bluuebunny/crossref_metadata_2025 huggingface dataset:
Intracisternal A particles from FLOPC-1 BALB/c myeloma: presence of high-molecular-weight RNA and RNA-dependent DNA polymerase
Authors: Krueger R G
Published: January 2020

Intracisternal A particles from the FLOPC-1 line of BALB/c myeloma have been shown to contain high-molecular-weight RNA (60 to 70S) that is sensitive to RNase, alkali degradation, and heat but resistant to Pronase treatment. The intracisternal A-particle RNA contains tract of poly (A) approximately 180 nucleotides long. As shown in a reconstitution experiment, by antigenic analysis of A-particle preparation and the SC cytopathogenicity assay, the 70S RNA was not due to contamination by type C virus particles. The FLOPC-1 intracisternal A particles also possess an endogenous RNA-dependent DNA polymerase. The enzyme required Mn2+ or Mg2+, dithiothreitol, detergent, and four deoxyribonucleoside triphosphates for maximum activity. Enzymatic activity was maximally stimuated by poly (rC)-oligo (dG)12-18 and less with poly (rG)-oligo (dC)10 or poly (rA)-oligo (dT)12-18 as compare with synthetic DNA/DNA duplex templates such as poly (dA)-oligo (dT)12-18. The enzyme can utilize the A-particle endogenous RNA as template as shown by analysis of the early and late DNA products of the endogenous reaction by CsSO4 isopycnic gradient centrifuation and hybridization of purified 70S or 35S A-particle RNA with the purified complementary DNA product. Approximately 50% of the A-particle complementary DNA also hybridized with oncornavirus RNA.
Restriction endonuclease from Haemophilus gallinarum (HgaI) cleaves polyoma DNA at four locations
Authors: Shishido K , Berg P
Published: January 2020

A restriction endonuclease obtained from Haemophilus gallinarum (hgaI) cleaves polyoma DNA at four specific sites. Using the EcoRI, HindIII, and HpaII endonuclease restriction sites as reference, the four HgaI cleavage sites were mapped at 0.02, 0.14, 0.27, and 0.48 fractional lengths, clockwise, from the single EcoRI cleavage site.
Replication of human cytomegalovirus DNA: lack of dependence on cell DNA synthesis
Authors: DeMarchi J M , Kaplan A S
Published: January 2020

Human cytomegalovirus (CMV) DNA synthesis was studied in 5-fluorouracil (FU)-treated and untreated human embryonic lung cells, which differ greatly with respect to the number of cells in the culture synthesizing cellular DNA. CMV DNA synthesis proceeded at the same rate in FU-treated and in untreated cells. CMV infection also reversed the inhibitory effects of FU and activated cellular DNA synthesis in some of the cells in the FU-treated culture. Autoradiographic studies showed that more than 20% of the cells in the infected FU-treated culture synthesized viral DNA when less than 1% had synthesized cellular DNA, indicating that the synthesis of viral macromolecules proceeds in cells that do not synthesize cellular DNA from the time of infection, and that viral DNA synthesis proceeds independently of the host cell DNA synthesis. Combined autoradiographic and immunofluorescence studies of both the FU-treated and untreated infected cells showed that, whereas 20% of the cells in the cultures synthesize viral DNA and viral antigens, only about 3 to 6% of those cells that synthesize cellular DNA also synthesize viral antigen. Thus, productive infection was delayed or inhibited in those cells that were stimulated by CMV infection to synthesize cellular DNA.
Construction of the genetic map of the polyoma genome
Authors: Miller L K , Fried M
Published: January 2020

Seven early mutants, three late mutants, and one plaque morphology mutant of polyoma have been mapped by marker rescue using wild-type restriction endonuclease fragments. The early mutants map between 1.0 and 26.4 units from the Eco RI site, a region previously shown to correspond to the 3'-OH termainal half of "early" RNA (Kamen et al., 1974). The late mutants as well as the plaque morphology mutant map between 26.6 and 45.4 map units, a region previously shown to correspond to the 3'-OH terminal half of "late" RNA (Kamen et al., 1974). Analysis of the genotype of rescued virus demonstrated that the modification of the mutant DNA during marker rescue was limited to the region of the genome covered by the wild-type restriction endonuclease fragment tested.
RNA composition of Junin virus
Authors: Añón M C , Grau O , Segovia Z M , Franzefernández M T
Published: January 2020

Junin virus grown in BHK-21 cells was labeled with [3H]uridine and highly purified by differential and isopycnic centrifugation. The RNAs extracted with phenol and analyzed by polyacrylamide gel electrophoresis were shown to be composed of four large species (33, 28, and 18S) and three small ones (4, 5, and 5.5S). This pattern was similar to ones already reported for other arenaviruses. However, there was a striking difference when the virus labeling was performed in the presence of actinomycin D. Labeling of viral rRNA was as much as 60% of the levels obtained in the absence of the drug under conditions in which cellular rRNA's were inhibited by 95% or more.
Mutant of herpes simplex virus type 1 conditionally able to transform thymidine kinaseless L cells to a tk+ phenotype
Authors: Hughes R G , Munyon W H
Published: January 2020

After nitrous acid mutagenesis of herpes simplex virus type 1 (HSV-1), a mutant, 1093, was isolated which, during productive infection, induced very low levels of thymidine kinase (tk). The mutant virus was found, after UV irradiation, to be unable to transform L cells lacking tk (Ltk-) to a tk+ phenotype as chararcterized by growth of the cells in a modified HAT-selective medium containing 1.6 X 10(-5) M thymidine. Cells transformed by wild-type virus grew vigorously under the same conditions. The mutant was able to transform Ltk- cells if the medium contained 10(-3) M thymidine. These transformed cells maintained their conditional character and would not grow in low concentrations of thymidine in selective medium. Therefore, this mutant is conditional on the thymidine concentration in the selection medium in its ability to transform Ltk- cells to a tk+ phenotype. The conditionally transformed cells could be supertransformed with wild-type UV-irradiated HSV-1 to a phenotype which would grow in low-thymidine selective medium. The frequency of supertransformation closely approximated the frequency of transformation of Ltk- cells by wild-type virus. Supertransformation at high frequency could not be effected by mutant 1093 or the tk- mutant B2006. These results indicate that the presence of HSV-1 genetic information in HSV-1-transformed cells does not preclude the acquisition by these cells of at least one additional HSV-1 gene, that for tk.
Herpes simplex virus DNA in transformed cells: sequence complexity in five hamster cell lines and one derived hamster tumor
Authors: Frenkel N , Locker H , Cox B , Roizman B , Rapp F
Published: January 2020

Analyses of the hybridization kinetics of labeled herpes simplex virus 2 (HSV-2) DNA with DNA from five hamster cell lines transformed by UV light-irradiated HSV-2 revealed the following. (i) Viral DNA sequences were detected in all five cell lines tested. (ii) None of the cell lines contained the full complement of HSV-2 DNA. (iii) The amount of viral DNA present in the cells varied in different transformed cell lines and ranged from 8 to 32% of the HSV-2 DNA genome in 1 to 3 copies/cell. (iv) Two parallel passages of the same cell line (333-2-29) differed in the amount of viral DNA they contained. We also compared the viral DNA sequences present in (i) one transformed cell line (333-8-9) propagated serially in culture for 80 passages, (ii) a tumor produced by inoculation of a newborn hamster with the 333-8-9 cells, and (iii) a cell line derived from a hamster tumor as above and propagated in culture for 32 passages. The results show that viral DNA present in the hamster tumor and in the cells derived from the tumor had a lower sequence complexity than that present in the original serially passaged 333-8-9 cell line.
Relationship of Friend murine leukemia virus production to growth and hemoglobin synthesis in cultured erythroleukemia cells
Authors: Sherton C C , Evans L H , Polonoff E , Kabat D
Published: January 2020

The factors that control oncornavirus formation were analyzed in Friend leukemia cells that undergo hematopoiesis when treated with dimethyl sulfoxide. Suspension cultures of Ostertag FSD-1 cell line were found to enter a G or resting state at the end of their proliferative phase and to simultaneously cease producing helper and dependent components of Friend virus. Whereas the decline in virus production is at least 100-fold, rates of cellular RNA and protein synthesis are only slightly lower in resting than in growing cells. Both resting and growing cells contain similarly large concentrations of the viral proteins P(30) and P(12). Dimethyl sulfoxide induces hemoglobin synthesis in growing cells, but its effects on virus production appear to be indirect results of its action to inhibit cell growth and thus to delay entry of cells into the G resting state. Furthermore, variant cell lines were obtained with differing abilities to synthesize virus or hemoglobin. Some lines no longer produce infectious virus, although they all harbor murine leukemia virus genes which are expressed to varying extents. The major internal protein of these oncornaviruses, P(30), is synthesized in large amounts by all of the cell lines. These results suggest that Friend virus production is not coinduced with erythroid differentiation, as had been proposed, but rather is controlled by a cellular growth cycle.
Characterization and genetic mapping of nontoxinogenic (tox) mutants of corynebacteriophage beta
Authors: Holmes R K
Published: January 2020

Seven new nontoxinogenic (tox) mutants of corynebacteriophage beta were isolated. Strains of Cornyebacterium diphtheriae C 7 lysogenic for these tox mutants of beta were tested for their ability to produce extracellular diphtherial toxin or proteins (CRMs) that cross-react immunologically with toxin. By using a sensitive reversed passive hemagglutination assay for toxin antigen, three of the tox mutants were phenotypically CRM+ and four were CRM-. The molecular weights of the CRMs produced by mutants beta tox-1, beta tox-2, and beta tox-3 were determined to be approximately 20,000, 26,000, and 34,000, respectively, by electrophoresis in polyacrylamide gels containing sodium dodecyl sulfate. The 26,000 and 34,000-dalton CRMs had nicotinamide adenine dinucleotide: elongation factor 2 adenosine diphosphate ribose transferase activity, but the 20,000-dalton CRM did not. These three CRMs correspond to amino-terminal fragments of diphtherial toxin and appear to be formed by chain termination during protein synthesis directed by phages with nonsense mutations in the structural gene for diphtherial toxin. No complementation was observed between independently isolated tox mutants of phage beta. The positions of four tox markers on the vegetative genetic map of phage beta were determined, and the orientation of transcription of the structural gene for diphtherial toxin with respect to other markers on the genetic map of phage beta was established.
Comparative Membrane Microviscosity of Fish and Mammalian Rhabdoviruses Studied by Fluorescence Depolarization
Authors: Moore Norman F. , Barenholz Yechezkel , McAllister Philip E. , Wagner Robert R.
Published: January 2020

The microviscosity of the hydrophobic region of the membrane of infectious hematopoietic necrosis virus was determined using fluorescence depolarization analysis of the probe 1,6-diphenyl-1,3,5-hexatriene and was found to be much lower at 37 C than that of another rhabdovirus, vesicular stomatitis virus. However, the microviscosity of this fish virus at 18 C, the temperature at which it was grown, corresponded to the microviscosity of vesicular stomatitis virus at 37 C. Data obtained with the fish virus host cell (chinook salmon embryo cells) grown at 18 C suggest that its membranes have a lower microviscosity than either L-929 or BHK-21 cells (the vesicular stomatitis virus host cells) grown at 37 C.
Phospholipid metabolism in Pseudomonas BAL-31 infected with lipid-containing bacteriophage PM2
Authors: Diedrich D L , Cota-Robles E H
Published: January 2020

Infection of Pseudomonas BAL-31 with the lipid-containing bacteriophage PM2 resulted in no detectable change in the rate of phosphatidylglycerol (PG) or phosphatidylethanolamine (PE) biosynthesis. An increase in the PG content of infected cultures was not seen until the cultures began to lyse, and this increase was in fact only a relative increase resulting from the extensive turnover of PE at the onset of culture lysis. Turnover studies revealed that the glycerol, phosphorus fatty acid, and ethanolamine moieties of PE turned over simultaneously at the time of lysis, and therefore made it unlikely that there was a PE to PG conversion during the latent period of the phage. The lipid found in the bacteriophage did not reflect a preferential selection for lipid synthesized before or after infection, but in fact reflected the composition of the host membrane at the time the phage were assembled. The use of a modified medium that allowed the cultivation of Pseudomonas BAL-31 as a prototroph and resulted in reliable lysis times of infected cultures led us to the conclusion that PM2 infection effects little change in host phospholipid metabolism, and that there is sufficient PG in the host cytoplasmic membrane to account for a full burst of phage. As a result of the reliable lysis times that we have achieved, we concluded that certain metabolic events, i.e., PE turnover, are lytic phenomena and must not be confused with events relevant to the biosynthesis and maturation of the phage.
Association of the polioviral RNA polymerase complex with phospholipid membranes
Authors: Butterworth B E , Shimshick E J , Yin F H
Published: January 2020

Polioviral RNA polymerase complex, which consists of enzyme, template, and nascent RNA, is membrane bound in vivo. The solubilized RNA polymerase complex associated spontaneously in vitro with phospholipid bilayer membranes (liposomes) of defined composition. The degree of association at 37 degrees C was greater for those membranes that were more fluid, suggesting that the binding involves the interaction of the RNA polymerase complex with the hydrocarbon chains in the interior of the lipid bilayer. The polymerase activity was not enhanced by addition of the lipid; in fact, the addition of some of the longer-chain lipids resulted in up to a 40% inhibition of the polymerase activity. Spin-label electron paramagnetic resonance experiments, which measured the membrane fluidity, and kinetic experiments on the rate of incorporation of tritiated UTP into RNA by the polymerase were performed as a function of temperature. The results indicated that the activity of the polymerase was not affected by the physical state of the phospholipid membrane and that its active site was not intimately associated with the membrane. Analysis of both the viral and host polypeptides associated with the smooth membrane-bound polymerase indicated that X was the primary viral polypeptide present. In addition, host polypeptides of molecular weight 86,000, 62,000, 54,000, and 46,000 were also present. If the membrane was disrupted with detergent, polypeptide X was released from the polymerase activity, suggesting that X may play a role in binding the polymerase to the membrane. In an analogous manner, polypeptide X associated spontaneously with phospholipid membranes to a greater extent than the capsid polypeptides. Analysis of both the host and viral polypeptides associated with the viral RNA polymerase purified by precipitation in 2 M LiCl indicated that host polypeptides of molecular weight 106,000, 38,000, 33,000, and 14,000 were the major constituents, whereas relatively small amounts of the viral polypeptides were present. It was confirmed that of the viral polypeptides found, polypeptide 4 was present in the largest amount.
Utilization of early promotors in mutant far P85 of bacteriophage T4
Authors: Sauerbier W , Hercules K , Hall D H
Published: January 2020

We show that farP85 is a recessive mutant of T4 incapable of activating the delayed early promotors for genes 43 and 45 and that the farP85 mutation is in the same complementation group as the ts G1 mutation, which is located in the "modifier of transcription" (mot) gene.
Characterization of the Tumorlike (T) Antigen Induced by Type 12 Adenovirus
Authors: Gilead Z. , Ginsberg H. S.
Published: January 2020

T antigen, purified from KB cells infected with type 12 adenovirus, was characterized by chemical and physical methods. The immunologically active molecule had an ultraviolet-absorption spectrum characteristic of a protein, and was partially inactivated (i.e., approximately 85%) by trypsin (final concentration of 150 μg/ml). Centrifugation analyses indicated that the purified antigen was a single molecular species with an average sedimentation coefficient of 2.40
S
(measured by zonal centrifugation in sucrose gradients) and an
S
20,w
of 2.58 determined by analytical centrifugation. The antigen was inactivated at temperatures above 40 C, it was stable between
p
H 5.7 and 8.8, and it had an isoelectric point of approximately 5.0, as determined by electrophoresis on cellulose polyacetate membranes.
Deoxyribonucleic Acid-dependent Ribonucleic Acid Polymerase Activity in Cells Infected with Influenza Virus
Authors: Borland R. , Mahy B. W. J.
Published: January 2020

Deoxyribonucleic acid (DNA)-dependent ribonucleic acid (RNA) polymerase activity was assayed on nuclear preparations of chick embryo fibroblast cells at various times after infection with an influenza A virus (fowl plague virus) and was compared with the activity of uninfected cells. Polymerase activity was increased by about 60% by 2 hr after infection, and this increase coincided with an increase in RNA synthesis in infected cells, as determined by pulse-labeling with uridine. No difference could be detected between the polymerases of infected and uninfected cells as to their requirements for DNA primer, divalent cations, and nucleoside triphosphates, and they were equally sensitive to addition of actinomycin D to the reaction mixture. It is possible that host cell DNA-dependent RNA polymerase is involved in the replication of influenza virus RNA.
Characterization of the Tumorlike (T) Antigen Induced by Type 12 Adenovirus
Authors: Gilead Z. , Ginsberg H. S.
Published: January 2020

The T antigen induced by type 12 adenovirus was purified from KB cells infected in the presence of 10
−6
m
5-fluoro-2-deoxyuridine to inhibit synthesis of viral capsid antigens. The antigen was purified approximately 200-fold, and the purified product contained only negligible amounts of host-cell contaminants, as judged by the residual radioactivity from
14
C-labeled uninfected cells which had been added to infected cells at the initiation of the purification. Immunoelectrophoresis indicated that the purified T-antigen preparation contained a single antigenic species. The T antigen from a hamster cell line (HT-1) derived from a type 12 adenovirus-induced tumor was purified by the same procedure. The T antigens from the two different sources were shown to be immunologically similar by use of a rabbit antiserum prepared against the purified T antigen from infected KB cells and sera from hamsters bearing tumors induced by type 12 adenovirus.
Biochemical Studies on Adenovirus Multiplication XIII. Synthesis of Virus-Specific Ribonucleic Acid During Infection with Human Adenovirus Type 12
Authors: Mak Stanley , Green Maurice
Published: January 2020

The transcription of virus-specific ribonucleic acid (RNA) was studied in KB cells infected with adenovirus type 12 (strain Huie). Viral deoxyribonucleic acid (DNA) synthesis began at 12 to 15 hr after infection, and virus maturation occurred between 20 and 50 hr after infection. The rate of incorporation of
3
H-uridine into RNA per infected cell was stimulated, reaching a maximum of 1.6 times that of uninfected cells at 20 hr after infection. “Early” viral messenger ribonucleic acid (mRNA) constituted 0.1% of RNA synthesized at 11 hr, and “late” viral mRNA constituted 50% of RNA synthesized at 45 hr after infection, as determined by hybridization of viral DNA with labeled RNA from infected cells pulse labeled with
3
H-uridine. The species of virus-specific RNA synthesized at 22 hr after infection (when virus maturation has just begun) and at 45 hr (when virus maturation is nearly complete) were studied further: (i) 22- and 45-hr RNA had the same average guanine plus cytosine content, 47%, (ii) 22- and 45-hr RNA contained mostly the same viral nucleotide sequences, (iii) 45-hr RNA had a five times higher concentration of virus-specific RNA molecules than did 22-hr RNA, and (iv) 22- and 45-hr RNA contained virus-specific nucleotide sequences transcribed from all, or nearly all, of the viral genome.
Effects of X-irradiated Aqueous Solutions on Vesicular Stomatitis Virus
Authors: Heine J. W. , Galasso G. J.
Published: January 2020

Infectivity of vesicular stomatitis virus was inactivated by suspending the virus in aqueous salt solutions that had previously been subjected to X-irradiation. This viral inactivation did not appear to be attributable to hydrogen peroxide or to long-lived free radicals generated by X-irradiation of the salt solutions. Indirect evidence suggested that the deleterious effects on the virus were caused by chemical species resulting from interaction of free water molecules with anions in the solution. Inactivation of infectivity was associated with distortion of the outer layer of the virion, as determined by electron microscopy, and with consequent impairment of adsorption to otherwise susceptible cells.
Electron Microscopic Study of the Morphogenesis of Vesicular Stomatitis Virus
Authors: Hackett A. J. , Zee Y. C. , Schaffer F. L. , Talens L.
Published: January 2020

Except for the rate, vesicular stomatitis virus (VSV) grows as well at 25 C as at 37 C in primary chick embryo fibroblast cells and in a pig kidney cell line [PK(H13)]. Maximal yields were reached at about 28 hr at 25 C and 10 hr at 37 C in these cells. Morphogenesis, as observed by electron microscopy, was similar at the two temperatures. The main feature was accumulation of virus in intracytoplasmic vacuoles. Mode of release of VSV has been controversial; both budding (as displayed by myxoviruses) and maturation at membranes of cytoplasmic vacuoles (as with arboviruses) have been claimed. Our observations support the latter view, and the apparent dichotomy in interpretation is discussed.
Origin of Phospholipid in Bacteriophage PM2
Authors: Espejo Romilio T. , Canelo Eliana S.
Published: January 2020

Phosphatidylethanolamine is the only phosphatide present in purified bacteriophage PM2 when obtained from bacteria grown and infected in minimal medium. The growth cycle of bacteriophage PM2 shows the basic general features described for virulent bacteriophages. PM2 infection of
Pseudomonas
BAL-31 causes a pronounced increase in deoxyribonucleic acid synthesis, but no detectable effect on the incorporation of phosphorus into lipid. When
32
P-prelabeled bacteria are infected with PM2, the specific activity of the phosphatide phosphorus in the virus is almost the same as that in the host bacteria labeled before infection. It is concluded that the viral phosphatide is not synthesized de novo after infection, but it probably is derived from preexisting cellular phosphatidylethanolamine.
Effect of Formamide on the Capsid Morphology of Adenovirus Types 4 and 7
Authors: Stasny John T. , Neurath A. Robert , Rubin B. A.
Published: January 2020

Treatment of adenovirus types 4 and 7 with formamide disrupted the virions, degrading the capsids into predominantly single capsomers. As shown by electron microscopic observation, disruption proceeded in the following sequence: (i) reduction of the electron density of the virions, suggesting release of an internal component; (ii) progressive cleavage of the capsid into two or more segments and the formation (type 7 only) of capsomer “sheets”; (iii) final cleavage of the capsid into single or groups of a few capsomers. The sequence appeared similar for both adenoviruses; for both types, the rate and extent of disruption were dependent on the formamide concentration, but type 7 was more easily disrupted than type 4 by short-term (5 to 10 sec) treatment at the low (10%) concentration. At 30% formamide, the intercapsomer bonds of either type were fully cleaved, and the capsids were completely degraded into predominantly single capsomers. Pretreatment with formaldehyde did not prevent this degradation. Under suitable conditions, virus-derived remnants can be observed among the breakdown products. These remnants have been shorn of capsomers and presumably represent intact internal nucleoprotein.
Infection of Competent
Mycobacterium smegmatis
with Deoxyribonucleic Acid Extracted from Bacteriophage B1
Authors: Tokunaga Tohru , Nakamura Reiko M.
Published: January 2020

A relatively competent state of
Mycobacterium smegmatis
for infection with deoxyribonucleic acid (DNA) extracted from phage B1 was found in the late log phase of bacterial growth. This state of the culture was used in quantitative studies on the infectivity of the DNA. The buoyant density of B1 DNA was 1.728 g/cc in CsCl, and 1 μg of the DNA produced 84 infective centers, the phage equivalent of which was 1.5 × 10
−8
. The infectivity was destroyed by catalytic amounts of deoxyribonuclease but not by specific B1 antiserum. Tween 80, which prevents phage adsorption, did not prevent DNA infection. The response of plaque-forming ability to DNA concentration suggested that two or more molecules are required to initiate an infective center. The low efficiency of DNA infection in mycobacteria was considered to be caused by a limiting population of competent cells in the culture employed; in this experiment less than 10
−5
of the cells were infected with DNA. A typical cycle of infection was observed, although the latent period was prolonged and the burst size reduced after DNA infection. The transition of B1 DNA infection to deoxyribonuclease insensitivity had a lag period of about 10 min, and increased linearly with a velocity of about 0.24 infective centers per min per μg of DNA. Half of the infective titer was inactivated by heating at 92 C for 15 min. The melting temperature was about 96 C. Species barriers were not crossed by B1 DNA; however, the DNA was infectious for a B1-resistant mutant of the host.
Replication of Bacteriophage Ribonucleic Acid: Analysis of the Ultrastructure of the Replicative Form and the Replicative Intermediate of Bacteriophage R17
Authors: Granboulan Nicole , Franklin Richard M.
Published: January 2020

A detailed qualitative and quantitative comparison was made of the ultrastructure of single-stranded ribonucleic acid (RNA) from bacteriophage R17 and double-stranded replicative form (RF) and replicative intermediate (RI) from cells infected with this bacteriophage. The nucleic acids were prepared for electron microscopy by the protein monolayer spreading technique of Kleinschmidt. Single-stranded RNA aggregated during spreading in the absence of urea, whereas RF and RI did not. On the other hand, RF and RI appeared to be susceptible to shear during spreading, whereas R17 RNA was not. From the maximal length of RF, a base translation of 3.14 A was calculated. This value favors a 10-fold helix model of double-stranded RNA. The same base translation was found for R17 RNA, indicating a stacked base structure for single-stranded RNA spread in the presence of urea. RI is a branched structure and the branches are removed by ribonuclease treatment. The branches are believed to be nascent single-stranded viral RNA. The contour length of the branch was equal to the contour length of the main chain up to the branch point, as predicted from theoretical analysis of the replication of viral RNA. The structure of RF and the main chain of RI was also analyzed by plotting the log (end-to-end distance squared) versus log (contour length). This demonstrated structures intermediate in stiffness between a random coil and a rigid rod.
Transcription of the Genomes of Type 1 and Type 3 Reoviruses
Authors: Prevec L. , Watanabe Y. , Gauntt C. J. , Graham A. F.
Published: January 2020

The double-stranded ribonucleic acid (RNA) genome of type 1 reovirus was fragmented into three size classes on extraction, as has already been shown for reovirus type 3. The relative amounts and molecular weights of the three classes were the same for the two viruses. Cells infected with type 1 virus synthesized three classes of messenger RNA. Each class of messenger RNA hybridized exclusively with a denatured double-stranded RNA fragment of equivalent length, as had also been found for type 3 reovirus. The double-stranded RNA segments thus act as specific units for transcription of messenger RNA in the infected cells. In cells infected with type 3 reovirus, the three classes of messenger RNA are made in equal amounts throughout the course of multiplication. In contrast, cells infected with type 1 virus produced only half as much of the largest messenger RNA as they did of the other two classes at all times during the replicative cycle. This finding suggests that transcription of the largest segments of type 1 viral genome is restricted.
Replication of T4rII Bacteriophage in
Escherichia coli
K-12 (λ)
Authors: Buller Clarence S. , Astrachan L.
Published: January 2020

The defect of T4rII replication in
Escherichia coli
K-12 (λ) can be phenotypically reversed by various supplements to the growth medium. Arginine, lysine, spermidine, and a number of diamines allowed varying levels of rII replication. The best reversion was obtained with 0.4
m
sucrose in 0.002 to 0.005
m
Ca
++
. Monovalent cations severely inhibited reversion. A cell surface site of polyamine action is consistent with the fact that spermidine inhibits phage ghost-induced cell lysis and with the finding that sufficient polyamine is available within the cells to allow normal patterns of neutralization of phage deoxyribonucleic acid, as detected by the polyamine content of progeny phage. In the absence of effective supplements, rII-infected cells swelled and lost refractility. The data indicate that a leaky cell envelop is involved. No difference in mucopeptides of uninfected K-12 (λ) and K-12 was detected and, because the mucopeptide in r
+
infected cells was found to be at least partially hydrolyzed midway through the lytic cycle, it did not appear that the rII defect concerned mucopeptide synthesis. The pattern of cell phospholipid synthesis changes after phage infection, but no difference was detected between r
+
and rII with regard to biosynthesis of phosphatidylethanolamine and phosphatidylglycerol.
Host-controlled Restriction of T-even Bacteriophages: Relation of Four Bacterial Deoxyribonucleases to Restriction
Authors: Eigner Joseph , Block Stephen
Published: January 2020

Escherichia coli
strains B and K-12, which restrict growth of nonglucosylated T- even phage (T
*
phage), and nonrestricting strains (
Shigella sonnei
and mutants of
E. coli
B) were tested for levels of endonuclease I and exonucleases I, II, and III, by means of in vitro assyas. Cell-free extracts freed from deoxyribonucleic acid (DNA) were examined with three substrates:
E. coli
DNA, T
*
2 DNA, and T2 DNA. Both restricting and nonrestricting strains had comparable levels of the four nuclease activities and had similar patterns of preference for the three substrates. In addition, mutants of
E. coli
B and K-12 that lack endonuclease I were as effective as their respective wild types in restricting T
*
phage.
Demonstration of a Herpes Group Virus in Cultures of Peripheral Leukocytes from Patients with Infectious Mononucleosis
Authors: Diehl Volker , Henle Gertrude , Henle Werner , Kohn Gertrude
Published: January 2020

Cultures were initiated with peripheral leukocytes from individuals: (i) in the acute stage of infectious mononucleosis (IM); (ii) with past histories of IM; and (iii) without histories of IM and without antibodies to EB virus (EBV). In confirmation of other reports, the first group of cultures developed readily and rapidly into lines of blastoid cells. Cellular replication commenced in 24 of 25 attempts within 17 to 28 days, regardless of the technique employed; i.e., initial seeding of the leukocytes with or without addition of phytohemagglutinin onto monolayers of human diploid cells (WI-38) or direct establishment of suspension cultures. EBV was detected in all cultures by immunofluorescence and also by electron microscopy when tested. Furthermore, the nine cultures which were examined cytogenetically revealed the C-group (#10) chromosomal marker previously found in cultured Burkitt tumor cells. These findings supported the earlier conclusion that EBV is related to, if not identical with, the causative agent of IM. Cultures of the second group commenced growth only within 30 to 60 days in five of seven attempts, depending apparently upon the early presence of WI-38 cells. These cultures also revealed the presence of EBV and, in the three examined, the C-group chromosomal marker. Leukocytes of the third group, seeded onto WI-38 monolayers, failed to become established in four attempts. The possible implications of these findings are discussed.
Physicochemical Properties of
Tipula
Iridescent Virus
Authors: Kalmakoff J. , Tremaine J. H.
Published: January 2020

The molecular weight of
Tipula
iridescent virus, based on sedimentation and diffusion coefficients, was 5.51 × 10
8
, with hydration of 0.57 g of water per g of virus. Deoxyribonucleic acid content, based on total inorganic phosphorus liberated, was 19 ± 0.2%. At 260 mμ, the virus gave an uncorrected absorbance of 18.2 cm
2
/mg of virus and a light-scattering corrected absorbance of 9.8 cm
2
/mg of virus. Amino acid analyses of the virus protein revealed a remarkable similarity to
Sericesthis
iridescent virus. The possibility is discussed that the four iridescent insect viruses reported to date bear a strain relationship.
Cation Fluxes and Permeability Changes Accompanying Bacteriophage Infection of
Escherichia coli
Authors: Silver Simon , Levine Elaine , Spielman Philip M.
Published: January 2020

Infection of
Escherichia coli
by bacteriophage T2 was accompanied by a rapid but transient increase in the rate of loss of small molecules from the bacterial cells. This transient leakage was studied with radioactive labels such as
42
K and
28
Mg. Bacteriophage-induced leakage was dependent on the ratio of phage to bacteria: the higher the multiplicity of infection, the greater the leakage. No leakage occurred at 4 C [when adsorption proceeds but injection of phage deoxyribonucleic acid (DNA) is blocked]. Leakage was caused by heavily irradiated phage as well as by normal phage; therefore, the intracellular functioning of the bacteriophage DNA was not required. This conclusion was supported by experiments which showed phage-induced leakage in the presence of chloramphenicol or sodium cyanide. Leakage could be prevented by infecting the bacteria with phage in the presence of high magnesium concentrations. Phage-induced leakage was terminated by a “sealing” reaction, after which potassium turnover by infected and uninfected cells was very similar. The sealing reaction occurred even in the presence of chloramphenicol, suggesting that the sealing is controlled by bacterial and not bacteriophage genes. We were not able to detect any effect of normal bacteriophage infection on the influx (active transport) of potassium and magnesium into the cells.
Effect of
p
H on the Protective Action of Interferon in L Cells
Authors: Hallum Jules V. , Youngner Julius S. , Arnold Nancy J.
Published: January 2020

The
p
H of the solution in which interferon was applied to L cells determined the level of resistance developed against challenge with vesicular stomatitis virus (VSV). No inhibition of challenge virus was observed when interferon was applied to cells at
p
H 6.0. At
p
H 6.5, partial inhibition of VSV replication was observed and inhibition was maximum at
p
H 7.0. Evidence was obtained that interferon interacted with L cells at
p
H 6.0, but that resistance did not develop until the cells were placed in a medium at
p
H 7.0. These effects were explained by data showing that exposure of cells to a medium at
p
H 6.0 reversibly inhibited both ribonucleic acid and protein synthesis.
Effect of Anticellular Serum on the Attachment of Enteroviruses to HeLa Cells
Authors: Axler David A. , Crowell Richard L.
Published: January 2020

Anticellular serum (ACS), in the absence of an active complement system, was shown to inhibit the attachment of poliovirus types 1 and 2, echovirus type 6, and coxsackievirus types A13, B1, and B3 to viral receptors of live HeLa cells. This is the first report to provide evidence that ACS has an inhibitory effect on the interaction between host cells and coxsackieviruses of group B. The titer of inhibitory activity of ACS varied inversely with the cell concentration used, the reaction being virtually completed after an incubation period of 30 min at 37 C. The inhibitory activity of ACS persisted for more than 4 hr at 37 C, and was shown to be reversible at
p
H 2.0, revealing that although the receptors for attaching virus were inactivated by ACS the inactivation was not permanent. These findings are consistent with the concept that antibodies in the ACS combine with and blockade viral receptors located at the cell surface. An antiserum with a specificity for inhibiting attachment of coxsackievirus B1 was obtained by dual absorption of ACS with cells saturated with coxsackievirus type B3 and chymotrypsin-treated cells. These findings offer an approach whereby the antigenic relationship of viral receptors to other constituents of the cell surface can be studied.
Process of Infection with Bacteriophage φX174
Authors: Dalgarno L. , Sinsheimer Robert L.
Published: January 2020

A group of temperature-sensitive mutants of φX174 has been isolated which can go through a single, normal one-step growth cycle at 40 C but fail to form plaques at this temperature. Such mutants fail to initiate a second cycle at 40 C; however they can gain the capacity to infect at 40 C, upon incubation for 10 min in broth at 30 C. In regaining the ability to infect, the phage appear to undergo a temperature-dependent conformational alteration. The inverse process, a reversible loss of ability to infect at 40 C, is observed when such phage produced at 30 C are incubated for 2 hr at 40 C. The defect in initiation of a second cycle of infection appears to be in the injection of viral deoxyribonucleic acid. A two-step complementation test has been used to identify the cistron coding for the affected function. Such mutants are also unusually sensitive to an irreversible thermal inactivation when incubated at 40 C.
Purification of Rabies Virus Grown in Tissue Culture
Authors: Sokol Frantisek , Kuwert Ernest , Wiktor Tadeusz J. , Hummeler Klaus , Koprowski Hilary
Published: January 2020

Extracellular rabies virus, grown in monolayer cultures of BHK21 cells in the presence of medium supplemented with bovine serum albumin, was purified by the following procedure. Virus was precipitated from infectious tissue culture fluid by zinc acetate and was resuspended in a solution of ethylenediaminetetraacetate. The suspension was filtered through a Sephadex column and was treated with ribonuclease and deoxyribonuclease. The virions were then pelleted by centrifugation at high speed and were resuspended in buffer solution. Banding of the virus by centrifugation in a sucrose density gradient was the final step in the purification procedure. Purified preparations contained bullet-shaped virus particles of variable length and little (up to 5%) contaminating host-cell material. Most of the virions were “complete”, i.e., 180 nm long, but some virus particles were shorter. The length distribution of the virions was nonrandom. Shorter virions seemed to be noninfectious and showed markedly decreased hemagglutinating activity. The complement-fixing activity and the ribonucleic acid to protein ratio of the virions were not related to the length of the virus particles. Although the properties of extracellular and intracellular viruses were similar, the procedure was not suitable for purification of intracellular rabies virus.
Use of Zonal Ultracentrifuge Systems for Biophysical Studies of Rhinoviruses
Authors: Gerin John L. , Richter Ward R. , Fenters James D. , Holper Jacob C.
Published: January 2020

This paper reports the use of zonal ultracentrifuge techniques to conduct biophysical studies of rhinoviruses grown with WI-38 cells. Good clean-out of infectivity from rhinovirus harvests was obtained with the continuous-flow B-V and B-IX rotors. Use of the B-V rotor resulted in the successful concentration of rhinovirus infectivity and antigenicity. Additional purification was achieved by the combined use of continuous-flow centrifugation and isopycnic banding procedures. Two particle sizes were found to be associated with the virus-infected cell harvests. The infectious 22-nm particle banded in density ranges of 1.38 to 1.40 g/cm
3
in CsCl and 1.26 to 1.27 g/cm
3
in potassium citrate. The 8.0 nm capsomere was composed of 2.0 nm subunits and banded with a density of protein at 1.28 g/cm
3
in CsCl. Equivalent sedimentation coefficients of 155 or 185, depending on particle density in sucrose, were calculated from rate zonal experiments by use of the B-IV zonal rotor.
Use of a restriction endonuclease in analyzing the genomes from two different strains of vaccinia virus
Authors: Gangemi J D , Sharp D G
Published: January 2020

A restriction endonuclease from Haemophilus influenzae (Hind III) specifically cleaved vaccinia DNA into 14 fragments. The molecular weights of these fragments were determined by gel electrophoresis and ranged from 0.5 x 10(6) to 30 x 10(6). Hind III digestion of the DNA from the WR and CV-1 strains of vaccinia revealed a small molecular difference in one of the resulting fragments. The average molecular weight of the entire vaccinia genome was calculated to be 125 x 10(6).
Read-Through Proteins of Group 4 RNA Bacteriophages TW19 and TW28
Authors: Aoi Takeshi , Kaesberg Paul
Published: January 2020

Group 4 phages TW19 and TW28 of
Escherichia coli
possess a “read-through” (IIb) protein, although group 2 phage GA does not. This may have implications concerning the evolution and classification of RNA phages.
Simian virus 40 mutants carrying two temperature-sensitive mutations
Authors: Chou J Y
Published: January 2020

Five temperature-sensitive mutants of simian virus 40 containing two temperature-sensitive mutations were isolated. The double mutant of the A and D complementation groups, like the D mutants, failed to complement by conventional complementation analysis and did not induce host DNA synthesis at 40 degrees C. However, under conditions that suppressed the D defect, the A:D double mutant expressed only the A defect. Thus, viral DNA replication dropped rapidly after this mutant was shifted from permissive to restrictive temperatures. The A:D double mutant failed to transfrom at the restrictive temperature when subconfluent Chinese hamster lung monolayers were used. Double mutants of A:B, A:C, and A:BC complementation groups, like their A parent, were defective in viral DNA replication, in the induction of host DNA synthesis and in the transformation of secondary Chinese hamster lung cells at the nonpermissive temperature.
Analysis of intracellular feline leukemia virus proteins. I. Identification of a 60,000-dalton precursor of feline leukemia virus p30
Authors: Okasinki G F , Velicer L F
Published: January 2020

The synthesis and release of feline leukemia virus p30 was studied using a permanently infected feline thymus tumor cell line. Disrupted cells were divided into two subcellular fractions, a cytoplasmic extract (CE) representing cellular material soluble in 0.5% NP-40 and a particulate fraction (PF) insoluble in 0.5% NP-40 but soluble in 0.2% deoxycholate and 0.5% NP-40. Intracellular feline leukemia virus p30 was isolated from infected cells by immune precipitation with antiserum to p30 and subsequent sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the precipitated proteins. Cells labeled for 3 h with [35S]methionine contained equal amounts of p30 in both the CE and the PF. p30 synthesis was estimated to be 0.8% of the total host cell protein synthesis. Immune precipitates from cell pulse labeled for 2.5 min contained a labeled 60,000-dalton polypeptide (Pp60) in the PF and a polypeptide in the CE that comigrated with feline leukemia virus p30 in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. When cells were chased after a pulse label, there was a rapid loss of Pp60 in the PF and an accumulation of p30 in the CE within 30 min followed by distribution of p30 in both the PF and the CE. Estimation of intracellular and extracellular p30 levels during a 0.5- to 24-h chase period suggested that most of the newly synthesized p30 was incorporated into extracellular virus. Typtic peptide analysis of labeled Pp60 and p30 demonstrated the presence of 13 of 15 p30 peptides within the Pp60 molecule. The tryptic peptide analysis in concert with the pulse-chase labeling data provides strong evidence that Pp60 is a precursor of p30.
Intracellular forms of adenovirus DNA. V. Viral DNA sequences in hamster cells abortively infected and transformed with human adenovirus type 12
Authors: Fanning E , Doerfler W
Published: January 2020

The persistence of viral DNA in BHK-21 cells abortively infected with human adenovirus type 12 has been investigated using reassociation kinetics. No indication of an increase in the amount of viral DNA per cell has been found. On the contrary, the amount of intracellular viral DNA sequences decreases rapidly after infection. Thus, free adenovirus type 12 DNA does not replicate in BHK-21 cells. The influence of the multiplicity of infection on the amount of persisting adenovirus type 12 DNA has also been explored. The viral DNA sequences persisting in four lines of hamster cells transformed in vitro by adenovirus type 12 at various multiplicities of infection have been quantitated and mapped by reassociation kinetics experiments using restriction endonuclease fragments of 3H-labeled adenovirus type 12 DNA. All the EcoRI restriction nuclease fragments of the adenovirus type 12 genome are represented in each of the four cell lines. Individual fragments of the viral genome are represented in multiple copies in non-equimolar amounts.