bluuebunny/crossref_metadata_2025 huggingface dataset:
Conditional Temperature-sensitive Restriction of
Pseudomonas
Bacteriophage CB3
Authors: Olsen R. H. , Metcalf Eleanor S. , Brandt Carl
Published: January 2020

Restriction of
Pseudomonas
bacteriophage CB3 growth on some
Pseudomonas aeruginosa
hosts was studied. On restricting hosts, growth of this phage was severely inhibited below 32 C and hence was temperature-sensitive. Investigation of this phenomenon revealed that restricting hosts were not killed as a consequence of their infection under nonpermissive conditions. The ability of some hosts to restrict showed segregation in sexual crosses between restricting and nonrestricting hosts. However, the pattern of restriction among various hosts differed with the phage in question when other phages were compared with CB3. Temperature-shift experiments indicated that blockage of an early event in the phage lytic cycle occurred when restricting conditions were imposed on cells infected with CB3. This blockage could be eliminated by holding at permissive conditions until the cold-sensitive step was bypassed or by pulsing restricting cells for 5 min at 37 C.
Physicochemical and Biological Properties of Fibrous
Pseudomonas
Bacteriophages
Authors: Minamishima Y. , Takeya K. , Ohnishi Y. , Amako K.
Published: January 2020

Two fibrous
Pseudomonas
phages, Pf1 and Pf2, have been isolated and characterized. The phages were serologically related and were indistinguishable morphologically when viewed by electron microscopy. Both phages formed minute turbid plaques. A simple method was devised for easy differentiation of such plaques from the bacterial lawn. The infected bacteria continued to grow and to liberate the phages into the medium. The phages were collected from the turbid “lysate” by salting out and were purified by differential centrifugation and density gradient centrifugation. The purified phages were sensitive to ultrasonics and to a proteolytic enzyme, Nagarse. A rapid lysis mutant was obtained from the progeny of plaquepurified Pf2. Pf2 was spontaneously produced by strain P28 of
P. aeruginosa.
Neither acridine orange nor antiserum affected the phage-producing capacity of the bacteria.
Number of Virus Particles in Insects and Plants Infected with Wound Tumor Virus
Authors: Streissle Gert , Bystricky Vojtech , Granados Robert R. , Strohmaier Karl
Published: January 2020

A new procedure for counting virus particles was employed to measure the concentration of wound tumor virus in purified virus preparations, in plant tumors, and in the insect vector. Partially purified wound tumor virus was used to establish the quantitative features of the method. A 1-g amount of plant tumor tissue contained an average of 5 × 10
10
virus particles and 1 g of insect tissue contained 2 × 10
10
particles.
A Mathematical Analysis of Concomitant Virus Replication and Heat Inactivation
Authors: Purifoy D. J. M. , Purifoy J. A. , Sagik B. P.
Published: January 2020

A mathematical analysis of virus production with accompanying heat inactivation, from which the rate of virus release and total virus production are readily calculated, is presented. Applications of this analysis for Sindbis and Chikungunya viruses are discussed.
Characteristics of Bacteriophages Attacking Psychrophilic and Mesophilic Pseudomonads
Authors: Olsen R. H. , Metcalf Eleanor S. , Todd James K.
Published: January 2020

Ten
Pseudomonas
phage were isolated by sewage enrichment. Five psychrophilic and five mesophilic phage were selected for a description of some of their biological properties. In addition to growth on psychrophilic hosts, the psychrophilic phage studied were also able to grow on a mesophilic host within its growth temperature range. Latent periods for psychrophilic phage at 3.5 C were 6 to 12 hr and at 25 C were 30 to 60 min. Mesophilic phage had a latent period of 85 to 190 min at 25 C and 35 to 85 min at 37 C. Psychrophilic phage were significantly more heat-sensitive than the mesophilic phage. Of all the parameters studied, only thermal sensitivity correlated with growth at 3.5 C. Phage used in this study had a deoxyribonucleic acid base composition ranging from 39.6 to 68.2% guanine plus cytosine, deduced from melting temperature measurements.
Ultrastructure of Lymphocystis Virus
Authors: Zwillenberg Lutz O. , Wolf Ken
Published: January 2020

Lymphocystis virus obtained from bluegills (
Lepomis macrochirus
) was cultured in the permanent bluegill cell line BF-2 and examined by electron microscopy in ultrathin sections of cell cultures and in negative-contrast preparations from cells and from centrifuged culture medium. According to negative-contrast preparations, the icosahedral virions have an overall diameter close to but not exceeding 300 mμ. Delicate filaments seem to issue from the vertices. In collapsed virions, an ordered array of morphological units was seen. Positively contrasted virions in ultrathin sections show a shell with three dark (heavy metal-stained) layers alternating with and separated by two clear layers. The acquisition of an additional outer membrane during release from the cell, as found in African swine fever virus, was never seen. Morphologically, lymphocystis virus is considered to be closely related to Tipula iridescent virus.
Biosynthesis of Host and Viral Deoxyribonucleic Acid During Hyperplastic Fowlpox Infection In Vivo
Authors: Cheevers William P. , O'Callaghan Dennis J. , Randall Charles C.
Published: January 2020

The synthesis of deoxyribonucleic acid (DNA) during in vivo infection of chick epithelium with fowlpox virus was examined by incorporation of tritiated thymidine into the acid-insoluble fraction. The proportion of precursor incorporated into host and viral DNA at various times after infection was determined by chromatography on columns of methylated albumin-kieselguhr. The first 60-hr period of infection was characterized by the synthesis of predominantly host DNA, the rate of production of which increased markedly over the control between 36 and 48 hr postinoculation (PI). Although the replication of viral DNA began between 12 and 24 hr PI, the rate of synthesis was very low during the first 60 hr. In contrast, an abrupt increase in the rate of viral DNA synthesis occurred between 60 and 72 hr PI, concomitantly with a sharp decline of host DNA synthesis. Subsequently, between 72 and 96 hr, the ratio of synthesis of viral DNA to host DNA progressively increased to a maximum of greater than 2:1. The temporal relationship of this biphasic pattern of host and viral DNA synthesis to hyperplasia and viral replication is discussed.
Mengovirus Replication in Novikoff Rat Hepatoma and Mouse L Cells: Effects on Synthesis of Host-Cell Macromolecules and Virus-specific Synthesis of Ribonucleic Acid
Authors: Plagemann Peter G. W.
Published: January 2020

Novikoff cells (strain N1S1-67) and L-67 cells, a nutritional mutant of the common strain of mouse L cells which grows in the same medium as N1S1-67 cells, were infected with mengovirus under identical experimental conditions. The synthesis of host-cell ribonucleic acid (RNA) by either type of cell was not affected quantitatively or qualitatively until about 2 hr after infection, when viral RNA synthesis rapidly displaced the synthesis of cellular RNA. The rate of synthesis of protein by both types of cells continued at the same rate as in uninfected cells until about 3 hr after infection, and a disintegration of polyribosomes occurred only towards the end of the replicative cycle, between 5 and 6 hr. The time courses and extent of synthesis of single-stranded and double-stranded viral RNA and of the production of virus were very similar in both types of cells, in spite of the fact that the normal rate of RNA synthesis and the growth rate of uninfected N1S1-67 cells are about three times greater than those of L-67 cells. In both cells, the commencement of viral RNA synthesis coincided with the induction of viral RNA polymerase, as measured in cell-free extracts. Viral RNA polymerase activity disappeared from infected L-67 cells during the period of production of mature virus, but there was a secondary increase in activity in both types of cells coincidental with virus-induced disintegration of the host cells. Infected L-67 cells, however, disintegrated and released progeny virus much more slowly than N1S1-67 cells. The two strains of cells also differed in that replication of the same strain of mengovirus was markedly inhibited by treating N1S1-67 cells with actinomycin D prior to infection; the same treatment did not affect replication in L-67 cells.
Chemically Induced Cofactor Requirement for Bacteriophage T4D
Authors: Gamow R. I. , Kozloff L. M.
Published: January 2020

The treatment of bacteriophage T4D with 2-hydroxy-5-nitrobenzyl bromide, a specific reagent for alkylating the indole ring of tryptophan residues, converts these particles from a cofactor-independent form to a cofactor-sensitive form. These treated T4D particles phenotypically resemble T4B particles in certain respects. Their ability to form plaques on minimal medium plates is increased by the addition of
l
-tryptophan and is inhibited by the addition of indole. In liquid medium, their rate of adsorption is dependent on the presence of the cofactor
l
-tryptophan.
l
-Tryptophan-requiring phage have been produced by in vitro assembly of treated tail-fiberless particles of a T4D amber mutant plus untreated tail fiber preparation. When treated tail fibers were used with untreated tail-fiberless particles, the newly assembled particles did not require cofactor. A model of the tail structure of all the T-even bacteriophages is presented which postulates that the active configuration of the tail fibers requires that there be either (i) an endogenous tryptophan residue of the phage particle itself or (ii) an exogenously added
l
-tryptophan molecule complexed with a specific tryptophan receptor site, most likely on the phage base plate.
Replicative Intermediate of an Arbovirus
Authors: Friedman Robert M.
Published: January 2020

One hour after infection of chick fibroblasts with Semliki Forest virus (SFV), a viral ribonucleic acid (RNA) structure is present which has many of the properties described for the replicative intermediate of several RNA bacteriophages. These properties include a polydisperse nature on sucrose density gradient analysis, ribonuclease resistance, a variation in sedimentation pattern associated with changes in salt concentration, and recovery of infectious viral RNA upon denaturation. Most of the replicative intermediate present in SFV infection appears to be membrane-associated.
Replication of Western Equine Encephalomyelitis Virus
Authors: Sreevalsan T. , Lockart R. Z. , Dodson M. L. , Hartman K. A.
Published: January 2020

The ribonucleic acid (RNA) from Western equine encephalomyelitis (WEE) virions sedimented through sucrose gradients with a sedimentation coefficient of 40
S
. Another viral RNA which was always associated with infected cells possessed a sedimentation coefficient of 26
S
. Both 40
S
and 26
S
RNA had identical base compositions and densities. The 40
S
RNA displayed a hyperchromic effect when heated with a T
m
of 57.5 C. When 40
S
RNA was heated at 90 C and cooled rapidly, it sedimented with a coefficient of 26
S
. Dialysis of 40
S
RNA against distilled water changed its sedimentation coefficient to 26
S
. The presence of 8
m
urea or 50% dimethyl sulfoxide in the gradients also altered the sedimentation rate of 40
S
RNA to 26
S
. In the latter case, the 26
S
RNA retained 10% of the infectivity originally added as 40
S
RNA. Dialysis of 26
S
RNA against 0.5
m
NaCl or 0.05
m
acetate buffer at
p
H 4.0 altered it so that about 50% of the radioactivity sedimented with a coefficient of 40
S
. Chromatography on methylated albumin-kieselguhr columns failed to separate 40
S
RNA from 26
S
RNA. Viral RNA either exists in two conformations which sediment differently in sucrose or contains an extremely labile portion near the center and is easily broken into two equal pieces.
Transducing Bacteriophage for
Bacillus cereus
Authors: Thorne Curtis B.
Published: January 2020

A phage, designated CP-51, that carries out generalized transduction in
Bacillus cereus
569 was isolated from soil. All auxotrophic mutants tested, those requiring tryptophan, histidine, leucine, isoleucine, methionine, or phenylalanine, were transduced to prototrophy. The phage was extremely unstable when stored at 2 to 4 C, but stability was enhanced by storage at higher temperatures. The optimal temperature of those tested for maintenance of plaque-forming units was 15 C.
Maturation Defects in Temperature-sensitive Mutants of Sindbis Virus
Authors: Yin Fay H. , Lockart R. Z.
Published: January 2020

Temperature-sensitive mutants of Sindbis virus, which synthesize viral ribonucleic acid (RNA) but not mature virus at the nonpermissible temperature, were selected for the study of viral maturation. Of these, three mutants which complement each other genetically were used. Two major proteins, the nucleocapsid and membrane proteins, located, respectively, in the viral nucleoid and membrane, were found in intact virions. In cells infected with wild-type Sindbis virus, four distinct types of viral RNA with sedimentation coefficients of 40
S
, 26
S
, 20
S
, and 15
S
were detected in constant distribution. The 20
S
RNA was ribonuclease-resistant, whereas the other types were ribonuclease-sensitive. The 40
S
RNA, identical to that obtained from the virion, was found associated with nucleocapsid protein as a subviral particle, which was assumed to be the nucleoid. Viral materials from cells infected with the mutants under nonpermissive conditions were compared with those from cells infected with wild-type virus, in terms of (i) the distribution of the different types of RNA, (ii) the association of infectious viral RNA into subviral particles, and (iii) the ability of infected cells to hemadsorb goose erythrocytes. According to these criteria, each of the three mutants demonstrated different maturation defects. Defective nucleocapsid proteins and membrane proteins may each account for one of the above mutants. The thrid mutant may have defects in a minor structural protein or possibly a maturation protein which is involved in the assembly of Sindbis virus.
Chromosomal Aberrations and Cloning Efficiency in Adenovirus Type 12-infected Hamster Cells
Authors: zur Hausen Harald
Published: January 2020

The fate of hamster cells, abortively infected with adenovirus type 12, has been studied by correlation of chromosomal aberrations with induction of T antigens and cloning efficiency. The incidence of chromosomal changes paralleled to some extent the T antigen formation, but was inversely related to the cloning efficiency of the cells. At an input multiplicity of 100, within 24 hr after infection, nearly all of the cells or metaphases revealed the presence of T antigens and chromosomal lesions, respectively, but no clones of cells were obtained. Inhibition of cellular deoxyribonucleic acid synthesis was not noted during this period. Increasing doses of ultraviolet irradiation reduced, successively, the capacity of the virus to induce chromosomal aberrations and correspondingly improved cloning efficiency of the exposed cells. It is concluded that most, if not all, cells revealing chromosomal lesions 24 hr after infection fail to enter further mitoses.
Persistence of the Viral Genome in Adenovirus Type 12-infected Hamster Cells
Authors: zur Hausen Harald
Published: January 2020

Induction of T antigen by adenovirus type 12 was studied in growing and growth-inhibited cultures of the Nil-2 line of Syrian hamster cells. At a viral input multiplicity of 10, neoantigen was present in 100% of the cells by 24 hr. T antigen gradually disappeared in descendants of these cells so that 2 weeks after infection only 1% gave specific immunofluorescence. When cellular replication was prevented by addition of fluorodeoxyuridine, T antigen persisted in all cells for the 2-week period. Upon infection of growing cultures with purified
3
H-labeled adenovirus type 12 and autoradiographic analysis of the cells at various times thereafter, a gradual reduction in labeled nuclear loci was noted which paralleled the decrease in T antigen-containing cells. In nongrowing cultures, no change in labeled loci was noted. Correlation of T antigen and labeled loci revealed that fluorescent cells contained, on the average, about 10 times more silver grains than nonfluorescent cells. All of 92 preselected fluorescent cells showed labeled loci, whereas, of 100 nonfluorescent cells, 18 were free of silver grains. The implications of these findings are discussed.
Characterization of polysome-associated RNA from influenza virus-infected cells
Authors: Nayak D P , D'Andrea E , Wettstein F O
Published: January 2020

Virus-specific polysome-associated RNA (psRNA) and RNA after dissociation of polysomes were analyzed by direct hybridization with unlabeled viral RNA (vRNA) and complementary RNA (cRNA). psRNA after a 30-min pulse with [3H]uridine contained 28% labeled cRNA, 70% host RNA, and no vRNA. After dissociation, psRNA sedimented heterogeneously. Heavy RNA (greater than 60S), ribosomal subunit RNA (rsuRNA, 30-60S), free mRNA (fmRNA, 10-30S), and light RNA (less than 10S) contained 16%, 54%, 70% and 28% cRNA, respectively, but no vRNA. When actinomycin D (AcD) was added at 2 h postinfection, the nature of the psRNA depended on the concentration of AcD and the condition of the labeling. At AcD concentrations of 1 mug or more per ml, no detectable vRNA or cRNA was associated with polysomes. At 0.2 mug of AcD per ml (a concentration that partially inhibited cRNA synthesis) and 2 h of labeling at 2.5 h postinfection, psRNA contained 40% viral-specific RNA, which included both vRNA and cRNA in almost equal amounts. When polysomes were dissociated, however, viral-specific fm RNA from AcD-treated cells contained exclusively cRNA and no detectable vRNA. Increasing amounts of labeled vRNA were present in the heavy region of the gradient (and in the pellet), which also contained varying amounts of cRNA. The labeled vRNA appears to be associated with polysomes in a cesium chloride density gradient (rho = 1.525 g/ml). Although we have ruled out the trivial explanation of viral ribonucleoprotein contamination,the nature of the complex containing both polysomes and vRNA is unknown.
Polyoma genome in hamster BHK-21-C13 cells: integration into cellular DNA and induction of the viral replication
Authors: Folk W R , Bancuk J E
Published: January 2020

When grown at 39.5 degrees C, BHK-21 C-13 cells transformed by A gene mutants of polyoma virus contain viral sequences that are predominantly associated with cellular DNA pelleted in the Hirt lysis procedure. At this temperature, in cells that are inducible for viral DNA replication (Folk, 1973), the majority of the viral genomes are covalently joined with cellular DNA's containing repetitious sequences. Upon a shift to 31 degrees C, free viral genomes appear and are replicated. Coupled with the replication of the free viral genomes at 31 degrees C is an increase in the viral genomes associated with cellular DNA.
Genetic studies of coliphage P1. III. Extended genetic map
Authors: Walker D H , Walker J T
Published: January 2020

An extensive genetic map of coliphage P1 has been constructed for 113 amber mutants, using primarily a modification of the conventional complementation spot test. These spot tests failed to classify the mutants into cistrons, but when they were quantitated they permitted assignment of the mutants into 10 linkage clusters. Furthermore, a linear order could be deduced for most of the mutants within each cluster. This strongly suggested that recombination was the predominant event generating plaques and that, for the practical purpose of rapid genetic mapping, such spot tests could be considered as a series of two-factor crosses. Six of the 10 linkage clusters correlated with the P1 genetic map established by Scott (1968). The locations of the remaining four clusters were determined by three-factor crosses and by prophage deletion mapping. The nonrandom occurrence of termini for 14 deletion prophages, which we established previously (Walker and Walker, 1975), and the coincidence of these termini with five out of ten regions demarcating the linkage clusters are discussed. Complementation tests in liquid frequently gave ambiguous results. Therefore, cistron designations were not assigned.
Semliki Forest virus capsid protein associates with the 60S ribosomal subunit in infected cells
Authors: Ulmanen I , Söderlund H , Kääriäinen L
Published: January 2020

Semlike forest virus capsid protein cosedimented with the large ribosomal subunit at 60S in sucrose gradients after treatment of cytoplasm from infected cells with Triton X-100 and EDTA. In CsCl gradients the capsid protein banded with the subunit at a density of 1.56 to 1.57 g/cm3. Most of the capsid protein could be detached from the 60S structure by treatment with 0.8 M KCl. The ribonucleoprotein of the 26S RNA had a sedimentation value of 53S and a density of 1.50 g/cm3 and could thus be separated from the 60S structure. The data suggest that the capsid protein binds to the large ribosomal subunit, but not to the viral 26S RNA.
Selection and identification of influenza virus recombinants of defined genetic composition
Authors: Schulman J L , Palese P
Published: January 2020

The RNAs of influenza virus recombinants were analyzed on polyacrylamide gels under conditions in which the derivation of specific RNA segments (including those coding for hemagglutinin and neuraminidase) could be determined. Analysis of the RNAs of recombinant viruses with identical hemagglutinin and neuramindase revealed that the derivation of the remaining genes could be influenced by UV irradiation of one of the parent viruses. In five of seven such recombinants all of the remaining identifiable genes were derived from the nonirradiated parent, whereas in two others only the three largest RNA segments were derived from the nonirradiated parent. Analysis of the RNA pattern of a recombinant isolated from mixed infection in which neither parent was irradiated demonstrated a random mixture of RNA segments derived from the two parent viruses.
DNA of minute virus of mice: self-priming, nonpermuted, single-stranded genome with a 5'-terminal hairpin duplex
Authors: Bourguignon G J , Tattersall P J , Ward D C
Published: January 2020

The genome of the nondefective parvovirus minute virus of mice (MVM) is a linear DNA molecular weight 1.48 x 10(6), which is single stranded for approximately 94% of its length. In contrast to the genomes from defective parvoviruses MVM DNA does not contain a detectable inverted terminal redundancy. A combination of enzymatic and physical techniques has shown that the molecule contains a stable hairpin duplex of approximately 130 base pairs located at the 5' terminus of the genome. MVM DNA is efficiently utilized as a template-primer by a number of DNA polymerases, including reverse transcriptases. Polymerases lacking 5' to 3' exonuclease activity yield a duplex DNA product with a molecular weight 1.96 times that of the viral genome, in which the newly synthesized complementary strand is covalently attached to the template. This duplex contains an internal "nick" that can be sealed by DNA ligase to produce a self-complementary single-strand circle. The MVM DNA duplex is cleaved twice by EcoR-RI restriction endonuclease to yield three distinct fragments in molar amounts. These results suggest that the initiation of DNA synthesis in vitro occurs at a point within 100 bases of the 3' end of the genome, using the 3' terminus of viral DNA as a primer, and that the sequence of nucleotides in the genome is not permuted.
Physicochemical Characterization of the Male-Specific RNA Bacteriophage μ2: Serological Comparison with R17, fr, and Qβ
Authors: Piffaretti Jean-Claude , Pitton Jean-Samuel
Published: January 2020

The physicochemical values and amino acid composition determined for bacteriophage μ2 suggest a close relationship with R17 and fr; significant differences are found with Qβ; these results are supported by serological studies.
5′-Terminus of Moloney Murine Leukemia Virus 35
S
RNA Is m
7
G
5′
ppp
5′
GmpCp
Authors: Rose John K. , Haseltine William A. , Baltimore David
Published: January 2020

The 5′-terminal sequence m
7
G
5′
ppp
5′
GmpCp was isolated from Moloney murine leukemia virus 35
S
RNA after digestion of
32
P-labeled RNA with RNases T1, T2, and A followed by pH 3.5 ionophoresis on DEAE paper.
RNA complementary to the genome of RNA tumor viruses in virions and virus-producing cells
Authors: Stavnezer E , Ringold G , Varmus H E , Bishop J M
Published: January 2020

Cells producing type C (avain sarcoma virus) or type B (mouse mammary tumor virus) RNA tumor viruses contain small amounts of RNA complementary to the viral genomes. The negative strands are complementary to at least 30 to 45% of the viral genomes and are found as RNA-RNA duplexes in the nucleus and cytoplasm of infected cells and in mature virions.
Recombination and Complementation Between Temperature-Sensitive Mutants of a Bunyavirus, Snowshoe Hare Virus
Authors: Gentsch Jon , Bishop David H. L.
Published: January 2020

Complementation and recombination have been observed with temperature-sensitive mutants of Bunyavirus snowshoe hare virus.
New temperate bacteriophage for Bacillus subtilis, rho 11
Authors: Dean D H , Orrego J C , Hutchison K W , Halvorson H O
Published: January 2020

A new temperate bacteriophage, rho11, isolated by J. Hoch, has been characterized. This new phage is very similar to the temperate phage phi3T in size (380 nm), host range, homoimmunity, DNA buoyant density (1.694 g/ml), antigenicity, and molecular weight (around 6.0 X 10(7)) as determined in gels. Like phi3T, rho11 converts thymine auxotrophs to prototrophy at high frequency (250 out of 250 tested). Phage rho11 differs from phi3T in plaque morphology and in the endonuclease R-EcoRI digest pattern. Sixteen of the 20 rho11 DNA fragments have migration patterns corresponding to those of the 21 fragments of phi3T. The close similarities yet clear differences between these phages suggest that the two phages have a common ancestor.
Structural proteins of polyoma virus: proteolytic degradation of virion proteins by exogenous and by virion-associated proteases
Authors: Friedmann T
Published: January 2020

A model has previously been proposed for the genetic relatedness of the structural proteins of polyoma virus, based upon similarities in the peptide maps of the major capsid protein VP1 with the virion proteins VP2 and VP3. Newer evidence suggests that this model is incorrect, and that protein VP1 is a product of one viral gene and that the multiple components of VP2 and VP3 are products of a second viral gene. Two-dimensional peptide maps of several preparations of polyoma purified separately from four separate infected-cell lysates has shown a variable content of VP1 peptides in proteins VP2 and VP3, with some preparations being free of detectable VP1 material in VP2 and VP3. An alternative explanation for the presence of VP1 peptides in the regions of VP2 and VP3 of some polyoma preparations involves the cleavage of proteins of polyoma virions during exposure to proteolytic enzymes in lysates of infected cells or to endogenous proteolytic activity of virions. Prolonged incubation of infected-cell lysates at 37 degrees C leads to an increase in the amount of 86,000-dalton dimer of VP1, a decrease in the relative amount of VP1, a decrease in or a loss of the lower band of VP2, and the appearance of a new major protein band of approximately 29,000 daltons. Two-dimensional peptide maps of the new 29,000-dalton protein show that it contains some VP1 peptides, indicating that this protein is derived from proteolytic cleavage of VP1. In addition, extensively purified polyoma virus contains a proteolytic activity that can be activated during disruption of the virus with 0.2 M Na2CO3-NaHCO3 (pH 10.6) in the presence of 5 X 10(-3) M dithiothreitol.
Anatomy of herpes simplex virus DNA. VI. Defective DNA originates from the S component
Authors: Frenkeĺ N , Locker H , Batterson W , Hayward G S , Roizman B
Published: January 2020

We previously reported that serial propagation of the Justin strain of herpes simplex virus 1 [HSV-1 (Justin)] results in the generation of defective DNA molecules consisting of tandem repetitions of sequences of limited complexity. In the present study, HSV-1 DNA was cleaved with the restriction endonucleases BglII and EcoRI. The fragments were electrophoretically separated on agarose gels, transferred to nitrocellulose strips, and then hybridized with 32P-labeled HSV-1 (Justin) defective DNA. The data allow us to conclude that DNA sequences contained in the repeat unit of defective DNA originate from the S segment of the wild-type viral DNA molecule.
Bacteriophage PBS2-induced inhibition of uracil-containing DNA degradation
Authors: Katz G E , Price A R , Pomerantz M J
Published: January 2020

Degradation of uracil-containing DNA by Bacillus subtilis extracts and its inhibition after infection by the uracil-containing DNA phage PBS2 have been investigated to resolve differences between the published reports of Tomita and Takahashi (1975) and Friedberg et al. (1975, 1976). The product of hydrolysis of PBS2 DNA, tritium labeled in its uracil and cytosine residues, is solely uracil and not deoxyuridine. The degrading activity is completely inhibited within 7 min after PBS2 infection, before any other known PBS2-induced protein is detectable. The production of the PBS2 inhibitor (a small, heat-stable protein) continues until 10 to 20 min postinfection.
Content and expression of integrated viral DNA in hamster cells transformed by nondefective adenovirus type 2- simian virus 40 hybrid viruses
Authors: Breeden J H , Wewerka-Lutz Y , Schnipper L E , Hauser J , Patch C T , Lewis A M , Levine A S
Published: January 2020

Hamster cells transformed by adenovirus 2 (Ad2) and five nondefective Ad2-simian virus 40 (SV40) hybrid viruses are all of the Ad2-transformed phenotype. All lines accumulate Ad2 RNA and Ad2 T antigen; two hybrid-transformed lines accumulate SV40 RNA, but only one contains detectable amounts of SV40 antigens. We examines selected lines from this group of transformed hamster cells for Ad2 DNA content and viral RNA expression by using hydroxyapatite chromatography and separated strands of labeled viral DNA as probes. All lines studies contain 1 to 2 Ad2 genome equivalents per haploid equivalent of cell DNA. The expression of Ad2 RNA exhibits two distinct patterns. In one pattern, transcription of the heavy strand of Ad2 DNA is less than that of the light strand, whereas in the second pattern of Ad2 RNA expression the extent of heavy-strand transcription is greatly increased. In the two lines containing SV40 RNA, the entire SV40 (-) strand is transcribed; the (+) strand is not expressed in these cells. These patterns of viral RNA expression suggest the possibility that host promoters may play a role in regulating transcription of integrated viral DNA.
Genetic evidence for a product of the Fv-1 locus that transfers resistance to mouse leukemia viruses
Authors: Tennant R W , Schluter B , Myer F E , Otten J A , Yang W K , Brown A
Published: January 2020

Extracts of mouse cells have been shown to transfer to N- or B-trophic host range types of mouse leukemia viruses. The genetic specificity of the inhibition was tested in two ways: (i) by correlating the Fv-1 genotype of a number of mouse strains with the restriction-transferring activity of extracts of the respective embryo cell cultures, and (ii) by correlating the Fv-1 genotype of BLC3F2 (C57BL/6 female [Fv-1bb] by C3H male [Fv-1nn] parental strains) mouse embryos, which segregate the Fv-1 alleles in a 12:1 ratio, with the inhibitor activity of extracts of the cells from each embryo. Five independent matings, totaling 45 individual embryos, were tested. Each embryo was cultured, and the Fv-1 genotype was determined independently by titration of N- and B-tropic viruses; the extracts of replicate secondary cultures were tested for their effect on infection of permissive cells by N- and B-tropic viruses. The specific-restriction-transferring activity of the embryos was found to segregate with the appropriate Fv-1 genotype. These res-lts confirm the suggestion that the inhibitor of the leukemia virus host range types in the cellular extracts is a product of the Fv-1 locus.
Effect of hypertonic medium on protein synthesis of Mahoney and LSc poliovirus
Authors: Tershak D R
Published: January 2020

The initiation of synthesis of Mahoney virus protein is more sensitive to high osmolarity than initiation of synthesis of LSc virus protein. Production of Mahoney virus protein appears to be only slightly more resistant to high osmolarity than synthesis of HeLa-Rhino cell protein.
Segmented genome and nucleocapsid of La Crosse virus
Authors: Obijeski J F , Bishop D H , Palmer E L , Murphy F A
Published: January 2020

La Crosse (LAC) virions purified by velocity and equilibrium gradient centrifugation contained three single-stranded RNA species. The three segments had sedimentation coefficients of 31S, 25S, and 12S by sodium dodecyl sulfate-sucrose gradient centrifugation. By comparison with other viral and cellular RNA species, the LAC viral RNAs had molecular weights of 2.9 x 10(6), 1.8 x 10(6), and 0.4 x 10(6). Phenol-sodium dodecyl sulfate-extracted LAC virion RNA was not infectious for BHK-21 cell cultures under conditions in which Sindbis viral RNA was infectious. Treatment of LAC virus with the nonionic detergent Triton X-100 and salt released three nucleocapsid structures, each containing one species of virion RNA. The nucleocapsids had sedimenation coefficients of 115S, 90S, and 65S. Negative-contrast electron microscopy of the nucleocapsids indicated that they were convoluted, supercoiled, and apparently circular. They had a mean diameter of 10 to 12 nm and modal lengths of 200, 510, and 700 nm (some were even longer). By chemical and enzymatic analysis of purified viral RNA, one type of 5' nucleotide (pppAp) present in the proportion of one per RNA segment was identified. After periodate oxidation, each virion RNA species was labeled by reduction with [3H]sodium borohydride. Taken together, these results suggest that although the nucleocapsids appear as closed loops, the viral RNA has free 5' and 3' ends and is, therefore, not circular.
Purification and composition of the proteins from Sindbis virus grown in chick and BHK cells
Authors: Burke D J , Keegstra K
Published: January 2020

Procedures are described for the purification of the Sindbis virus structural proteins. The amino acid and carbohydrate compositions of the purified proteins are presented for virus grown in BHK-21/13 and chicken embryo cells. Glycoprotein E1 from virus grown in BHK cells is deficient in a mannose-rich glycopeptide found on that glycoprotein when virus is grown in chicken embryo cells. The complex glactose-containing glycopeptides appear similar for virus grown in both hosts. However, when virus is grown in BHK cells, both glycoproteins are enriched in those glycopeptides containing more sialic acid. Since the two viral glycoproteins are difficult to separate cleanly during purification, it is suggested that there may be strong, but noncovalent, interactions between glycoproteins E1 and E2. It is also suggested that there may be an interaction between glycoprotein E2 and a component of the nucleocapsid.
L cell virus: infectivity for type N and B mouse embryo cells
Authors: Botis S , Janowski M , Maisin J R
Published: January 2020

The efficiency of focus formation of four L cell virus populations was significantly higher on type N mouse embryo fibroblast cultures than on type B cells. [5-3H]uridine-incorporating material sedimenting at a density of 1.158/g/cm3 was observed in the supernatant fluids of type N and B cultures infected with the four viral populations.
Rate of divergence of cellular sequences homologous to segments of Moloney sarcoma virus
Authors: Frankel A E , Fischinger P J
Published: January 2020

The RNA genome of the Moloney isolate of murine sarcoma virus (M-MSV) consists of two parts--a sarcoma-specific region with no homology to known leukemia viral RNAs, and a shared region present also in Moloney murine leukemia virus RNA. Complementary DNA was isolated which was specific for each part of the M-MSV genome. The DNA of a number of mammalian species was examined for the presence of nucleotide sequences homologous with the two M-MSV regions. Both sets of viral sequences had homologous nucleotide sequences present in normal mouse cellular DNA. MSV-specific sequences found in mouse cellular DNA closely matched those nucleotide sequences found in M-MSV as seen by comparisons of thermal denaturation profiles. In all normal mouse cells tested, the cellular set of M-MSV-specific nucleotide sequences was present in DNA as one to a few copies per cell. The rate of base substitution of M-MSV nucleotide sequences was compared with the rate of evolution of both unique sequences and the hemoglobin gene of various species. Conservation of MSV-specific nucleotide sequences among species was similar to that of mouse globin gene(s) and greater than that of average unique cellular sequences. In contrast, cellular nucleotide sequences that are homologous to the M-MSV-murine leukemia virus "common" nucleotide region were present in multiple copies in mouse cells and were less well matched, as seen by reduced melting profiles of the hybrids. The cellular common nucleotide sequences diverged very rapidly during evolution, with a base substitution rate similar to that reported for some primate and avian endogenous virogenes. The observation that two sets of covalently linked viral sequences evolved at very different rates suggests that the origin of M-MSV may be different from endogenous helper viruses and that cellular sequences homologous to MSV-specific nucleotide sequences may be important to survival.
Photodynamic treatment of herpes simplex virus during its replicative cycle
Authors: Khan N C , Melnick J L , Biswal N
Published: January 2020

Photodynamic treatment of herpes simplex virus type 1-infected hamster embryo fibroblasts (LSH strain) with a low concentration of proflavine (0.08 mug/10(5) cells per ml), a 3-9-diamine acridine dye, inhibited production not only of infectious progeny but also of virion particles. However, there was no appreciable inhibition of viral or cellular DNA synthesis, even when the infected cells were repeatedly exposed to this low concentration of dye and light during the replication cycle of the virus. It thus appears that photodynamic treatment of infected cells interferes with the processes involved in virus maturation.
Virus-specific protein synthesis in cells infected by infectious pancreatic necrosis virus
Authors: Dobos P
Published: January 2020

A study of virus-specific protein synthesis in infectious pancreatic necrosis virus-infected RTG-2 cells was undertaken to find a relationship between the coding capacity of virus genome (two segments of double-stranded RNA of 2.5 X10(6) and 2.3 X 10(6) molecular weight) and the sizes and relative amounts of polypeptides in the virion and in infected cells. The time course of virus-specific protein synthesis was followed by pulse labeling infected UV-irradiated cells with [35S]methionine and analyzing the labeled proteins by polyacrylamide gel electrophoresis followed by autoradiography. Three size classes of virus-specific polypeptides were synthesized, in the same relative proportion, throughout the infectious cycle, beginning 3 h postinfection. Their designation and molecular weight was as follows: alpha1, 1000,000; alpha2, 90,000; beta1, 59,000; beta2, 56,000; gamma1, 32,000; gamma2, 30,000; and gamma3, 28,000. Experiments using amino acid analogues, protease inhibitors, ZnCl2, and supraoptimal temperatures showed that polypeptides of the beta and gamma families did not arise from the alpha polypeptides by post-translational cleavage. Slow cleavage late in the infectious cycle could be demonstrated, since during 12-h period radioactivity was chased from beta1 via beta3 to beta4 (molecular weight 50,000) and beta5 (molecular weight, 49,000). During the chase most of gamma2 was degraded, whereas radioactivity could not be chased from the remaining virus-specific polypeptides. Purified virus contained polypeptides alpha1, alpha2, beta4, beta5, and gamma1. The beta polypeptides made up over 60% of the virion proteins. The results suggest that infectious pancreatic necrosis vibrus possesses a unique mechanism for synthesis of three size-classes of proteins using mRNA transcripts from two high-molecular-weight double-stranded RNA genome segments.
Inhibition of host cell protein synthesis by UV-inactivated poliovirus
Authors: Helentjaris T , Ehrenfeld E
Published: January 2020

The ability of poliovirus that was irradiated with UV light at energies up to 2,160 ergs/mm2 to subsequently inhibit host cell protein synthesis was measured. The inactivation of the host cell shutoff function followed one-hit kinetics. Increasing irradiation did not affect the rate of inhibition until the multiplicity of infection after irradiation was reduced to approximately 1 PFU/cell. At higher functional multiplicities, the rate was unchanged, but an increasing lag before the onset of inhibition was observed with increasing irradiation. The energy levels required to inactivate virus-induced inhibition of host cell protein synthesis suggest that damage to virus RNA rather than to virus capsid proteins is responsible for the loss of function. When the inactivation of host cell shutoff was compared with the inactivation of other viral functions by UV irradiation, it correlated exactly with the loss of infectivity but not with other viral functions measured. Guanidine treatment, which prevents detectable viral RNA and protein synthesis, completely inhibited host cell shutoff by low multiplicities of unirradiated virus infection but not higher multiplicities. When a high multiplicity of virus was first reduced to a low titer by irradiation, host cell shutoff was still evident in the presence of guanidine. The results demonstrate that the complete inhibition of host cell protein synthesis can be accomplished by one infectious viral genome per cell.
Expression of an early, nonstructural antigen of herpes simplex virus in cell transformed in vitro by herpes simplex virus
Authors: Flannery V L , Courtney R J , Schaffer P A
Published: January 2020

Hyperimmune rabbit antiserum to an early, nonstructural herpes simplex virus type 2 (HSV-2)-induced polypeptide (VP143) reacted in immunofluorescence tests with a variety of cell lines transformed by HSV-2. Cytoplasmic fluorescence was observed in 10 to 50% of HSV-2-transformed cells, whereas no fluorescence was observed in cells transformed by other oncogenic DNA viruses or by a chemical carcinogen. VP143-specific reactivity could be absorbed from anti-VP143 serum with HSV-2-transformed cells but not with cells transformed by other agents. When HSV-2-transformed cells were synchronized in mitosis and examined at various times postmitosis for VP143-specific fluorescence, the expression of VP143 was shown to be cell cycle dependent.
Role of carbohydrate in biological functions of Friend murine leukemia virus gp71
Authors: Schäfer W , Fischinger P J , Collins J J , Bolognesi D P
Published: January 2020

Purified gp71 of Friend murine leukemia virus (FLV) can interfere with virus infection, absorb neutralizing antibody, and in the presence of group-specific anti-gp71 antibody, hemagglutinate sheep erythrocytes. Interference by FLV gp71 with several murine leukemia viruses (MuLV) was tested in the XC and S + L- assay systems. Treatment of gp71 with trypsin or Pronase eliminated its interfering capacity. However, treatment with neuraminidase or a mixture of glycosidase enzymes, which left the major serological properties of gp71 intact, did not reduce the interference potential of gp71 for FLV or AKR MuLV. The capacity of gp71 to absorb type- or group-specific virus-neutralizing antibodies was similarly affected by the various enzyme treatments. In contrast, indirect hemagglutination by gp71 was abolished not only by proteases but also by treatment with glycosidase enzymes, although neuraminidase had no effect. Preliminary data indicate that infectivity of FLV or xenotropic MuLV was not affected by short treatment with glycosidase enzymes.
DNA contained by two densonucleosis viruses
Authors: Kelly D C , Barwise A H , Walker I O
Published: January 2020

The DNA contained by particles of densonucleosis viruses 1 and 2 were analyzed within the particle, and properties of DNA extracted from these particles were determined. The DNA appears to exist as a single-stranded molecule with limited secondary structure within particles, as assessed by spectral changes induced by formaldehyde, melting profiles, and circular dichroism studies. The single-stranded DNA had an apparent molecular weight of 1.9 X 10(6) to 2.2 X 10(6) as assessed by differences in the molecular weight of virus particles and top component and percentage of nucleic acid. DNA extracted from virus particles in low-salt buffers possessed properties typical of a single-stranded molecule. Double-stranded DNA could be extracted from virus particles under appropriate high salt and elevated temperature. The linear double-stranded DNA extracted from both viruses had a molecular weight of about 3.9 X 10(6) to 4.1 ZX 10(6) determined by neutral sedimentation and electron microscopy and an equivalent genome size determined by reassociation kinetics. About 87% of the DNA was homologous between the two viruses.
Rifampin-susceptible mutant of vesicular stomatitis virus: protein and RNA synthesis
Authors: Moreau M C , Sanzey B
Published: January 2020

A rifampin-susceptible strain (VSV Rif+) was selected from the wild vesicular stomatitis virus (VSV) population unsusceptible to rifampin. The VSV Rif+ was blocked in its intracellular replication in the presence of rifampin. In cells, rifampin affected primarily VSV Rif+ transcription, but to a different extent than in a cell-free system. In addition, a decrease in the amount of VSV Rif+ protein M was detected, linked to a stimulation of protein NS. In the absence of rifampin, protein M, although synthesized, was not immediately incorporated into the cell membrane. An interpretation of these observations is proposed.