley Philip M. , Ramseur Janet M. , Berezesky Irene K.
Published: January 2020

Production of particles with the ultrastructural appearance of C-type virions persisted for at least 6 h in actinomycin D-treated cells infected with murine leukemia virus. This phenomenon occurred despite severe inhibition of viral RNA synthesis. Virus particles present in a 6-h harvest sedimented in sucrose gradients with the buoyant density characteristic of RNA tumor viruses (1.16 g/cm
3
) and exhibited high levels of reverse transcriptase activity in response to the exogenous template polyriboadenylic acid·oligo deoxythymidylic acid in the range of untreated controls. However, RNase-sensitive endogenous activity was only ⅕ the level found in controls. This observation correlated with a marked reduction in infectivity. Kinetic studies on the appearance of labeled RNA in banded virions revealed that within the first hour after addition of actinomycin D, particles contained 60 to 70
S
RNA and two low-molecular-weight RNA species corresponding to 8 and 4
S
RNA. After approximately 1 h of incubation with actinomycin D, 60 to 70
S
RNA could not be detected and 4
S
RNA was the predominant species. These findings suggest that murine leukemia virus particles assembled in the presence of actinomycin D are deficient in 60 to 70
S
viral RNA.