bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence Against Phenotypic Mixing Between Bacteriophage T4 Wild Type and T4v
−
Authors: Chiang Tom , Harm Walter
Published: January 2020

In a recent publication Shames et al. (1973) concluded that the UV-specific T4 endonuclease (a repair enzyme coded for by the gene
v
of wild-type T4) is a component of extracellular phage, which is injected into the host cell and can perform an early repair step without requiring gene expression. This notion is, however, not supported by results presented in this paper. Lysates obtained from mixed multiple infection of
Escherichia coli
cells with T4
v
1
−
and T4
v
+
(or T4
v
2
−
and T4
v
+
) failed to show the expected phenotypic mixing, i.e., incorporation of UV endonuclease into capsids of
v
−
phages resulting in recognizable repair. The fraction of
v
+
and
v
−
particles in such lysates was determined by single-plaque analysis before and after irradiation with a UV dose at which virtually all survivors are particles having undergone repair. Even though our mixed infection conditions were most favorable for the possible occurrence of phenotypic mixing, none out of several hundred individual plaques from survivors were found to be genotypically
v
−
, whereas 30 were expected in the case that phenotypically mixed
v
−
particles were repaired like T4
v
+
. Our failure to observe phenotypic mixing suggests that the data by Shames et al. reflect intracellular synthesis of endonuclease after phage infection.
Characterization of Temperate Bacteriophages of
Bacillus subtilis
by the Restriction Endonuclease
Eco
RI: Evidence for Three Different Temperate Bacteriophages
Authors: Wilson G. A. , Williams M. T. , Baney H. W. , Young F. E.
Published: January 2020

Temperate bacteriophages of
Bacillus subtilis
were characterized according to host range and digestion of the bacteriophage genome by endonuclease
Eco
RI. The three bacteriophages, φ3T, SPO2, and φ105, were all heteroimmune, and the DNA digests showed dissimilar patterns by agarose-ethidium bromide gel electrophoresis.
Quantitation of Endogenous C-type Virion Production in Several Murine Cell Lines
Authors: Luftig Ronald B. , Mcmillan Paul N. , Gudger Mollie
Published: January 2020

Quantitation by enumeration of virion particles, measurement of absorbancy at 260 nm, and densitometry on sodium dodecyl sulfate-polyacrylamide gels has shown that mouse L-M cells yielded 7- to 10-fold less endogenous C-type virions than the parental lines, L or L929. The previously noted stimulation of L-M cell virion production by a concomitant 10% increase in fetal calf serum concentration (D. A. Kindig, R. Karp, and W. H. Kirsten, 1968), was not observed.
Two Classes of Cytoplasmic Viral RNA Synthesized Early in Productive Infection with Adenovirus 2
Authors: Craig Elizabeth A. , Raskas Heschel J.
Published: January 2020

The RNA sequences and RNA size classes transcribed early in productive infection with adenovirus 2 were analyzed by RNA-DNA hybridization. Two independent procedures demonstrated that early cytoplasmic viral RNA is composed of two sequence classes, class I which is absent or present in greatly reduced quantities at 18 h, and class II which persists throughout the infection. When the sequences in early viral RNA were analyzed by hybridization-inhibition studies, the hybridization of early [
3
H]RNA was inhibited only 50% by RNA from cultures harvested late (18 h) in infection. Liquid hybridizations with radioactive viral DNA confirmed that early RNA includes two classes. Duplex formation of RNA with
32
P-labeled viral DNA was assayed by hydroxylapatite chromatography and resistance to S
1
nuclease digestion. Both methods showed that the cytoplasmic RNA present early in infection annealed 12 to 15% of the viral DNA; late cytoplasmic RNA hybridized 21 to 25% of the DNA. Mixtures of early plus late cytoplasmic RNAs hybridized 30 to 34% of the viral DNA, demonstrating the reduced concentration of early class I RNA in the late RNA preparations. Experiments were performed to correlate class I and class II early RNA with size-fractionated cytoplasmic RNA synthesized early in infection. Fractionation of RNA by gel electrophoresis or sucrose gradient centrifugation confirmed three major size classes, 12 to 15
S
, 19 to 20
S
, and 26
S
. Total cytoplasmic RNA and RNA selected on the basis of poly(A) content contained the same size classes of viral RNA. In standard electrophoresis conditions, the 19 to 20
S
viral RNA could be resolved into two size classes, and the distribution of 12 to 15
S
RNA also indicated the presence of more than one size component. Hybridization-inhibition studies under nonsaturating conditions were performed with 26
S
, 19 to 20
S
, and 12 to 15
S
viral RNAs fractionated by gel electrophoresis. Late RNA inhibited the hybridization of 26
S
RNA only 20%, 19 to 20
S
RNA was inhibited 45%, and 12 to 15
S
RNA was inhibited 50%. When 18 to 19
S
and 12 to 15
S
viral RNAs purified by sucrose gradient centrifugation were similarly analyzed, late RNA inhibited hybridization of 18 to 19
S
RNA 50%, and the annealing of 12 to 15
S
RNA was inhibited 70%.
Temperature-Sensitive Mutants of Vesicular Stomatitis Virus: Comparison of the In Vitro RNA Polymerase Defects of Group I and Group IV Mutants
Authors: Ngan J. S. C. , Holloway A. F. , Cormack D. V.
Published: January 2020

When tested in vitro, certain temperature-sensitive (ts) mutants of vesicular stomatitis virus (VSV) belonging to complementation groups I and IV appear to have defects in the virion-bound polymerase. To obtain further information concerning the nature of these defects, representative mutants were dissociated by the method of S. Emerson and R. Wagner (1972), and their supernatant (S) and pellet (P) fractions were tested for transcriptase activity when combined with the P and S fractions, respectively, of VSV-HR virions. It was found that the S fractions from group I mutants tsW4, 11, 14, 15, and 28 were defective in transcriptase activity, whereas their P fractions were as active as those of VSV-HR. On the other hand, the P fraction derived from virions of the group IV mutant tsW16B showed reduced activity at 25 C and very little activity at 38 C. These results suggest that our group I mutants, like those examined by D. Hunt and R. Wagner (1974), have a defect in the soluble transcriptase enzyme, whereas mutant tsW16B (group IV) has a defect in a sedimentable component required for transcriptase activity, possibly in the ribonucleoprotein template.
Autogenous Immunity to Endogenous RNA Tumor Virus: Differential Reactivities of Immunoglobulins M and G to Virus Envelope Antigens
Authors: Lee J. C. , Hanna M. G. , Ihle J. N. , Aaronson S. A.
Published: January 2020

The autogenous humoral immune response of mice to their endogenous leukemia virus has been examined in terms of the reactivities of individual classes of antibody present in normal B6C3F
1
serum. Whole serum and the immunoglobulin (Ig) M and IgG fractions of serum from animals of different age groups were compared by radioimmune precipitation assays and viral infectivity neutralization assays. Both IgM and IgG fractions were able to precipitate virus, although not as effectively as whole serum. Virus-specific antibody levels, as well as total antibody concentrations in whole serum, appeared to increase with age. Sodium dodecyl sulfate gel electrophoresis analysis was performed with immune precipitates obtained when whole serum or 19 or 7
S
fractions from animals of different age groups were reacted with disrupted virus. The 19
S
antibody fraction reacted with three antigenic determinants on the viral envelope. These antigens have apparent molecular weights of 17,000, 43,000, and 68,000. The last two appear to be glycoproteins and may correspond to the M
2
and M
1
antigens. In contrast, the 7
S
component reacted only with the 17,000-molecular-weight protein. Neutralization assays against BALB:virus-2, a xenotropic endogenous mouse type C virus, revealed that 19
S
and whole serum but not the 7
S
fraction possessed neutralizing activity. These findings indicate that there are differential reactivities of IgM and IgG antibodies in normal serum of B6C3F
1
mice, with respect to both recognition of viral envelope antigens and neutralization of endogenous MuLV. These results are consistent with the hypothesis that the autogenous humoral immune response is a systemic host function that may be important in the regulation of endogenous type C virus expression in vivo.
Analysis of Parvovirus mRNA by Sedimentation and Electrophoresis in Aqueous and Nonaqueous Solution
Authors: Carter Barrie J.
Published: January 2020

Adenovirus-associated virus (AAV)-specific RNA present in the cytoplasm of cells coinfected with a helper adenovirus was analyzed by sucrose gradient sedimentation and gel electrophoresis. In aqueous conditions both gels or gradients revealed three AAV RNA components corresponding to 30
S
, 27
S
, and 20
S
and having apparent molecular weights of 2.6 × 10
6
, 1.75 × 10
6
to 1.8 × 10
6
, and 0.9 × 10
6
to 1.0 × 10
6
, respectively. In nonaqueous, denaturing solvents only the 20
S
AAV RNA species was observed. For this reason, and because they would be apparently significantly larger than a single AAV DNA strand, both the 30
S
and 27
S
species are believed to result from conformational or aggregation effects in the aqueous nondenaturing systems. It is concluded that only a single RNA molecule having a molecular weight of approximately 0.9 × 10
6
to 1.0 × 10
6
is synthesized by AAV.
Reversible Inhibition of Poliovirus RNA Synthesis In Vivo and In Vitro by Viral Products
Authors: Röder Anton , Koschel Klaus
Published: January 2020

In poliovirus-infected HeLa-S3 cells, the protease inhibitors tolylsulfonyl-phenylalanyl chloromethyl ketone and iodoacetamide cause an accumulation of large precursor proteins, and they block viral RNA synthesis most probably via these products. Viral RNA polymerase activity can, however, be extracted by detergent containing buffer (Tris/Nonidet P-40, deoxycholate) from the inhibited cells. Only cytoplasmic extracts from infected cells treated with tolylsulfonyl-phenylalanyl chloromethyl ketone or iodoacetamide contain a protein which inhibits the in vitro polymerase reaction.
Isolation of a λd
v
Plasmid Carrying the Bacterial
gal
Operon
Authors: Berg Douglas E. , Jackson David A. , Mertz Janet E.
Published: January 2020

A λ
dvgal
plasmid carrying genes for controlled plasmid replication from phage λ and the bacterial
gal
operon was isolated as a deletion mutant of phage λ
gal
q4, which carries the
gal
operon between λ genes
P
and
Q
. The plasmid DNA was found in cell extracts as covalently closed circular molecules. The plasmid was characterized by using genetic crosses, digestion with the specific endonuclease
Eco
RI, sucrose gradient centrifugation, and electron microscopy. In one clone analyzed, the plasmid was a complete dimer (
O
λ
P
λ
gal
O
λ
P
λ
gal
); in a subclone derived from it, the plasmid was a partial dimer with only one copy of
gal
(
O
λ
P
λ
O
λ
P
λ
gal
). The partial dimer may be a recombination product of the complete dimer, since test crosses show that the
gal
and λ sequences in the plasmid can be separated by recombination. Analyses of the
Eco
RI digests of plasmid DNAs indicated one cleavage site per λ gene sequence and none in the
gal
operon. A λ
dvgal
monomer was approximately 6.7 × 10
6
daltons and the λ gene and
gal
components were 3.9 × 10
6
and 2.8 × 10
6
daltons, respectively. The λ
dvgal
plasmid can be introduced into a new bacterial host by transfection at an efficiency of 10
−6
per DNA molecule.
Homologous Interference Induced by Sindbis Virus
Authors: Johnston Robert E. , Wan Katherine , Bose Henry R.
Published: January 2020

Homologous interference during Sindbis virus infection has been investigated. Prior infection of either chicken embryo fibroblast or BHK
21
cell cultures results in reduced yields of progeny virions of the superinfecting genotype. This reduction in yield results from a reduction in the number of cells in the cultures capable of producing the superinfecting genotype. The development of interference parallels the attachment kinetics of Sindbis virus. Interference requires an active viral genome since the activity is sensitive to inactivation by ultraviolet light, and an RNA
−
mutant, ts-24, fails to induce interference under nonpermissive conditions. However, ts-6, an RNA
−
mutant belonging to a different complementation group, and the RNA
+
mutants, ts-2 and ts-20, interfere at both permissive and nonpermissive temperatures.
Cell Surface Antigen Induced by Friend Murine Leukemia Virus Is also in the Virion
Authors: Friedman Maureen , Lilly Frank , Nathenson Stanley G.
Published: January 2020

Intact particles of Friend leukemia virus derived from infectious mouse serum absorb only trace amounts of cytotoxic anti-FMR antibodies, but physical disruption of the virions by freezing and thawing, by ether extraction or by detergent treatment releases large amounts of FMR antigenic activity. Thus this antigen, previously considered to occur mainly as a neo-antigen on the surfaces of virus-infected cells and as a soluble substance in the serum of infected mice, may be primarily a virion component.
Effect of Interferon Upon the Primary and Secondary Transcription of Vesicular Stomatitis and Influenza Viruses
Authors: Repik Patricia , Flamand Anne , Bishop D. H. L.
Published: January 2020

The synthesis of viral complementary RNA by vesicular stomatitis virus in permissive cells can be distinguished operationally into two phases, primary transcription, which can be observed in cycloheximide treated cells, and secondary transcription, which represents the further synthesis of viral complementary RNA obtained in untreated cells. Pretreatment of mouse L cells or chicken embryo fibroblasts with the homologous interferon and, for chicken embryo fibroblast cells, poly(rI):poly(rC), inhibits the production of infectious virus and reduces the synthesis of viral complementary RNA to levels comparable to that obtained during primary transcription. Treatment of mouse L cells with interferon plus cycloheximide also gives levels of vesicular stomatitis viral complementary RNA synthesis comparable to that observed with the cycloheximide treatment alone. Similar results have been obtained for interferontreated cells subsequently infected with influenza virus (strain WSN). The results are interpreted as indicating that inhibition of virus development by interferon does not act at the level of primary transcription but rather at an intermediate step between primary and secondary transcription, such as viral protein synthesis.
Marek's Disease Herpesvirus-Induced DNA Polymerase
Authors: Boezi John A. , Lee Lucy F. , Blakesley Robert W. , Koenig Mark , Towle Howard C.
Published: January 2020

Infection of duck embryo fibroblasts by Marek's disease herpesvirus (MDHV), strain GA, led to the induction of a novel DNA polymerase. This novel DNA polymerase, designated MDHV-induced DNA polymerase, could be distinguished from the DNA polymerase activities of uninfected duck embryo fibroblasts by its chromatographic behavior on phosphocellulose, by its sedimentation coefficient, and by its catalytic properties. The characteristics of MDHV-induced DNA polymerase which had been purified by phosphocellulose chromatography were investigated. The sedimentation coefficient of the enzyme, as determined by sucrose density gradient centrifugation in the presence of 0.25 M KCl, was 5.9
S
. From this sedimentation coefficient, the molecular weight of MDHV-induced DNA polymerase was estimated to be 100,000. MDHV-induced DNA polymerase could not effectively use either poly(dA)·oligo(dT)
12-18
or poly(dC)·oligo(dG)
12-18
as a template-primer. The DNA polymerases from uninfected duck embryo fibroblasts could use these synthetic template-primers. MDHV-induced DNA polymerase also could not use poly(rA)·oligo(dT)
12-18
or poly(rC)·oligo(dG)
12-18
as template-primers or oligo(dT)
12-18
as a primer, indicating that it was not a polymerase of the type R-DNA polymerase, reverse transcriptase, or a terminal nucleotidyl transferase. In vitro synthesis of DNA by MDHV-induced DNA polymerase was markedly inhibited by the addition of (NH
4
)
2
SO
4
to the reaction mixture.
Biological Expression of Antigenic Determinants of Murine Leukemia Virus Proteins gp69/71 and p30
Authors: Ikeda H. , Pincus T. , Yoshiki T. , Strand M. , August J. T. , Boyse E. A. , Mellors R. C.
Published: January 2020

Antisera to purified structural proteins of Rauscher murine leukemia virus, the major envelope glycoprotein, gp69/71, and the major internal protein, p30, were studied by immunofluorescence of viable and fixed virus-infected cells and by virus neutralization. Group-specific and type-specific determinants of gp69/71 were demonstrated by immunofluorescence and virus neutralization tests, indicating that these determinants are located in the cytoplasm and probably on the cell surface as well as on virus envelope. Antisera against p30 showed anti-group and anti-interspecies activities by immunofluorescence with no virus-neutralizing activity. Both antigenic determinants of gp69/71 were sensitive to guanidine-hydrochloride and to a lesser degree to ether treatment, whereas the group-specific determinants of p30 were relatively stable to these treatments.
Physiological Study of Cooperative Infection by Restricted Bacteriophage T1
Authors: Potts Thomas V. , Christensen J. R.
Published: January 2020

The ability of certain phages to successfully infect a restricting host at a high multiplicity of infection is known as cooperative infection or cooperation. We have examined the ability of unmodified T1 (T1·0) to participate in cooperative infection in cells possessing the P1 restriction system. We have found that cooperation is dependent upon protein synthesis during the first few minutes after phage infection. However, we have been unable to attribute the necessary protein to a known T1 cistron. Degradation of the restricted T1 genome is approximately equally extensive whether cooperative infection occurs or whether it is blocked by chloramphenicol. It is postulated that an inducible host repair mechanism may be responsible for the phenomenon of cooperative infection.
Characterization of Polyoma DNA-Protein Complexes I. Electrophoretic Identification of the Proteins in a Nucleoprotein Complex Isolated from Polyoma-Infected Cells
Authors: McMillen Janis , Consigli R. A.
Published: January 2020

A study was undertaken to examine polyoma DNA-protein complexes. A biophysical characterization of the complexes was made, and the proteins found in such complexes were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A comparison was made between a 52
S
nucleoprotein complex isolated from nuclei of 26-h polyoma-infected cells and a 28
S
virion core complex ejected out of mature virus particles. It was found that both complexes were reduced to a 20
S
viral DNA component plus free protein after incubation in 1 M NaCl or Sarkosyl. Treatment of the complexes with either Pronase or 0.5 M NaCl resulted in only partial removal of proteins from the viral DNA. After fixation in formaldehyde, the 52
S
nucleoprotein complex had a buoyant density of 1.45 g/cm
3
, and the virion core complex had a buoyant density of 1.59 g/cm
3
. Sodium dodecyl sulfate-polyacrylamide gel profiles of purified polyoma virion proteins, used as a reference marker, demonstrated three capsid proteins, V1 to V3, as well as four histones, V4 to V7, which constituted about 7% of the total virion protein. Electrophoretic analysis of the proteins comprising the 52
S
nucleoprotein complex revealed that the same seven proteins present in the mature virion were also found in this complex. However, the ratios of the proteins in the complex were quite different from that of the mature virion, with the four histones comprising 48% of the total complex protein. A pulse-chase experiment of the nucleoprotein complex demonstrated that the 26-h complex was chased into mature virions.
Bacillus subtilis
DNA Polymerase III Is Required for the Replication of the Virulent Bacteriophage φe
Authors: Lavi Uri , Nattenberg Alona , Ronen Amiram , Marcus Menashe
Published: January 2020

The virulent phage φ
e
of
Bacillus subtilis
which contains hydroxymethyluracil in its DNA requires host DNA polymerase III for its DNA replication. DNA polymerase III
ts
mutant cells infected with φ
e
at restrictive temperatures do not support phage DNA synthesis. However, φ
e
grows normally both at low and high temperatures in the mutant's parent strain and in spontaneous DNA polymerase III
+
revertants isolated from the mutant strain. Temperature-shift-down experiments with φ
e
-infected cells having thermosensitive DNA polymerase III (
pol
III
ts
) indicate that at 48 C the thermolabile DNA polymerase III is irreversibly inactivated and has to be synthesized de novo after the shift to 37 C, before phage DNA synthesis can begin. Temperature-shift-up experiments with φ
e
-infected mutant cells show that phage replication is arrested immediately after the temperature shift and indicate that φ
e
requires DNA polymerase III throughout its replication stage.
Inhibition of Bacteriophage φX174 DNA Replication in
dnaB
Mutants of
Escherichia coli
C
Authors: Dumas Lawrence B. , Miller Christine A.
Published: January 2020

Bacteriophage φX174 DNA replication was examined in temperature-sensitive
dnaB
mutants of
Escherichia coli
C to determine which stages require the participation of the product of this host gene. The conversion of the infecting phage single-stranded DNA to the double-stranded replicative form (parental RF synthesis) is completely inhibited at the nonpermissive temperature (41 C) in two of the three
dnaB
mutants tested. The efficiency of phage eclipse and of phage DNA penetration of these mutant host cells at 41 C is the same as that of the parent host strain. The defect is most likely in the synthesis of the complementary strand DNA. The semiconservative replication of the double-stranded replicative form DNA (RF replication) is inhibited in all three host mutants after shifting from 30 to 41 C. Late in infection, the rate of progeny single-stranded phage DNA synthesis increases following shifts from 30 to 41 C. Approximately the same amounts of phage DNA and of infectious phage particles are made following the shift to 41 C as in the control left at 30 C. The simplest interpretation of our data is that the product of the host
dnaB
gene is required for φX174 parental RF synthesis and RF replication, but is not directly involved in phage single-stranded DNA synthesis once it has begun. The possible significance of the synthesis of parental RF DNA at 41 C in one of the three mutants is discussed.
Isolation and Characterization of Revertant Cell Lines VI. Susceptibility of Revertants to Retransformation by Simian Virus 40 and Murine Sarcoma Virus
Authors: Vogel Arthur , Pollack Robert
Published: January 2020

The susceptibility of two classes of revertants of Simian virus 40 (SV40)-transformed 3T3 cells to retransformation by SV40 or murine sarcoma virus (MSV) was studied. Both serum-sensitive and density-sensitive revertants are not retransformable by SV40. MSV can transform both types of revertants. The MSV-transformed revertants grow to high cell densities and form colonies when suspended in semi-solid methylcellulose medium, but are unable to grow in 1% calf serum. The MSV-transformed revertants produce infectious MSV and murine leukemia virus and possess the same number of chromosomes as the untransformed revertants.
Nature of φX174 Linear DNA from a DNA Ligase-Defective Host
Authors: Miller Lois K. , Sinsheimer Robert L.
Published: January 2020

Linear DNAs have been prepared from φX phage and from φX RF II (double-stranded circular form of φX DNA, formed during infection and nicked in one or both strands) molecules derived from infection at the restrictive temperature of
Escherichia coli ts
7, a host mutant with a temperature-sensitive DNA ligase activity. The linear DNA from these phages can be circularized by annealing with fragments of φX RF DNA produced by the
Haemophilus influenzae
restriction nuclease. The circularization experiment indicated that the site of breakage of the linear phage DNAs is not unique nor confined to a particular region of the genome. These linear DNAs were less than 0.1% as infective as circular phage DNA. The linear, positive strand of late RF II DNA, however, is uniquely nicked in the region of the φX genome corresponding to cistron A. Although a low level of infectivity is associated with the linear DNA derived from late RF II, this infectivity appears to be a result of the association of linear positive and linear negative strands during the infectivity assay.
Replication Process of the Parvovirus H-1 IV. H-1-Specific Proteins Synthesized in Synchronized Human NB Kidney Cells
Authors: Kongsvik John R. , Gierthy John F. , Rhode Solon L.
Published: January 2020

The synthesis of two virus-induced proteins, VP1 (mol wt 92,000) and VP2′ (mol wt 72,000), was detected in the cell and in purified virions from H-1 parvovirus propagated in synchronous cell cultures.
Does Phospholipase Have a Role in Killing and Sodium Dodecyl Sulfate Lysis of T4 Ghost-Infected
Escherichia coli?
Authors: Vander Maten M. , Nelson E. T. , Buller C. S.
Published: January 2020

The activation of
Escherichia coli
phospholipase by T4 ghost attachment was shown not to have a significant role in the killing or in the increased sensitivity of the bacterial cells to lysis by sodium dodecyl sulfate.
Mutations in the new gene stIII of bacteriophage T4B suppressing the lysis defect of gene stII and a gene e mutant
Authors: Krylov V N , Yankovsky N K
Published: January 2020

Mutations of bacteriophage T4B were found which suppress the lysis defect of both gene stII mutants and gene e mutants. The suppressor mutations belong to a new gene, stIII, of phage T4B. Gene stIII is located on the genetic map of T4B between genes stI and e. stIII mutants sometimes form star plaques on Escherichia coli B. The latent period on E. coli 594, but not E. coli B, is shorter with stIII mutants than that with wild-type phage. The premature lysis of E. coli 594 infected with stIII phage does not depend on the expression of both stII+ and e+ function. StIII allele is dominant over the stIII+ with respect to both the ability to suppress the stII defect and the early lysis of infected E. coli 594 cultures.
Transcription of the genome of adenovirus type 12. I. Viral mRNA in abortively infected and transformed cells
Authors: Ortin J , Doerfler W
Published: January 2020

In baby hamster kidney (BKH-21) cells abortively infected with adenovirus type 12, polysome-associated, virus-specific RNA could be detected starting 5 to 7 h after infection. The amount of this RNA reached a maximum between 10 to 12 h after infection and continued to be synthesized at a reduced level until late in infection (48 to 50 h.). In BHK-21 cells transformed by adenovirus type 12 (HB cells), 0.26% of the polysome-associated mRNA was virus specific. The size of the virus-specific mRNA isolated from polysomes of BHK-21 cells abortively infected with, or transformed by adenovirus type 12 was determined by electrophoresis in polyacrylamide gels in 98% formamide, i.e., under conditions which eliminated secondary structure or aggregation of RNA. In abortively infected hamster cells viral mRNA size classes of molecular weights 0.9 times 10-6 and 0.65 times 10-6 to 0.67 times 10-6 were predominant. A minor fraction of 1.5 times 10-6 daltons was consistently found and increased with time after infection. Late after infection (24 to 26 h), viral mRNA of 1.9 times 10-6 daltons was also observed. The size distribution of adenovirus type 12-specific mRNA from transformed hamster cells (HB line) was very similar to that in abortively infected cells, except that the relative amount of the viral mRNA fraction of 1.5 times 10-6 daltons was much higher. It is uncertain whether the viral mRNA of high-molecular-weight represents mixed transcripts derived from integrated viral genomes and adjacent host genes.
Temperature-sensitive virus derived from BHK cells persistently infected with HVJ (Sendai virus)
Authors: Kimura Y , Ito Y , Shimokata K , Nishiyama Y , Nagata I
Published: January 2020

BHK-HVJ cells, a cell line of baby hamster kidney cells persistantly infected with HVJ (Sendai virus), started to produce infectious virus by shifting down the incubation temperature from 38 to 32 C. The virus derived from BHK-HVJ cells, designated as HJV-pB, was effectively neutralized with antibody against wild-type virus (HVJ-W) which was used for the establishment of BHK-HVJ cells. HVJ-pB replicated in eggs at 32 C, but not at 38 C, while HVJ-W grew equally well at both temperatures. When BHK cells infected with HVJ-PB were incubated at 38 C, production of infectious virus, hemagglutinin, and neuraminidase was markedly restrained, whereas a considerable amount of viral nucleocapisid and envelope antigens was detected in the cells by complement fixation tests. These viral activities became detectable immediately after temperature shift-down from 38 to 32 C even at the later stage of infection. HVJ-pB was indistinguishable from HJV-W with respect to particle size, density, and morphological characteristics, but appeared to possess a higher neuraminidase activity and was inactivated more rapidly at 50 C than HVJ-W. HVJ-pB was less cytocidal and could easily cause latent infection in BHK and mouse L cells.
Cycloheximide induction of xenotropic type C virus from synchronized mouse cells: metabolic requirements for virus activation
Authors: Greenberger J S , Aaronson S A
Published: January 2020

The information for type C RNA viruses is genetically transmitted within the cellular DNA of the normal mouse cell. These viruses can be induced after exposure of cells to two classes of chemicals, inhibitors of protein synthesis and halogenated pyrimidines. The metabolic requirements for activation of one endogenous virus of BALB/c mouse cells by representatives of each class of drugs were studies. Cycloheximide and iododeoxyuridine each induce virus efficiently from cultures in exponential growth but are inactive on cells in stationary phase. However, cells are maximally sensitive to the actions of each drug at different times within the cell cycle. Further, virus induction in response to each is differentially inhibited under conditions of simultaneous cell exposure to inhibitors of DNA or RNA synthesis. The results provide support for the concept that inhibitors of protein synthesis and halogenated pyrimidines act by different mechanisms to induce type C virus release.
Interaction of Sindbis virus with liposomal model membranes
Authors: Mooney J J , Dalrymple J M , Alving C R , Russell P K
Published: January 2020

Radiolabeled Sindbis virus was found to bind to protein-free lipid model membranes (liposomes) derived from extracts of sheep erythrocytes. The virus interaction was dependent on initial pH, and the range of pH dependence (pH 6.0 to 6.8) was the same as the observed with virus-dependent hemagglutination. After the initial interaction, pH changes no longer influenced the virus binding to liposomes. Virus bound to liposomes prepared from a mixture of erythrocyte phospholipids, but the binding was greatly diminished when either cholesterol or phosphatidylethanolamine was omitted from the liposomal lipid mixture. It was concluded that phospholipids and cholesterol, in a bilayer configuration, may be sufficient for specific virus binding in the absence of membrane protein.
The 3'-terminal nucleotide sequences of adenovirus types 2 and 5 DNA
Authors: Steenbergh P H , Sussenbach J S , Roberts R J , Jansz H S
Published: January 2020

Short nucleotide sequences at the 3'-termini of adenovirus types 2 and 5 DNA have been determined using T4 DNA polymerase as described by P. T. Englund (1972). The terminal sequences of both serotypes appear to be completely identical. Both molecular ends of type 2 as well as of type 5 DNA terminate with the sequence ...pCpC...pGpApTpG3', consistent with the presence of an inverted terminal repetition in adenovirus DNA.
Physiological characterization of temperature-sensitive mutants of mengovirus
Authors: Bond C W , Swim H E
Published: January 2020

Twenty-four temperature-sensitive mutants of mengovirus were characterized physiologically with respect to phenotype. The mutants were separated into four classes on the basis of viral RNA synthesis. L-67-S cells infected with five of the mutants synthesized little viral RNA at 39.5 C. These mutants are designated RNA-. One mutant is designated RNA* since its RNA synthesis is altered at both 39.5 and 31.5 C. The other mutants were divided into two groups, RNA plus or minus (25 TO 49% of wild-type RNA synthesis) and RNA plus (50 to 100% of wild-type RNA synthesis). The time of expression of the mutation in the RNA- mutants was estimated from the results of reciprocal temperature-shift experiments. The mutatation in ts12 appears to be expressed at the time RNA synthesis normally begins. The defect in three of the mutants was expressed 1 to 2 h before RNA synthesis is normally detectable. Protein synthesis is required before RNA synthesis begins when the cells are shifted from 39.5 to 31.5 C. The RNA polymerase synthesized by cells infected with these RNA- mutants at 31.5 C was stable and fully active when assayed at 39.5 C in vitro. The sedimentation profiles of the viral RNA synthesized by cells infected with RNA plus and RNA plus or minus mutants are similar to wild-type profiles with the exception of ts148. Cells infected with this RNA plus or minus mutant synthesize RNA that sediments in a sucrose gradient like replicative-intermediate RNA, but little mature viral RNA is evident. The results of step-up experiments indicate that the temperature-sensitive period for the majority of the RNA plus and RNA plus and minus mutants extends through most of the replicative cycle. The temperature-sensitive defect of four of the mutants, however, was expressed in the first hour, suggesting that some undefined early function is required for the eventual maturation of mengovirus. The virions of three of the RNA- mutants were more thermolabile than wild-type virions. Five of the RNA plus and RNA plus or minus mutants were also thermolabile. Genetic complementation at a significant level was not detectable in mixed infections of the mutants described.
Scanning electron microscopic studies of virus-infected cells. I. Cytopathic effects and maturation of vesicular stomatitis virus in L2 cells
Authors: Holmes K V
Published: January 2020

L2 cells infected with vesicular stomatitis virus under single-cycle conditions have been studied by scanning electron microscopy after preparation by the critical point drying technique. Three dimensional images of intact cells show bullet-shaped vesicular stomatitis virus virions budding singly and in radiating clusters both from the plasma membrane between cellular microvilli and from the sides of microvilli. Virus-induced cytopathic effects observed by scanning electron microscopy include intermeshing of microvilli, loss of filipodia which attach cells to the substrate, and rounding up and detachment of infected cells from the substrate.
Polyoma virus T antigen. I. Synthesis of modified heat-labile T angiten in cells transformed with the ts-a mutant
Authors: Paulin D , Cuzin F
Published: January 2020

In mouse cells transformed with the ts-a mutant of polyoma virus (ts-a-3T3), only low amounts of the virus-specific T antigen were synthesized at high temperature (39 C). After a shift-down to the permissive temperature (31 C), these cells exhibited the same level of T-antigen production as wild-type polyoma transformants. The T antigen produced by ts-a-transformed cells was inactivated at 39 C in vitro at a faster rate than that produced by wild-type-transformed cells. These observations indicate that T antigen is, or includes, a virus-coded peptide.
Characterization of DNA polymerase and RNA associated with A-type particles from murine myeloma cells
Authors: Robertson D L , Baenziger N L , Dobbertin D C , Thach R E
Published: January 2020

The RNA-dependent DNA polymerase present in intracisternal A-type particles from mouse myeloma tumor cells has been studied. This polymerase can use either endogenous A particle RNA or an exogenous synthetic polynucleotide [poly (rA)] as a template. The DNA reaction product is small (4S-10S) and over 90% of it hybridizes to A particle RNA, whereas up to 50% of it hybridizes to murine sarcoma-leukemia virus RNAs. The RNA isolated from purified A particles is generally of low molecular weight (5S-15S) but contains small amount of 70S and 35S components. These results suggest that A-type particles may be related to C-type oncornaviruses.
Alterations in Sindbis Viral Envelope Proteins by Treating BHK cells with Glucosamine
Authors: Duda Ernö , Schlesinger Milton J.
Published: January 2020

Addition of
d
-glucosamine to BHK cells infected with Sindbis virus inhibited the formation of the E-2 viral envelope from its precursor PE-2. Release of virus was blocked, and two new viral protein bands replaced the normal envelope protein bands detected in SDS-gel electropherograms of infected cell extracts.
RNA subunit structure of Mason-Pfizer monkey virus
Authors: Schochetman G , Schlom J
Published: January 2020

Mason-Pfizer monkey virus 60-70S RNA has a molecular weight of 8 times 10-6 when analyzed on polyacrylamide gels. Dissociation of 60-70S RNA of Mason-Pfizer monkey virus and murine leukemia virus by heat or formamide (40%) resulted in conversion to identical subunit structures of 2.8 times 10-6 daltons; treatment with lower amounts of formamide revealed a partial dissociation of Mason-Pfizer monkey virus 60-70S RNA released three low-molecular-weight RNA species of 10-5, 3,5 times 10-4, and 2.5 times 10-4.
Posttranscriptional Selection of Simian Virus 40-Specific RNA
Authors: Khoury George , Howley Peter , Nathans Daniel , Martin Malcolm
Published: January 2020

Analysis of the viral-specific RNA in simian virus 40(SV40)-infected monkey kidney cells indicated the extensive transcription of both DNA strands. These symmetrically transcribed sequences were localized in the nucleus of infected cells, whereas only the “true” early and late SV40 transcripts were found in the cytoplasm. These results suggest that selective posttranscriptional degradation and/or transport occurs after transcription of the viral DNA. On the basis of hybridization experiments with cytoplasmic RNA and the separated strands of the SV40
Hin
fragments, the early SV40 region appears to include all of
Hin
fragments A, H, I, and B (48% of the genome), whereas the late region is represented in
Hin
fragments C, D, E, K, F, J, and G (52% of the genome).
Quantitative assay for transformation of 3T3 cells by herpes simplex virus type 2
Authors: Duff R , Rapp F
Published: January 2020

The interaction of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) with Swiss/3T3 cells was investigated. Virus-induced cytopathic effects developed in the absence of production of infectious virus. HSV-2 inactivated with UV light (2, 4, 6, and 8 min) also induced cell death in the absence of virus replication. Cell death was not detectable after infection by HSV-2 that had been inactivated by UV irradiation for 10, 12, and 14 min. 3T3 cells infected with UV-inactivated virus (10 and 12 min) continued to replicate past the contact-inhibited monolayer normally associated with these cells. Infection of 3T3 cells with UV-irradiated USV-2 also induced the development of transformed foci. Transformed cells with an epithelioid of fibroblastoid morphology were identified and isolated. All HSV-2-transformed cell lines contained HSV-2-specific antigens detectable by immunofluorescence techniques. The maximum frequency of HSV-2-induced transformation was 3 times 105 PFU per transformed focus, and the observed transformation could be inhibited by pretreatment of the virus with specific antiserum. No type C particles were detected within five cell culture passages after transformation by HSV-2. Type C virus particles were detected after 10 cell culture passages of the HSV-2-transformed cell lines.
Phosphoproteins: structural components of oncornaviruses
Authors: Pal B K , Roy-Burman P
Published: January 2020

Oncornaviruses, which contain a virion-associated protein kinase, were found to possess phosphoproteins as virion structural components. One major phosphoprotein common to strains of laboratory and wild mouse oncornaviruses and a strain of feline leukemia virus was shown to be a polypeptide of about 12, 000 mol wt. In addition to this, the Kirsten strain of murine sarcoma virus contained a second major phosphoprotein of about 10, 000 mol wt, and mouse erythroblastosis virus contained a second major phosphoprotein that was either identical to or comigrated with the virion glycoprotein of about 74, 000 mol wt. The major phosphoprotein of RD-114 virus was found to be of about 16, 000 mol wt. The major phosphoamino acid of the 12, 000-mol wt polypeptide of the mouse erythroblastosis virus was identified as phosphoserine, and that of the 16, 000-mol wt polypeptide of the RD-114 virus was identified as phosphothreonine.
Translation and identification of the viral mRNA species isolated from subcellular fractions of vesicular stomatitis virus-infected cells
Authors: Both G W , Moyer S A , Banerjee A K
Published: January 2020

The cytoplasm of vesicular stomatitis virus (VSV)-infected BHK cells has been separated into a fraction containing the membrane-bound polysomes and the remaining supernatant fraction. Total poly(A)-containing RNA was isolated from each fraction and purified. A 17S class of VSV mRNA was found associated almost exclusively with the membrane-bound polysomes, whereas 14,5S and 12S RNAs were found mostly in the postmembrane cytoplasmic supernatant. Poly(A)-containing VSV RNA synthesized in vitro by purified virus was resolved into the same size classes. The individual RNA fractions isolated from VSV-infected cells or synthesized in vitro were translated in cell-free extracts of wheat germ, and their polypeptide products were compared by sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis. The corresponding in vivo and in vitro RNA fractions qualitatively direct the synthesis of the same viral polypeptides and therefore appear to contain the same mRNA species. By tryptic peptide analysis of their translation products, the in vivo VSV mRNA species have been identified. The 17S RNA, which is compartmentalized on membrane-bound polysomes, codes for a protein of molecular weight 63,000 (P-63) which is most probably a nonglycosylated form of the viral glycoprotein, G. Of the viral RNA species present in the remaining cytoplasmic supernatant, the 14.5S RNA codes almost exclusively for the N protein, whereas the 12S RNA codes predominantly for both the NS and M proteins of the virion.
Mosquito cells infected with vesicular stomatitis virus yield unsialylated virions of low infectivity
Authors: Schloemer R H , Wagner R R
Published: January 2020

Vesicular stomatitis virus propagated in and released from Aedes albopictus cells had the normal complement of viral proteins; the glycoprotein contained carbohydrate but no sialic acid. These virions had markedly reduced hemagglutinating activity and exhibited a very high ratio of physical particles to infectious virus. In vitro sialylation of vesicular stomatitis virions grown in mosquito cells resulted in a 100-fold increase in both infectivity and hemagglutination titers to levels approaching those of virus grown in BHK-21 cells. These experiments provide an example of host-controlled modification of viral infectivity.
Influenza virion RNA-dependent RNA polymerase: stimulation by guanosine and related compounds
Authors: McGeoch D , Kitron N
Published: January 2020

The activity of RNA-dependent RNA polymerase of several influenza viruses is stimulated by guanosine. Depending upon the virus strain used, the stimulation of initial reaction rate is up to 10-fold. 5'-GMP, 3',5'-cyclic GMP, and 5'-GDP show lesser stimulation effects. No other nucleosides of 5'-NMPs stimulate, but the dinucleoside monophosphates GpG and GpC show large stimulations. We present evidence that the stimulation represents preferential initiation of genome complementary RNA chains with guanosine: (i) [3-H] guanosine is incorporated specifically at the 5'terminus of RNA in polymerase reaction mixes in vitro. (ii) This incorporation reaction has several properties similar to those of the virion polymerase elongation reaction. (iii) RNA made in the stimulated reaction behaves as complementary RNA in annealing kinetic studies, as does RNA labeled with [3-H]guanosine.
Complementation of defective reovirus by ts mutants
Authors: Spandidos D A , Graham A F
Published: January 2020

Defective reovirions lacking the largest (L-1) of the normal 10 genomic segments grow only in association with helper reovirus. Because of the similarity in properties of defective and infectious virions, separation of the two populations by physical methods has been unseccessful. Controlled digestion of purified virus removes the outer capsomeres of the virions. The resulting core particles containing the viral genome have a buoyant density of 1.43/ml if derived from infectious virions and of 1.415g/ml if they originate in defectives, and this difference permits ready separation of the two types of cores. With the purpose of obtaining a pure population of defective virions, L cells were co-infected with defective cores and a class E temperature-sensitive mutant which has a mutation in an early function. After three serial passages at the permissive temperature (31 C) to build up the defective population, a fourth passage was made at 39 C, the nonpermissive temperature. The virus purified from this passage was predominantly defective; it contained practically no E mutant and had a low background of wild-type virus. Complementation was thus asymmetric; the L-1 function required for growth of defective virus was supplied by the E mutant and is thus a trans-function, while defective virus did not complement the E mutation which is thus in a cis-acting function. Defective virions were indistinguishable from infectious virions except for the absence of the L-1 genomic segment in the defectives. Such defective virions could be complemented at 39 C by class A and B temperature-sensitive mutants, both of which have lesions in late functions.
Escherichia coli capsule bacteriophages. IV. Free capsule depolymerase 29
Authors: Bessler W , Fehmel F , Freund-Mölbert E , Knüfermann H , Stirm S
Published: January 2020

The free host capsule depolymerase, induced by Escherichia coli capsule bacteriophage no. 29, and causing the formation of haloes around its plaques, has been purified to homogeneity. As judged from the following facts, this "enzyme" consists of free phage 29 spikes. (i) Detached phage organelles and depolymerase 29 particles exhibit the same molecular weight (about 245,000, as determined from the sedimentation equilibrium), contain polypeptide chains of the same two sizes (57,000 plus or minus 3,000 and 29,500 plus or minus 2,000, as determined by SDS-PAA gel electrophoresis), and have (within experimental error) the same sedimentation coefficient, isoelectric point, and amino acid composition. (ii) Isolated depolymerase and phage spikes in situ both catalyze the hydrolysis of glucosidic bonds in host capsular polysaccharide, leading ultimately to the formation of oligosaccharide fragments of one, two, and three hexasaccharide repeating units. (iii) Depolymerase 29 and phage 29 spikes have roughly the same electron optical dimensions. As tentatively estimated from the total and the virus-associated capsule depolymerase activity in the lysates, phage 29 infection seems to produce eight to seventeen times more free than incorporated spikes.