bluuebunny/crossref_metadata_2025 huggingface dataset:
Structure of Isometric Viruses Containing Nonidentical Polypeptide Chains
Authors: Dunker A. Keith
Published: January 2020

The theory of Caspar and Klug (1962) for the structure of isometric viruses has been generalized to the case in which the identical repeating unit is composed of
n
nonidentical polypeptide chains. This modified theory accounts for the structure of picornaviruses, the lambda phage head, cowpea mosaic virus, and φX174, while at the same time conserving the principle of having identical subunits in identical environments. Furthermore, the modified theory suggests amending the triangulation number to
T
[
n
] for capsids with
n
nonidentical polypeptide chains as the repeating unit.
Temperature-Sensitive Mutants of Murine Leukemia Virus IV. Further Physiological Characterization and Evidence for Genetic Recombination
Authors: Stephenson John R. , Tronick Steven R. , Aaronson Stuart A.
Published: January 2020

Several temperature-sensitive mutants of the Rauscher strain of murine leukemia virus representing three distinct physiological groups have been further characterized. Genetic recombination between different pairs of these mutants has been demonstrated. Several representative genetic recombinants were isolated and shown to replicate equally well at the permissive (31 C) and nonpermissive (38 C) temperatures and to have serological characteristics of the wild-type parental virus. Alternative models for the mechanisms involved in recombination between type C RNA viruses are discussed.
Structure of Infectious Bursal Disease Virus
Authors: Hirai K. , Shimakura S.
Published: January 2020

Infectious bursal disease virus of chickens was purified, and its structure was examined by the negative-staining technique in the electron microscope. The buoyant density of infectious bursal disease virus in CsCl was found to be 1.34 g/cm
3
. The morphological details suggest that the capsid of the virion consists of a single layer of 32 capsomeres arranged in 5:3:2 symmetry. The virion measured about 55 nm in diameter and had no envelope.
Inhibition of Glycosylation of the Influenza Virus Hemagglutinin
Authors: Schwarz Ralph T. , Klenk Hans-Dieter
Published: January 2020

d
-Glucosamine and 2-deoxy-
d
-glucose interfere with the biosynthesis of the hemagglutinin glycoproteins. With increasing inhibitor concentrations a progressive decrease in size of the precursor HA and the cleavage products, HA
1
and HA
2
can be observed. The shift in molecular weight is paralleled by a decrease of the carbohydrate content. This was shown by labeling studies with radioactive sugars which revealed that the inhibitors block the incorporation into glycoproteins, whereas they have no or only slight effects on the uptake and activation of sugars. Under conditions of maximal inhibition, the hemagglutinin proteins lack all or most of their carbohydrates. These findings indicate that the inhibitory effect of
d
-glucosamine and 2-deoxy-
d
-glucose is due to an impairment of glycosylation. When glycosylation is inhibited, the precursor polypeptide is synthesized at normal rates. Its cleavage products, however, are very heterogeneous. This suggests that carbohydrate protects the hemagglutinin from proteolytic degradation.
Infectious Rous Sarcoma Virus and Reticuloendotheliosis Virus DNAs
Authors: Cooper Geoffrey M. , Temin Howard M.
Published: January 2020

An efficient and quantitative assay for infectious Rous sarcoma virus and reticuloendotheliosis virus DNAs is described. The specific infectivities of viral DNA corresponded to one infectious unit per 10
5
to 10
6
viral DNA molecules. Infection with viral DNA followed one-hit kinetics. The minimal size of infectious Rous sarcoma virus DNA was approximately 6 million daltons, whereas the minimal size of infectious reticuloendotheliosis virus DNA was larger, 10 to 20 million daltons.
Expression of the Viral Thymidine Kinase Gene in Herpes Simplex Virus-Transformed L Cells
Authors: Lin Shie-Sheng , Munyon William
Published: January 2020

In these studies, the expression of thymidine kinase (TK) in normal and herpes simplex virus (HSV)-transformed L cells has been compared. In asynchronously dividing cultures of L cells, the TK activity rose and declined rapidly and coordinately with DNA synthesis. When net cell increase stopped, TK activity was at a minimum. In contrast, TK activity of HSV-transformed cells remained at a minimum during rapid DNA synthesis and gradually increased as the rate of DNA synthesis decreased. When net cell increase stopped, TK activity was at a maximum. In synchronous cultures of L cells, TK activity rose and fell coordinately with the rate of DNA synthesis. In synchronous cultures of HSV-transformed cells, no increase in TK activity was observed during the period of rapid DNA synthesis, i.e., the S phase. These findings indicated that the viral TK gene in HSV-transformed cells was not placed under the control of the cellular mechanisms which normally modulate the host cell TK gene. Lytic infection of HSV-transformed cells with a TK
−
mutant of HSV-1 induced a four-to fivefold increase in viral TK. The TK of HSV-1 was induced in the HSV-1-transformed cells and HSV-2 in the HSV-2-transformed cells by this TK
−
mutant. The same infection of normal L cells decreased the cellular TK activity by 80%. This stimulation, rather than inhibition, suggest that the viral gene in HSV-transformed cells retain some of its original viral characteristics.
Effects of Actinomycin D on the Cytopathology Induced by Poliovirus in HEp-2 Cells
Authors: Guskey Louis E. , Wolff David A.
Published: January 2020

One possible mechanism of virus-induced cell damage is that the redistributed (released) lysosomal enzymes produce the cytopathic effect during cytolytic types of infections such as poliovirus in HEp-2 cells. To determine if the lysosomal enzyme redistribution and cell damage are host-cell directed, we studied sensitivity of these events to the action of actinomycin D. By the use of actinomycin D at concentrations producing the least toxicity but maximal effectiveness in shuting down cell RNA synthesis, it was shown that the cytopathic effect and enzyme redistribution were not inhibited and, therefore, not directly controlled and induced by the cell genome in response to the virus infection. Evaluation of cytopathic effect by a phase contrast microscopy method detected changes earlier than the erythrocin B uptake method.
Complementation by Restricted Phage T1
Authors: Christensen J. R.
Published: January 2020

The ability of restricted phage T1
hr
to complement stocks of T1
am
mutants carrying the P1 modification has been tested in mixed infection of
Escherichia coli
B(P1). Of the 18 genes tested, 15 could be complemented to give successful infection of approximately 10 to 25% of the cells, and 2 other genes consistently gave at least 5% complementation. The progeny phage produced in these infections was predominantly of the
hr
+
am
genotype. A mutant in gene 12 could be complemented very poorly, if at all. With one double mutant stock, the complementation obtained was nearly as good as the more poorly complemented of the two corresponding single mutants.
Interactions Between the Vegetative States of Phages λ and T1
Authors: Geiman Joyce M. , Christensen J. R. , Drexler Henry
Published: January 2020

Bacteria containing phage lambda in the vegetative state were produced either by induction of λ lysogens or by infection of sensitive cells with λ. These cells were superinfected with T1, and assayed for the production of λ, T1, or both. Although most of the cells produced only λ or T1, approximately 10% of the infectious centers were dual yielders. Examination of the progeny phage produced by the population of mixedly-infected cells showed that there was little, if any, phenotypic mixing, as determined by adsorption phenotype. T1
am
mutants in a variety of T1 genes were tested for their ability to exclude λ, but none were defective in this ability. One gene of T1, gene 4, can be complemented by λ.
Role of Genetic Recombination in DNA Replication of Bacteriophage Lambda I. Genetic Characterization of the Delta Gene
Authors: Barta K. , Tavernier P. , Zissler J.
Published: January 2020

We describe the isolation and genetic characterization of point mutations in gene delta, including a temperature-sensitive mutation (
del
206
). Genetic methods enable the extraction of a delta mutation from the triple mutant (
del,red,gam
) and the construction of new genotypes, including
del,red
and
del,gam
double mutants. Tests of plating efficiency indicate gene delta is essential for normal phase growth on the
polA
host. The possible association of delta in a system involving alpha, beta, and gamma is considered.
Extent of Double Strandedness in Avian Myeloblastosis Virus RNA
Authors: Cavalieri Liebe F.
Published: January 2020

The extent of double strandedness of avian myeloblastosis virus 70
S
RNA has been determined from fluorescence measurements of the intercalation of ethidium bromide. We have shown that 50% of the nucleotides of 70
S
RNA in solution are in a stable helical configuration. This value does not include small helical regions that are too unstable to permit intercalation of the dye. The avian myeloblastosis virus RNA as it exists within the virion has the same degree of helicity as the free 70
S
RNA. Heating the free 70
S
RNA to 55 or 70 C, followed by cooling, does not measurably change the degree of helicity; the subunits therefore have as much helicity as the parent molecule.
Mixed Infections of
Bacillus subtilis
Involving Bacteriophages SP82 and β22
Authors: Whiteley H. R. , Kolenbrander P. E. , Hemphill H. E.
Published: January 2020

Progeny yields and the synthesis of nucleic acids have been investigated in two strains of
Bacillus subtilis
mixedly infected with two unrelated phages, SP82 and β22. When
B. subtilis
strain 168 was the host, the first phage added dominated the infection; when
B. subtilis
strain SB11 was the host, β22 produced progeny even when added to cells 5 min after infection with SP82. Dominance in these mixed infections could be correlated with qualitative and quantitative differences in the synthesis of phage-specific RNAs.
Mechanistic Independence of Avian Myeloblastosis Virus DNA Polymerase and Ribonuclease H
Authors: Brewer Lorraine C. , Wells Robert D.
Published: January 2020

Differential inhibition conditions were established for the DNA polymerase and RNase H activities of avian myeloblastosis virus (AMV) with ether-disrupted AMV and a purified enzyme preparation. The RNase H activity of ether-disrupted AMV with (rA)
n
·(dT)
n
and (rA)
n
·(dT)
11
as substrates was inhibited 80 to 100% by preincubation with NaF at a final reaction concentration of 27 to 30 mM. Under these conditions, the DNA polymerase activity was inhibited only 0 to 20%. Similar inhibitions were found with exogenous Rous sarcoma virus 35
S
and 70
S
RNA·DNA hybrid and φX174 DNA·RNA hybrid as substrates. Studies were also performed with a purified enzyme preparation, in which the two activities essentially co-purified. The RNase H activity was inhibited >80% by 150 mM KCl with three different hybrid substrates, whereas the DNA polymerase activity was uninhibited. The DNA polymerase was completely inactivated by heat denaturation at 41 C or by omission of the deoxytriphosphates from the reaction mixture; the RNase H remained active. These differential inhibition conditions were used to compare the size of the DNA product synthesized with and without simultaneous RNase H action and to examine the effect of inhibition of the DNA polymerase on the size of the RNase H products. The size of the products of one activity was not affected by inhibition of the other activity. These results suggest that the AMV DNA polymerase and RNase H are not coupled mechanistically.
Simian Virus 40-Host Cell Interactions II. Cytoplasmic and Nucleolar Accumulation of Simian Virus 40 Virion Protein
Authors: Widmer Chantal , Robb James A.
Published: January 2020

We have used immunofluorescence in parallel with transmission and scanning electron microscopy to characterize the unusual cytoplasmic and nucleolar accumulation of Simian virus 40 (SV40) virion protein (C antigen) at restrictive temperatures (39 to 41 C) in monkey cells infected with a temperature-sensitive mutant of SV40 defective in virion assembly,
tsB11
. Cytoplasmic and nucleolar accumulation of C antigen did not occur in wild-type-infected cells at any temperature. Wild-type- and
tsBll
-infected cells were not distinguishable at 33 C by immunofluorescence or electron microscopy. Temperature-shift experiments using metabolic inhibitors of DNA (cytosine arabinonucleoside, 20 μg/ml), RNA (actinomycin D, 5 μg/ml), and protein synthesis (cycloheximide, 2 × 10
−4
to 10 × 10
−4
M) were used to investigate the requirements for ongoing DNA, RNA, and protein synthesis in the distribution of virion protein between the nucleus, nucleolus, and cytoplasm. The transport of C antigen from the nucleolus and cytoplasm into the nucleus was complete after a temperature shift-down (41 and 39 to 33 C). Limited virus particle formation occurred after the shift-down in the presence of actinomycin D and cycloheximide, indicating some of the 39 to 41 C synthesized virion protein could be used for capsid assembly at 33 C in the absence of further virion protein synthesis. Nucleolar and cytoplasmic accumulations of C antigen occurred in the absence of drugs after a shift-up (33 to 39 C and 41 C) indicating a continuous requirement for the
tsB11
mutant function. Furthermore, the virion protein synthesized at 33 C remained confined to the nucleus when the cells were shifted to 39 and 41 C in the presence of actinomycin D or cycloheximide. In the presence of cytosine arabinonucleoside, however, the virion protein accumulated in large aggregates in the nucleus and nucleolus after the shift-up, but did not migrate into the cytoplasm as it did in drug-free
tsB11
-infected control cells. Colchicine (10
−3
M) had no effect on the abnormal accumulation of C antigen during shift-up or shift-down experiments suggesting that microtubular transport plays little if any role in the abnormal transport of
tsB11
virion protein from cytoplasm to nucleus. Although virus particles were never observed by electron microscopy and V antigen was not detected by immunofluorescence at 39 or 41 C in
tsB11
-infected cells, dense amorphous accumulations were formed in the nucleoli and cytoplasm. We suggest that the
tsB11
function is continuously required for the normal transport of SV40 virion protein between the cytoplasm, nucleolus, and nucleus and for the assembly of capsids and virions. Several possible mechanisms for the altered
tsB11
function or protein are discussed. One of the virion proteins may also be involved in some presently undetermined nucleolar function during SV40 productive infection.
Murine Type-C Virus Group-Specific Antigens: Interstrain Immunochemical, Biophysical, and Amino Acid Sequence Differences
Authors: Oroszlan Stephen , Summers Murray R. , Foreman Carol , Gilden Raymond V.
Published: January 2020

The 30,000-molecular-weight internal protein, p30, was purified from seven strains of mouse type-C viruses. The individual p30's showed variation in isoelectric points and also intrastrain heterogeneity. The individual p30's could be distinguished by peptide map and quantitative complement fixation techniques with relatedness estimates of >95%. Amino terminal sequence analysis showed variability at position 4 for several p30's with complete homology otherwise through 24 residues. The intrastrain heterogeneity in p30 isoelectric points could not be explained by common contaminants, as shown by peptide mapping, and is more likely based on post-transcriptional modifications. These data provide a chemical basis for the recently described type-specific immunological properties of individual p30's.
Plaque Formation with Simian Virus 40: Enhancement by Dimethyl Sulfoxide
Authors: Cleaver James E.
Published: January 2020

Dimethyl sulfoxide (DMSO) added to agar overlays during plaque assays of simian virus 40 (SV40) in CV1 monkey cells increases the plaque size and number and enables plaques to be read several days earlier than usual. DMSO appears to act during development of plaques, perhaps by causing cell lysis at smaller burst sizes in the presence of near-lethal DMSO concentrations. It does not act synergistically in determining virus inactivation with UV light and is equally effective on wild type and a late mutant of SV40.
Bacteriophage transformation of PBS2 in Bacillus subtilis
Authors: Herrington M B , Takahashi I
Published: January 2020

Transformation of temperature-sensitive mutants of bacteriophage PBS2 for Bacillus subtilis was demonstrated. The number of transformants was linearly related to the concentration of DNA within a range of 0.01 to 1 mug/ml. No transformants were obtained when the DNA was pretreated with DNase. PBS2 DNA sheared to approximately 1% of the total chromosome length was centrifuged in Cs2SO4-Hg gradients to fractionate the DNA according to the base composition. Transformation experiments carried out with the fractionated DNA indicated the possibility of determining the base composition of different regions of the phage chromosome.
Host DNA Degradation after Infection of
Escherichia coli
with Bacteriophage T4: Dependence of the Alternate Pathway of Degradation Which Occurs in the Absence of Both T4 Endonuclease II and Nuclear Disruption on T4 Endonuclease IV
Authors: Parson Kathleen A. , Snustad D. Peter
Published: January 2020

Escherichia coli
cells infected with T4 phage which are deficient in both nuclear disruption and endonuclease II exhibit a pathway of host DNA degradation which does not occur in cells infected with phage deficient only in endonuclease II. This alternate pathway of host DNA degradation requires T4 endonuclease IV.
Temporal appearance of bacteriophage T4-modified valyl tRNA synthetase in Escherichia coli
Authors: Müller U R , Marchin G L
Published: January 2020

Bacteriophage T4-induced modification of Escherichia coli vlayl-tRNA synthetase (EC 6.1.1.9) requires: synthesis of a phage-gene specified tau factor, addition of the factor to host valyl-tRNA synthetase to produce a urea-stable enzyme, and interaction of the modified enzyme with tRNA to produce a more rapidly sedimenting valyl-tRNA synthetase activity on sucrose density gradients. This report demonstrates that the coincident, chloramphenicol-sensitive appearance of urea-stable and rapidly sedimenting valyl-tRNA synthetase activity are immediate early phage functions. It implies that once the tau factor is synthesized, further interactions are stoichiometric rather than catalytic. The potential for valyl-tRNA synthetase modification accumylates when E. coli is infected with T4 PHAGE IN THE PRESENCE OF CHLORAMPHINICOL AND IS EXPRESSED DURING THE RESUMPTION OF PROTEIN SYNTHESIS WHEREAS FURTHER RNA synthesis is inhibited by rifampicin. The modification phenomenon occurs similarly in several strains of E. coli and represents a novel virus-host interaction.
Stimulation of non-histone chromosomal protein synthesis in simian virus 40-infected simian cells
Authors: Iida H , Oda K
Published: January 2020

The pattern of synthesis of non-histone chromosomal proteins in simian virus (SV) 40-infected African green monkey kidney cells was analyzed by polyacryl-amide gel electrophoresis to see whether the changes in chromosomal protein metabolism are involved in the viral-induced synthesis of cellular DNA and mRNA. During the prereplicative phase of infection, the rate of histone synthesis was decreased until 15 h postinfection, whereas that of non-histone protein synthesis was increased after 5 h postinfection and reached a maximum at 10 to 15 h postinfection when viral-induced synthesis of cellular DNA and mRNA began to be observed. Stimulation of non-histone protein synthesis was also observed in the infected cells treated with cytosine arabinoside and was dependent on the multiplicity of infection. Stimulation occurred in almost all species of non-histone proteins. These results suggest that the stimulation of non-histone protein synthesis is caused by an early SV40 function and occurs prior to the viral-induced synthesis of cellular DNA and mRNA. During the replicative phase of infection, a marked increase in the rate of synthesis was observed in the non-histone proteins with molecular weights of about 48,000, 35,000, and 23,000, which were subsequently found to be SV40 capsid proteins.
Agglutination of Japanese encephalitis virus with concanavalin A
Authors: Yoshinaka Y , Shiomi T
Published: January 2020

Results of experiments have indicated that reduction in biological activities at high concentrations of Japanese encephalitis virus is caused by aggregates of the virus by concanavalin A. The possibility exists that the concanavalin A binding site is different from hemagglutination and antireceptor sites of Japanese encephalitis virus.
Protein metabolism during the steady state of Newcastle disease virus infection. I. Kinetics of amino acid and protein accumulation
Authors: Hightower L E , Bratt M A
Published: January 2020

Pulse-chase experiments and studies on the effects of varying pulse lenghts on radioactive amino acid and protein accumulation have been carried out to evaluate several possible mechanisms for the inhibition in cellular protein accumulation during infection of chicken embryo cells by Newcastle disease virus. The inhibition is probably at the level of synthesis of cellular protein since no evidence for either increased degradation of protein or alterations in cellular permeability to protein was found in infected cultures. The magnitude of the reduction in the rate of cellular protein accumulation and consequently total protein accumulation depend upon the length of the radioisotopic labeling period. In contrast, the rate of viral protein accumulation is independent of the length of the labeling period. A double-label difference analysis of polyacrylamide gels was used in all of the kinetics studies to distinguish between viral and cellular protein accumulation. An unstable fraction which could be labeled with radioactive amino acids was detected in both infected and uninfected cultures. This material migrated mainly in the 50,000- to 60,000-dalton region of polyacrylamide gels, exhibited saturation kinetics during accumulation studies, and turned over rapidly during a chase. The relative amount of this fraction was not affected by infection. Gel analysis of the radioactive protein recovered from the medium from both infected and uninfected cultures revealed a major component with an apparent molecular weight of 33,000. None of the major viral polypeptides could be detected in the medium after a 30-min chase following a brief labeling period.
Bacteriophage-host interaction and restriction of nonglucosylated T6
Authors: Hewlett M J , Mathews C K
Published: January 2020

Nonglucosylated T6 phage (T6gtam 16am30, hereafter called T6alpha gt-) were found to have two structural anomalies when compared with wild-type T6. The DNA of T6alpha gt- phage contains single-strand interruptions. These can be seen both during infection, in the pool of replicating DNA, and in DNA extracted from purified phage. In addition, the sodium dodecyl sulfate-polyacrylamide gel pattern of T6alpha gt- phage structural proteins reveals a protein band not found in T6. The altered protein has a mobility slightly faster than that of the major head protein, and it is not removed by osmotic shock. The restriction activity of Escherichia coli B directed against T6alpha gt- phage is abolished by preinfection of the cells for 4 min with T4 im m2. The shut-off of restriction is observed either by the rescue of superinfecting T6alpha gt- or by the failure to detect degradation of incoming T6alpha gt- DNA. This effect is resistant to rifampin and chloramphenicol.
Nucleotide sequence complexities, molecular weights, and poly(A) content of the vesicular stomatitis virus mRNA species
Authors: Rose J K , Knipe D
Published: January 2020

Poly(A)-containing vesicular stomatitis virus mRNA species synthesized in vesicular stomatitis virus-infected cells have been separated into four bands by electrophoresis on formamide-polyacrylamide gels. Two-dimensional fingerprints of ribonuclease T-1 and ribonuclease A digests of the RNA from each band show that they contain unique oligonucleotide sequences as well as 60 to 125 nucleotides of poly(A). The fingerprints were used to determine the nucleotide sequence complexities of RNA from three of the bands. Two contain nucleotide sequences which account completely for their molecular weights (0.70 times 10-6 and 0.55 times 10-6) determined by gel electrophoresis and sedimentation rate, and, therefore, these are radiochemically pure RNA species. The most rapidly migrating band must contain two ro three different RNA species since it has a molecular weight of 0.28 times 10-6, determined by physical methods, and a nucleotide sequence complexity two to three times that expected for a pure RNA species of this size. These data are in complete accord with translational studies (accompanying paper) which show that each of the two pure RNA species codes for a distinct viral protein, whereas the third codes for two viral proteins. From the molecular weight and sequence complexity determinations on mRNA from the bands, we conclude that most of the vesicular stomatitis virus genome is transcribed into discrete mRNA species.
Genetic Analysis of Adenovirus Type 2 II. Preliminary Phenotypic Characterization of Temperature-Sensitive Mutants
Authors: Weber J. , Begin M. , Khittoo G.
Published: January 2020

The properties of temperature-sensitive mutants of adenovirus type 2 representing 12 complementation groups were studied. All mutants were normal with respect to adsorption as measured by viral inclusion formation and viral DNA synthesis as shown by velocity sedimentation in alkaline sucrose gradients. One mutant, however, formed viral inclusions of altered morphology at the nonpermissive temperature. The synthesis of the major capsid proteins was examined by immunodiffusion. On this basis, the complementation groups could be arranged as follows: (i) one group was negative for all three proteins; (ii) three groups failed to synthesize penton bases; (iii) eight groups were positive for hexons, pentons, and fibers. The assembly of virus particles at 39 C was examined by equilibrium sedimentation in CsCl; three groups were found defective, whereas two of the penton-negative groups were positive for virion production. Tests of the thermolability of virions at 50 C revealed eight groups labile whereas the remainder were insensitive to heat inactivation. None of five mutants inoculated in newborn rats induced tumors, although three of them were capable of in vitro transformation.
Chromatographic Separation and Antigenic Analysis of Proteins of the Oncornaviruses IV. Biochemical Typing of Murine Viral Proteins
Authors: Buchhagen D. L. , Stutman O. , Fleissner E.
Published: January 2020

Tryptic peptide maps were prepared for four purified structural proteins derived from several murine leukemia viruses (MuLV's). Analyses of these peptide maps reveal that the p30 proteins of Rauscher, Moloney, and Gross MuLV's are very similar to each other, as are the p10's obtained from these three viruses. In contrast, the peptide maps of the individual p15's and p12's from the same viruses establish that each of these polypeptides is highly strain specific. For all four polypeptides studied, unique peptides appear in the Rauscher MuLV and Moloney MuLV tryptic profiles that are not present in the corresponding Gross MuLV profile. By this method of analysis it was possible to distinguish the p30's of N-tropic and B-tropic MuLV's derived from the same BALB/c mouse.
Simian Virus 40 DNA Segment of the Adenovirus 7-Simian Virus 40 Hybrid, E46
+
, and Its Transcription During Permissive Infection of Monkey Kidney Cells
Authors: Lebowitz Paul , Khoury George
Published: January 2020

Nucleic acid hybridization methodology has been used to investigate the span of the simian virus 40 (SV40) DNA segment in the adenovirus 7-SV40 hybrid, E46
+
, and the extent of its transcription in lytically infected monkey kidney cells. The SV40 segment of E46
+
comprises approximately 62% of the SV40 genome; it originates in the proximal region of
Hin-G
(the
G
fragment derived by cleavage of intact SV40 DNA with
Haemophilus influenzae
restriction endonuclease), extends sequentially through approximately 80% of this fragment, all of fragments
Hin-B, -I, -H
, and
-A
, and terminates approximately 70% of the distance through
Hin-C
. During E46
+
lytic infection of permissive cells, the vast majority of stable cytoplasmic SV40-specific RNA is transcribed from the minus (E) strand of the fragments
Hin-A, -H, -I
, and
-B
, comprising the early template region. Transcripts of the minus strand of the
Hin-G
and
-C
fragments are detected in much lower concentrations, especially in the total lytic cellular RNA, whereas RNA complementary to the plus (L) strand is not detected. The transcriptional pattern of the SV40 segment within E46
+
is thus very similar to that in a number of transformed cell lines and in some respects to the transcriptional pattern in a series of nondefective adenovirus 2-SV40 hybrid viruses. These results suggest a common transcriptional mechanism for integrated SV40 DNA.
Heteroduplex Mapping of Heat-Resistant Deletion Mutants of Bacteriophage T5
Authors: Scheible Patricia P. , Rhoades Marc
Published: January 2020

The bacteriophage T5 is known to spontaneously generate deletion mutants (
st
mutants) exhibiting enhanced resistance to heat inactivation in citrate buffer. A series of such mutants has been isolated and the deletions visualized by electron microscopy of heteroduplex molecules. The deletions are found to cluster in one region of the chromosome.
Presence of herpes simplex virus-related antigens in transformed L cells
Authors: Chadha K C , Munyon W
Published: January 2020

Antiserum prepared against herpes simplex virus type 1 (HSV-1)-infected L cells, i.e., lytic antiserum, was shown by an indirect immunofluorescence test to stain 90 percent of HSV-transformed L or HeLa cells. Immunofluorescence in these cells was always most intense in the perinuclear cytoplasmic region. Similar results were obtained with antiserum prepared against HSV-transformed L cells. These data indicate that HSV-transformed cells (both L and HeLa) express HSV-related antigens. Antiserum prepared against HSV-1-transformed L cells, i.e., transformed-cell antiserum, was found to agglutinate purified HSV type 1 virions but failed to neutralize infectivity. This suggests that HSV-1 structural antigens are expressed in HSV-1-transformed L cells. Immunodiffusion studies showed that at least two HSV-related antigens could be demonstrated with antigens from HSV-1-transformed L cells and transformed-cell antiserum. These two antigens were shown to be present in all clonal lines of HSV-1-transformed cells examined, six L cell lines and one HeLa cell line. Therefore, we conclude that transformation of cells by HSV-1, which is known to be associated with acquisition of viral thymidine kinase, must also be associated with the presence of these two antigens. We performed experiments showing that there are species of HSV-related antibody in HSV-transformed cell antiserum that could not be absorbed out with antigens from HSV-infected L cells. Antibodies present in lytic antiserum were completely removed by antigen preparations from cells lytically infected with HSV-1. Also, lytic antiserum failed to block HSV-related staining of transformed L cells in a direct immunofluorescence test. These results are compatible with one of two notions: either (i) certain genes are expressed during transformation that are not expressed during lytic infection, or (ii) these genes are expressed to a much more reduced extent during lytic infection than in transformed cells.
Control of thymidine kinase synthesis in IHD vaccinia virus-infected thymidine kinase-deficient LM cells
Authors: Zaslavsky V , Yakobson E
Published: January 2020

The synthesis of vaccinia virus-induced thymidine kinase is normally arrested several hours after infection. In thymidine kinase-deficient LM cells infected with IHD strain of vaccinia virus, arrest occurs whether or not viral DNA synthesis is inhibited. With virus inactivated by UV irradiation, enzyme synthesis takes place, but arrest is abolished. It is suggested that an early viral genetic function is responsible for the cessation of thymidine kinase synthesis.
Presence of active polyribosomes in bacterial cells infected with T4 bacteriophage ghosts
Authors: Takeishi K , Kaji A
Published: January 2020

Host protein synthesis of Escherichia coli stops abruptly after T4 bacteriophage ghost infection. When infection was carried out in the presence of 10 mM Mg2plus, infected cells still have active polyribosomes despite the complete stoppage of protein synthesis. On the other hand, when T4 ghost infection was carried out in the presence of 1 mM Mg2plus, no polyribosomes were observed and most of the ribosomes were 30S and 50S subunit particles. Subunits obtained from extracts of ghost-infected cells at 1 mM M'G2++ concentration could not be converted to polyribosomes, even when Mg2plus concentration was adjusted to 10 mM after ghost infection. There was very little difference in amino acid incorporation activities between polyribosomes from ghost-infected and uninfected cells. In addition, the activity of 70S ribosomes isolated from uninfected cells was identical to that from cells infected with ghosts at 10 mM Mg2plus.
Fate of polyoma form IDNA during replication
Authors: Roman A , Dulbecco R
Published: January 2020

The fate of polyoma form IDNA generated during replication was investigated in resting BALB-3T3 cells. The experiments showed that there was extensive re-entry of such molecules into replication. This process took place over a period of several hours and appeared to be random. Progeny form I molecules must, therefore, spend some time in a nonreplicating pool before reinitiating replication. We propose that two factors affect the fate of progeny form IDNA. (i) The rate of reinitiation of progeny molecules is determined by the capacity of the initiation machinery. (ii) The extent of re-entry is determined by the availability of maturation proteins which divert form I from replication.
Mitosis is required for production of murine leukemia virus and structural proteins during de novo infection
Authors: Fischinger P F , Tuttle-Fuller N , Hüper G , Bolognesi D P
Published: January 2020

Cloned 3T3FL cells were synchronized in G1 phase of the cell cycle by deprivation of multiplication stimulatory activity of serum and were then infected with Moloney leukemia virus. Eclipse period of virus could be made to vary from less than 10 to 34 h. All virus release was completely dependent and occurred immediately after the first mitosis following serum reconstitution. Virus yield was not affected by the time of virus inoculation as related to the cell DNA synthetic phase. Colchicine arrested the cells in mitosis and prevented the formation of infectious virus. Viral proteins p10, p30, and gp71 were assayed in cell lysates during the growth curve of virus in synchronized cells. The group-specific determinants of each protein were measured in a competition radioimmunoassay. None of the virus proteins appeared during the eclipse period of the virus. All three proteins appeared simultaneously, coincident with mitosis, and continued to rise during the G1 phase. The absolute quantities of each protein were proportional to the amount of Moloney leukemia virus produced. The relative amounts of some of the viral proteins in the cell did not correspond to their content in purified virions suggesting several possible mechanisms of control.
Interaction of P2 bacteriophage with the dnaB gene of Escherichia coli
Authors: Sunshine M , Usher D , Calendar R
Published: January 2020

The dnaB gene product of Escherischia coli is required for multiplication of temperate phage P2. At 37 C in dnaB-ts mutnats, P2 will not plaque and gives a very small burst of progeny. P2 mutants have been isolated which can grow well enough to plaque under these conditions. This type of phage mutant is cis dominant, and one such mutant (P2rlb1) has been mapped near the left end of the early gene B and to the right of the cox4 (excision) mutation. The rlb1 mutation does not lie at the replication origin, but may affect transcription in the early region, which includes the replication origin. It may also represent a site on the P2 DNA which interacts with the dnaB gene product.
Synthesis of complex forms of bacteriophage phiX174 double-stranded DNA in a temperature-sensitive dnaC mutant of Escherichia coli C
Authors: Kranias E G , Dumas L B
Published: January 2020

Fast-sedimenting forms of bacteriophage phiX174 double-stranded replicative-form DNA observed in normal infections continued to accumulate at the nonpermissive temperature in a temperature-sensitive dnaC mutant of Escherichia coli. These complex molecules accounted for up to half of the DNA synthesized during short pulses at the nonpermissive temperature. They were the dead-end products of DNA synthesis, not intermediates in normal replicative-form replication. The data suggest that these higher-than-normal-molecular-weight DNA molecules result from abnormal initiation of phiX174 replicative-form DNA replication.
Polyacrylamide gel electrophoresis of intact bacteriophage T4D particles
Authors: Childs J D , Birnboim H C
Published: January 2020

A method for the electrophoresis of intact bacteriophage T4D particles through polyacrylamide gels has been developed. It was found that phage particles will migrate through dilute polyacrylamide gels (less than 2.1%) in the presence of a low concentration of MgCl2. As few as 5 x 10(9) phage particles can be seen directly as a light-scattering band during the course of electrophoresis. The band can also be detected by scanning gels at 260 to 265 nm or by eluting viable phage particles from gel slices. A new mutant (eph1) has been identified on the basis of its decreased electrophoretic mobility compared with that of the wild type; mutant particles migrated 14% slower than the wild type particles at pH 8.3 and 35% slower at pH 5.0. The isoelectric points of both the wild type and eph1 mutant were found to be between pH 4.0 and 5.0. Particles of T4 with different head lengths were also studied. Petite particles (heads 20% shorter than normal) migrated at the same rate as normal-size particles. Giant particles, heterogenous with respect to head length (two to nine times normal), migrated faster than normal-size particles as a diffuse band. This diffuseness was due to separation within the band of particles having mobilities ranging from 8 to 35% faster than those of normal-size particles. These observations extend the useful range of polyacrylamide gel electrophoresis to include much larger particles than have previously been studied, including most viruses.
Endonuclease R-EcoRII restriction of bacteriophage f1 DNA in vitro: ordering of genes V and VII, location of an RNA promotor for gene VIII
Authors: Vovis G F , Horiuchi K , Zinder N D
Published: January 2020

Replicative form DNA of bacteriophage f1 was found to be sensitive in vitro to restriction by endonuclease R-EcoRII if the DNA was isolated from an Escherichia coli strain deficient in cytosine methylase activity. A similar observation was previously made with DNA from the closely related bacteriophage fd (S. Schlagman, S. Hattman, M. S. May, and L. Berger, submitted for publication). The two DNA fragments produced by the endo R-EcoRII digestion of f1 DNA were localized on the f1 cleavage map and their genetic content was determined. The polypeptides synthesized in a "coupled" transcription-translation system under the direction of each RII fragment were examined. The results of such experiments allow the ordering of genes V and VII and indicate the location of a RNA promotor for gene VIII.
Comparative ultrastructural study of four reticuloendothelias viruses
Authors: Kang C Y , Wong T C , Holmes K V
Published: January 2020

The morphology and development of four members of the reticuloendotheliosis virus group were studied by transmission electron microscopy. Virions of duck spleen necrosis virus, duck infectious anemia virus, chicken syncytial virus, and reticuloendotheliosis virus strain T are sperical with a diameter of approximately 110 nm. They are covered with surface projections about 6 nm long and 10 nm in diameter. The center-to-center distance of surface projections is about 14 nm. The budding virions contain crescent-shaped electron-dense cores 73 nm in diameter with electron-lucent centers. After release of the virions the cores apparently become condensed to 67 nm in diameter. Virions were found budding at the plasma membrane and into smooth-walled, intracytoplasmic vesicles of productively infected cells. The distribution of budding reticuloendotheliosis viruses on cells appeared random over the cell surface, and occasionally aberrant multiple forms of budding virions were observed. The virions appear to resemble mammalian leukemia and sarcoma viruses more closely than avian leukosis-sarcoma viruses.
Sindbis virus inhibits phosphatidylcholine biosynthesis in BHK-21 cells
Authors: Vance D E , Lam J
Published: January 2020

Sindbis virus inhibits the incorporation of [methyl-3H]choline into the phospholipids of BHK-21 cells and also inhibits the activity of the enzyme that catalyzes the final reaction involved in phosphatidylcholine biosynthesis (cytidine diphosphate-choline:1,2-diacylglycerol cholinephosphotranferase; EC 2.7.8.2).
Fate of MS2 proteins synthesized in Escherichia coli exposed to amino acid analogues
Authors: Prouty W F
Published: January 2020

Incorporation of an analoque into MS2 coded proteins prevents the maturation of phages. In addition, there is an alteration in the relative amount of coat protein to replicase protein synthesized, which supports the hypothesis that normal coat protein serves a physiological role as a translation repressor. Further, abnormal proteins, synthesized from the phage genome, are degraded, presumably by a host catabolic system, more rapidly than the normal gene products.
Phospholipase activity in bacteriophage-infected Escherichia coli. III. Phopholipase A involvement in lysis of T4-infected cells
Authors: Hardaway K L , Maten M V , Buller C S
Published: January 2020

Bacteriophage studies with Escherichia coli K-12 (gamma)DR-DS-, a mutant lacking the major known fatty acyl hydrolases (phospholipases), and its wild-type parent showed equivalent phage infection with regard to phage production and time of phage release. Further examination of the DR-DS- mutant, however, revealed that the progeny bacteriophage were released without complete dissolution of the host cell. Prolonged cell integrity of the infected mutant was noted by spectrophotometry and supported by direct microscope examination. The phage release occurred at normal "lysis" time with phage yields comparable to that of the wild-type bacteria. Inner membrane degradation was indicated by the release of beta-galactosidase, a cytoplasmic enzyme, and of trichloracetic acid-precipitable RNA. Thus, outer membrane degradation is required for dissolution of phage-infected cells, and this degradation is at least partly dependent on activation of host phospholipases.
Characterization of endogenous RNA-directed DNA polymerase activity of reticuloendotheliosis viruses
Authors: Kang C Y
Published: January 2020

Reticuloendotheliosis viruses (REV) contain an endogenous RNA-directed DNA polymerase activity. The endogenous DNA polymerase activity can be elicited in purified preparations of REV by treatment with nonionic detergents. The enzyme activity has a strong preference for manganous ions. Therefore, appreciable endogenous DNA polymerase activity can be demonstrated only if the reaction mixture contains appropriate concentrations of manganous ions. Enzyme activity can be inhibited by pretreatment with RNase or deletion of one or more deoxyribonucleoside triphosphates from the reaction mixture. In contrast, actinomycin D has little effect in initial DNA synthesis. The results from both velocity and equilibrium centrifugation indicate that the nascent chains of product DNA are associated with 60S viral RNA. The DNA product of the endogenous DNA polymerase reaction is hybridizable to REV RNA, but not to avian leukosis virus RNA.
Simian virus 40 integration sites in the genome of virus-transformed mouse cells
Authors: Prasad I , Zouzias D , Basilico C
Published: January 2020

To gain information on the specificity of simian virus 40 (SV40) integration in the genome of transformed cells, mouse 3T3 cells were transformed by a temperature-sensitive (ts) SV40 mutant, using high multiplicity of infection (MOI). Transformed cells were superinfected with wild-type (wt) virus at high MOI. Clones were isolated and fused with permissive BSC-1 cells to promote virus rescue. All rescued viruses were of the ts type only. When the high-MOI transformants were infected with 3H-labeled wt SV40, the amount of radioactivity associated with their nuclear fraction was found to be similar to that of 3T3 cells. 3T3 cells were then transformed by ts SV40 at low MOI and superinfected by wt virus at high MOI. Upon fusion with BSC-1 cells, most clones produced both ts and wt virus. These results suggest that the number of stable SV40 integration sites in the 3T3 genome is limited, since they can be saturated by transformation at high MOI. When the MOI is low, the sites are not saturated and a subsequent infection can lead to integration.
Morphogenesis of Sindbis virus in cultured Aedes albopictus cells
Authors: Gliedman J B , Smith J F , Brown D T
Published: January 2020

Cultured mosquito cells were found to produce Sindbis virus nearly as efficiently as BHK-21 cells at 28 C. In virtually all of the cells observed in the electron microscope, virus morphogenesis was found to occur within complex vesicular structures which developed after viral infection. Viral nucleocapsids were first seen in these vesicles and appeared to be enveloped within these structures. The process of envelopment within these inclusions differed in some respects from the process previously described for the envelopment of nucleocapsids at the plasma membrane of vertebrae cells. Free nucleocapsids were only rarely seen in the cytoplasm of infected mosquito cells, and budding of virus from the cell surface was detected so infrequently that this process of virus production could not account for the amount of virus produced by the infected cells. The vast majority of extracellular virus was produced by the fusion of the virus-containing vesicles with the plasma membrane releasing mature virions and membrane nucleocapsid complexes in various stages of development.
Molecular structure of human fibroblast and leukocyte interferons: probe by lectin and hydrophobic chromatography
Authors: Jankowski W J , Davey M W , O'Malley J A , Sulkowski E , Carter W A
Published: January 2020

Structural differences between human leukocyte virus-induced interferon and human fibroblast polyinosinic-polycytidylic acid (rIn-rCn)-induced interferon have been noted in previous studies. This study reports the behavior of human leukocyte and fibroblast interferon, induced by virus and by rIn-rCn, in several lectin and hydrophobic chromatographic systems. Differences in both glycosylation and in hydrophobicity of human leukocyte and fibroblast interferons are documented. Human fibroblast interferon is a glycoprotein, whereas our evidence suggests that human leukocyte interferon probably is not. Also, fibroblast interferon is more hydrophobic than leukocyte interferon, as probed on several hydrophobic adsorbents. The possible relationships of these differences to each other and to antigenic variations are discussed. Generally, the differences appear to be attributable to the cell type in which the interferon was induced. However, our results suggest that at least subtle differences in the processing of the induction signal (virus or rIn-rCn) within the same cell type may occur, slightly altering some structural features.