bluuebunny/crossref_metadata_2025 huggingface dataset:
Occluded and nonoccluded nuclear polyhedrosis virus grown in Trichoplusia ni: comparative neutralization comparative infectivity, and in vitro growth studies
Authors: Volkman L E , Summers M D , Hsieh C H
Published: January 2020

Nuclear polyhedrosis virus infections of lepidopteran cells often result in the production of both occluded and nonoccluded virus. The characterization of these two different forms has been the subject of several papers. We have divided the nonoccluded virus (NOV) category further into plasma membrane-budded non-occluded virus (PMB-NOV), intracellular NOV, and hemolymph-derived NOV, and have done additional studies investigating the differences between these nonoccluded forms and the alkali-liberated forms from occlusions of the nuclear polyhedrosis viruses of Autographa californica and Rachiplusa ou. The methods used to discern differences and similarities among the forms were serological, biochemical, and visual, all related to their biological acitivity. Neutralization studies revealed that alkali-liberated virus and PMB-NOV had both similar and different antigens. Antisera raised against alkali-liberated virus from occlusions neutralized the alkali-liberated form of the virus, but did not neutralize the intracellular or extracellular nonoccluded forms. Antisera raised against the TN-368-13 PMB-NOV, however, neutralized the alkali-liberated forms as well as all forms of the NOV. Adsorption of this antisera with alkali-liberated virus did not diminish the neutralization titer against the nonoccluded forms, thus confirming the antigenic differences between the alkali-liberated and nonoccluded forms of the virus. Physical-infectious particle ratio calculations indicated that the PMB-NOV of Autographa californica are about 1,900-fold more infectious than the single-nucleocapsid-per-envelope alkali-liberated particles and about 1,700-fold more infectious than the multiple-nucleocapsid-per-envelope particles, as assayed in vitro. In addition, a study of viral growth kinetics monitored concurrently with the appearance of polyhedra showed that PMB-NOV production is shut down with the onset of polyhedron formation.
Deoxyribonucleic Acid Synthesis in FV-3-infected Mammalian Cells
Authors: McAuslan B. R. , Smith W. R.
Published: January 2020

Deoxyribonucleic acid (DNA) synthesis and virus growth in frog virus 3 (FV-3)-infected mammalian cells in suspension were examined. The kinetics of thymidine incorporation into DNA was followed by fractionating infected cells. The cell fractionation procedure separated replicating viral DNA from matured virus. Incorporation of isotope into the nuclear fraction was depressed 2 to 3 hr postinfection; this inhibition did not require protein synthesis. About 3 to 4 hr postinfection, there was an increase in thymidine incorporation into both nuclear and cytoplasmic fractions. The nuclear-associating DNA had a guanine plus cytosine (GC) content of 52%; unlike host DNA it was synthesized in the presence of mitomycin C, it could be removed from nuclei by centrifugation through sucrose, and it was susceptible to nuclease digestion. This nuclear-associating DNA appeared to be a precursor of cytoplasmic DNA of infected cells. The formation of the latter DNA class could be selectively inhibited by conditions (infection at 37 C or inhibition of protein synthesis) that permit continued incorporation of thymidine into nuclear-associating DNA. The cytoplasmic DNA class also had a GC content of 52%, was resistant to nuclease degradation, and its sedimentation profile in sucrose gradients corresponded to that of infective virus. Contrary to previous reports, we found that (i) viral DNA synthesis can continue in the absence of concomitant protein synthesis, and (ii) viral DNA synthesis is not abolished at 37 C. The temperature lesion in FV-3 replication appeared to be in the packaging of DNA into the form that appears in the cytoplasmic fraction of disrupted cells.
Double-stranded Ribonucleic Acid from Cytoplasmic Polyhedrosis Virus of the Silkworm
Authors: Miura K. , Fujii I. , Sakaki T. , Fuke M. , Kawase S.
Published: January 2020

Ribonucleic acid (RNA) was extracted by phenol treatment from cytoplasmic polyhedrosis virus isolated from the midgut of infected silkworms. This RNA appears as threads when precipitated in alcohol. Two components having different sedimentation constants were observed. The molecular weight of the RNA preparation obtained by sedimentation coefficient (weight-averaged) and intrinsic viscosity was about 2 × 10
6
to 3 × 10
6
. It was one-half to one-third the size of the calculated molecular weight for an entire RNA molecule in a virion. Electron micrographs of this RNA preparation showed two peaks in the distribution of contour length, at 0.4 and 1.3 μm, which would correspond to molecular weights of 10
6
and 3 × 10
6
, respectively. The extracted RNA seemed to split into segments at a preferential breaking point. This RNA was soluble in concentrated salt solution, differing from single stranded high-molecular-weight RNA. The base composition of this RNA was complementary in the ratios of adenosine to uridine and guanosine to cytosine. It contained 43% guanosine plus cytosine. Based on its filamentous appearance by electron microscopy, typical pattern of optical rotatory dispersion and circular dichroism, sharp transition of the optical properties on heating, great hyperchromicity on degradation, nonreactivity with formaldehyde, and resistance to ribonucleases, it is concluded that this RNA is double-stranded and has regular base pairings of guanosine-cytosine and adenosine-uridine.
Fractionation of Eastern Equine Encephalitis Virus by Density Gradient Centrifugation in CsCl
Authors: Aaslestad H. G. , Hoffman E. J. , Brown Arthur
Published: January 2020

When partially purified Eastern equine encephalitis (EEE) virus was centrifuged to equilibrium in CsCl, three virus specific bands were observed. A hemagglutinin was detected at a buoyant density of 1.18 g/cm
3
. Infectious EEE virus banded in two positions; most of the virus banded at 1.20 g/cm
3
and a lesser amount banded at 1.22 to 1.23 g/cm
3
. Analysis of radioactive profiles of CsCl-fractionated EEE virus labeled with either
32
PO
4
or
3
H-uridine suggested that the hemagglutinin was stripped from the intact EEE virion. The viral origin of the hemagglutinin was verified by inhibition with specific antiserum. Attempts to differentiate between infectious EEE virus of the different buoyant densities showed that the denser particle was neither a virus contaminant nor a density mutant. No evidence was obtained to indicate that the denser particle was an immature form of EEE virus. The two infectious EEE species obtained after CsCl fractionation were indistinguishable antigenically. Furthermore, unfractionated as well as CsCl-fractionated EEE virus sedimented at about 260
S
in sucrose gradients. These results together with the results of rebanding experiments suggested that the denser EEE species (1.23 g/cm
3
) results from a salt (CsCl)-induced alteration or breakdown of the EEE virion (1.20 g/cm
3
), and that it arises as the hemagglutinin is stripped from the surface of the EEE virion.
Replication of Coliphage M-13 I. Effects on Host Cells After Synchronized Infection
Authors: Brown Lyle R. , Dowell C. E.
Published: January 2020

Techniques have been described for synchronization of bacteriophage M-13 infection of host cells. The latent period in infected cells was 10 min, and no appreciable number of intracellular phage was observed. Phage production proceeded in three phases after release of the starvation block: an initial rapid exponential rate of progeny phage release without cell lysis, a period of rate transition accompanying the resumption of host cell division, and a second, slower exponential rate of phage production which paralleled the rate of host cell division. The size of infected cells was not affected by infection, but the generation time was increased by 25%. Starved infected cells exhibited a much longer lag in attaining an exponential rate of growth upon the addition of nutrients than did an uninfected control culture.
Host Cell Participation in Small Virus Replication I. Replication of M-13 in a Strain of
Escherichia coli
with a Temperature-sensitive Lesion in Deoxyribonucleic Acid Synthesis
Authors: Primrose S. B. , Brown L. R. , Dowell C. E.
Published: January 2020

The replication of M-13 in a strain of
Escherichia coli
with a thermosensitive lesion in deoxyribonucleic acid synthesis was studied. M-13 failed to replicate at the restrictive temperature, even when the parental replicative form was allowed to form at the permissive temperature. When cells which were actively producing phage at the permissive temperature were shifted to the restrictive temperature, phage production continued. The incorporation of radioactive label into phage particles at 42 C indicated that continued single-strand synthesis was unaffected by the lesion in the host cell.
Hemagglutination by Rabies Virus
Authors: Kuwert Ernst , Wiktor Tadeusz J. , Sokol Frantisek , Koprowski Hilary
Published: January 2020

Goose erythrocytes were agglutinated by five strains of rabies virus grown in monolayer cell cultures at
p
H 6.4 and at 0 to 4 C. Hemagglutination was not affected by the cell type in which the virus was grown. Prerequisites for occurrence of hemagglutination are absence of hemagglutination inhibitors (such as those contained in bovine serum) and a relatively high virus concentration (> 10
6
plaque-forming units of virus per ml). “Soluble” hemagglutinin was not present in crude preparations of extracellular virus. Treatment of purified preparations of extracellular virus with Tween 80 and ether did not result in release of a “soluble” hemagglutinin. The hemagglutinating property of extracellular virus seemed to be conditioned by the integrity of its coat. Preparations of infectious intracellular virus exhibited about 15 times lower hemagglutinating activity than extracellular virus. This decreased hemagglutinating activity did not seem to be caused by binding of hemagglutination inhibitors to the virus particles. Rabies virus can be quantitatively adsorbed onto and eluted from erythrocytes. Erythrocytes pretreated with rabies virus retained their ability to be agglutinated by the same virus strain. The reaction with rabies virus of erythrocytes treated with the receptor-destroying enzyme or KIO
4
was the same as that of nontreated erythrocytes. The hemagglutinating component of rabies virus, therefore, does not exhibit neuraminidase activity. Treatment of extracellular virus by various agents indicated that the hemagglutinating component consists of protein or lipoprotein. Sulfhydryl groups present in the viral hemagglutinin are essential for hemagglutination.
Electron Microscopic Localization of Herpesvirus-type Particles in Marek's Disease
Authors: Ahmed Mumtaz , Schidlovsky George
Published: January 2020

Upon cultivation of chicken lymphoid tumors induced by Georgia isolate of Marek's disease, clusters of refractile rounded cells appeared consistently in the cell cultures. Intranuclear mature, immature, enveloped, and empty herpesvirus-type particles, usually associated with smaller particles, were observed in all rounded cells in the affected areas. Cytoplasmic inclusions containing mature enveloped virus particles were also seen in the rounded cells. Often fibroblasts growing in the vicinity of the cytopathic effect area contained a few herpesvirus-type particles. The original tumors prior to cultivation did not reveal any virus particles, and the virus in infected cultures was always cell-associated. Control cell cultures neither developed the rounded cells nor demonstrated the presence of any type of virus particles.
Synthesis of Soluble Ribonucleates in
Escherichia coli
Infected with Bacteriophage R17
Authors: Hudson James B. , Paranchych William
Published: January 2020

Measurements were made on the level of synthesis of soluble ribonucleates (sRNA) in
Escherichia coli
K-12 infected with the ribonucleic acid (RNA)-containing bacteriophage R17. Little or no decrease in sRNA synthesis was found to occur under conditions of infection which result in a 70 to 80% inhibition of ribosomal RNA synthesis.
Nucleotide Phosphohydrolase in Purified Vaccinia Virus
Authors: Munyon William , Paoletti Enzo , Ospina Julio , Grace James T.
Published: January 2020

Purified infectious vaccinia virus has been shown to contain an enzyme or enzymes that remove the terminal phosphate group from adenosine triphosphate (ATP), guanosine triphosphate (GTP), uridine triphosphate (UTP), and cytidine triphosphate (CTP). The
K
m
for ATP of this enzyme is 5.5 × 10
−4
m
, and the relative rates of the reaction with ATP, GTP, UTP, and CTP are 1.00, 0.34, 0.15, and 0.29, respectively. The virus enzyme does not react with any of the diphosphates. The rate of the reaction is proportional to the amount of virus added and is linear for 130 min. The virus nucleotide phosphohydrolase activity is greatly stimulated by Mg
++
and very slightly stimulated by Ca
++
. The small residual activity observed in the absence of divalent cations is completely inhibited by ethylenediaminetetraacetic acid. Neither Na
+
nor K
+
ions, nor any mixture of these, was found to stimulate the reaction significantly, and ouabain, at 10
−4
m
, inhibited the reaction by only 27%. The response of the vaccinia enzyme to mono- and divalent cations and to ouabain indicates that the vaccinia enzyme has different properties from those associated with microsomes and mitochondria.
Effect of Arginine-deficient Media on the Herpes-Type Virus Associated with Cultured Burkitt Tumor Cells
Authors: Henle Werner , Henle Gertrude
Published: January 2020

After incubation at 37 C for 2 or more days, Basal Medium Eagle (BME) supplemented with 25% fetal calf serum (FCS) was not able to support adequate growth of EB3 and other lines of Burkitt tumor cells. The medium did, however, increase, by a factor of about 10, the number of cells synthesizing herpes-type virus with which the cultures were persistently infected. Not every lot of FCS produced these effects, nor were these effects seen when BME and FCS were incubated separately for 7 days before the medium was completed. At 37 C, appropriate lots of FCS interacted with several of the amino acids present in BME; this interaction resulted in an inhibition of cellular growth, whereas interaction with arginine yielded the virus-enhancing effect. Arginine-free BME, supplemented with 25% FCS and used without prior incubation, prevented cellular replication and promoted viral infection to a similar extent as did preincubated complete medium. Replenishment of arginine reduced, but did not regularly abolish, the virus-enhancing activity of preincubated media. RPMI-1629 medium was less affected by preincubation with FCS because it contained twice the amount of arginine that BME contained. The FCS factors which act upon arginine and other amino acids are not dialyzable and are partially resistant to heating at 56 or 60 C for 30 to 60 min. Calf and horse sera appear to be devoid of these activities. The nature of these interactions, as well as the mechanism by which arginine deficiency enhanced the viral infection, remains to be ascertained.
Differentiation of Temperature Variants of Influenza A2 Viruses on the Basis of Plaque Formation
Authors: Medvedeva T. E. , Alexandrova G. I. , Smorodintsev A. A.
Published: January 2020

The ability of temperature variants of influenza A2 virus to produce plaques in chick embryo kidney tissue culture was studied at different temperatures. Definite differences in efficiency of plaque formation by cryophilic and thermophilic strains were observed at low and high temperatures. Differentiation of the temperature variants appears to reside in a number of genetic markers, designated
rct-40, rct-28
, and plaque size (
S
). Virulence of influenza A2 virus, enhanced after prolonged cultivation at high temperature, is probably related to its greater efficiency of plating at 40 C (
rct-40
+
), formation of larger plaques at optimal (36 C) and high (40 C) temperatures, and to loss of ability to form plaques at 28 C (
rct-28
−
).
Hemadsorption of Mumps Virus Examined by Light and Electron Microscopy
Authors: Duc-Nguyen Huu
Published: January 2020

The hemadsorption (HAD) reaction of chick embryo cells infected with mumps virus was studied by means of light and electron microscopy, with special reference to the plasma membrane of the infected cell. The concomitant observation of membrane-free aggregates of viral nucleocapsid in the cytoplasm and attached red blood cells on the surface of the same cell indicated that only infected cells hemadsorbed and that hemagglutinin is confined within the infected cell. The attachment of red blood cells to morphologically intact cell membrane prior to its differentiation into viral envelope suggested that the HAD phenomenon, dependent on the presence of hemagglutinin, was independent of the viral maturation process. The gap of low electron density normally separating the morphologically intact membrane of the tissue culture cell and that of the red blood cell at the binding site was replaced by newly formed surface projections in HAD involving a segment of differentiated plasma membrane.
Phospholipid Synthesis in
Escherichia coli
Infected with T4 Bacteriophages
Authors: Furrow Marjorie H. , Pizer Lewis I.
Published: January 2020

After infection of
Escherichia coli
with T4 phage, phospholipid synthesis continued but at a reduced rate. The same phospholipid components were synthesized as in uninfected cells; however, the relative rates of
32
P
i
incorporation into phosphatidylglycerol (PG) and phosphatidylethanolamine (PE) were altered. This alteration was most pronounced during the first 10 min after infection. Under these conditions, the isotope incorporated into PG equaled or exceeded that found in PG from uninfected cells. Chloramphenicol (CM) added before, but not 5 min after, infection inhibited the relative increase in PG synthesis, and CM added at different times after infection indicated that a protein synthesized between 3 and 6 min was required for this change to occur. Supplies of exogenous
l
-serine or
l
-α-glycerol-P failed to affect the relative rates of
32
P
i
incorporation into PG and PE by infected or uninfected cells. Phospholipid synthesis was somewhat higher after infection with T4rII mutants than after infection with wild-type phage. After infection with these mutants or several amber mutants, the relative synthesis of PG and PE was characteristic of T4r
+
-infected cells. The phospholipid synthesized after infection did not rapidly turn over, but infection accelerated the loss of PG synthesized prior to infection.
T-related Bacteriophages Isolated from
Shigella sonnei
Authors: Gromkova Rosa H.
Published: January 2020

The properties of three T-related phages—35, 55, and 3201—isolated from
Shigella sonnei
were studied. They were similar with respect to morphology of plaques, duration of the latent periods, lysis inhibition effect, and serological characteristics. These phages closely resembled the T-even phages. Phages 3201, 35, and 55 had the same host range and receptor specificity as phage T2.
Application of Scanning Microscopy in the Study of Virus Transmission of Aphids
Authors: de Zoeten Gustaaf A.
Published: January 2020

The scanning electron microscope was used in conjunction with the transmission electron microscope to study stylet morphology and the role of stylets of the green peach aphid in plant virus transmission. The morphology of the stylets generally agreed with earlier descriptions of these parts obtained with the transmission electron microscopy. A considerable variation seemed to exist in the extent and regularity of ridges observed in different individuals, especially among apterous adults and nymphs. Surface contamination of stylets as well as of the bristle area of the labium could be detected. The possible role of these contaminants in plant virus transmission is discussed. Working near the limit of resolution of the scanning electron microscope, visualization of two types of plant virus particles was attempted. Dipping aphid stylets in suspensions of purified virus did not lead to subsequent detection of these particles on the stylets with the scanning electron microscope. The scanning microscope is evaluated for its possibilities in the study of plant virus transmission by insects.
Biological and Serological Properties of Viral Particles from a Nonproducer Rat Neoplasm Induced by Murine Sarcoma Virus (Moloney)
Authors: Ting R. C.
Published: January 2020

The viral particles present in a nonproducer rat neoplasm induced by murine sarcoma virus (MSV) Moloney isolate, as detected by electron microscopy, were found to be biologically active on normal kidney cells of random-bred Osborne-Mendel rats. The virus is designated here as MSV (0). MSV (0) differs from other pseudotypes of MSV in its host range, antigenicity, and interference pattern.
Antiviral Activity of Polyacrylic and Polymethacrylic Acids
Authors: De Somer P. , De Clercq E. , Billiau A. , Schonne E. , Claesen M.
Published: January 2020

A marked virus-inhibiting potency is obtained in the serum after intraperitoneal injection of polyacrylic acid (PAA) and polymethacrylic acid (PMAA) in mice. Much higher antiviral levels were reached than for other related polymers including dextran sulfate, heparin, polyvinyl sulfate, pyran copolymer, polystyrene sulfonate, and macrodex. The broad antiviral action of PAA and PMAA was attributed both to a direct interference with the virus-cell interaction and the viral ribonucleic acid metabolism and to the formation of an interferon-like factor. Both polyanions differed in interferon-inducing ability: highest serum interferon titer was obtained 18 hr after the intraperitoneal injection of PAA. The mechanism of interferon production by PAA and PMAA is discussed. As described previously for Sindbis virus and endotoxin, the animals also became hyporeactive after injection of PAA.
Polyadenylate sequences of human rhinovirus and poliovirus RNA and cordycepin sensitivity of virus replication
Authors: Nair C N , Panicali D L
Published: January 2020

The polyadenylate [poly(A)] content of the genome RNA of human rhinovirus type 14 (HRV-14) is nearly twice as large as that of the genome RNA of poliovirus type 2. The poly(A) content of viral RNA was determined to be the RNase-resistant fraction of 32P-labeled viral RNA extracted from purified virions. Polyacrylamide gel electrophoresis indicated that the poly(A) sequences of HRV-14 are more heterogenous and on an average larger than those of poliovirus RNA. On the basis of susceptibility to micrococcal polynucleotide phosphorylase the rhinovirus genome terminates in poly(A). Replication of both viruses is almost totally inhibited by cordycepin at 50 mug/ml. At lower concentrations, rhinovirus replication is more sensitive to cordycepin than poliovirus replication. Addition of cordycepin (75 mug/ml) to infected culture prior to or during viral RNA replication results in more or less complete inhibition of virus-specific RNA synthesis. The results do not indicate that cordycepin sensitivity of either virus is due to preferential inhibition of viral poly(A) synthesis by this antibiotic.
Restriction and modification in Bacillus subtilis: inducibility of a DNA methylating activity in nonmodifying cells
Authors: Günthert U , Pawlek B , Stutz J , Trautner T A
Published: January 2020

The nonrestricting/nonmodifying strain Bacillus subtilis 222 (r-m-) can be induced to synthesize a DNA-modifying activity upon treatment with either mitomycin C (MC) or UV light. This is shown by the following facts. (i) Infection of MC-pretreated 222 cells with unmodified SPP1 phage yields about 3% modified phage that are resistant to restriction in B. subtilis R (r+m+). The induced modifying activity causes the production of a small fraction of fully modified phage in a minority class of MC-treated host cells. (ii) The MC-pretreated host cells contain a DNA cytosine methylating activity: both bacterial and phage DNAs have elevated levels of 5-methylcytosine. (iii) The MC-induced methylation of SPP1 DNA takes place at the recognition nucleotide sequences of restriction endonuclease R from B. subtilis R. (iv) Crude extracts of MC-pretreated 222 cells have enhanced DNA methyltransferase activities, with a substrate specificity similar to that found in modification enzymes present in (constitutively) modifying strains.
In Vitro Synthesis of Turnip Yellow Mosaic Virus Coat Protein in a Wheat Germ Cell-Free System
Authors: Benicourt C. , Haenni A. L.
Published: January 2020

Turnip Yellow Mosaic Virus RNA directs the synthesis in vitro of its coat protein in a wheat germ cell-free extract. Optimum conditions for synthesis have been defined, and the effect of spermine on specifically enhancing coat protein formation has been examined. Identity between the in vitro synthesized coat protein and authentic coat protein of Turnip Yellow Mosaic Virus was established by analysis on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, peptide mapping, and immunoprecipitation.
Genetic Evidence that
Bacillus
Bacteriophage φ105 Integrates by Insertion
Authors: Dean D. H. , Arnaud M. , Halvorson H. O.
Published: January 2020

Genetic analysis by PBS1 transduction has demonstrated that bacterial markers spanning the φ105 attachment site are spread upon integration, accounting for insertion of one or more φ105 genomes.
Consequences of herpes simplex virus type 2 and human cell interaction at supraoptimal temperatures
Authors: Marcon M J , Kucera L S
Published: January 2020

The consequences of herpes simplex virus type 2 (HSV-2) and human embryonic fibroblast cell interaction at different temperatures (37, 40, and 42 degrees C) were investigated. Incubation at 37 or 40 degrees C was permissive for HSV-2 inhibition of host DNA synthesis, induction of virus-specific DNA replication, and infectious virus production. The amount of [methyl-3H]thymidine incorporated into viral DNA and the final yield of new infectious virus were significantly reduced at 40 degrees C compared to 37 degrees C. At 42 degrees C, detectable virus-specific DNA synthesis was totally blocked. Maximum stimulation of host cell DNA synthesis at 42 degrees C was measured after a multiplicity of infection of 0.5 to 1.0 PFU/cell. By autoradiography, data indicated that HSV-2 stimulates host cell chromosomal DNA synthesis. Stimulation of thymidine kinase activity with thermostability properties in common with a virus enzyme was detected during the first 24 h of infection at 42 degrees C, after 24 h the enhanced thymidine kinase activity had properties in common with host cell isozymes. The data obtained during this investigation indicated that stimulation of host cell DNA synthesis does not require viral DNA synthesis.
Simian virus 40-permissive cell interactions: selection and characterization of spontaneously arising monkey cells that are resistant to simian virus 40 infection
Authors: Wilson J H , DePamphilis M , Berg P
Published: January 2020

A fraction of permissive cells survive simian virus 40 (SV40) infection. The frequency of such surviving cells depends only upon the concentration of infecting virus, both parental and progeny, to which the cells are exposed during the course of selection. Surviving clones, which can be freed of virus by cloning in the presence of SV40 antiserum, are indistinguishable from parental cells in their growth of characteristics and display no SV40 antigen; thus they are not transformed. Most surviving clones are less than 10% as susceptible as parental cells to SV40 infection; 5 to 10% are less than 1% as susceptible. None of these SV40-resistant clones is absolutely resistant to SV40 infection. Analysis of 16 independently arising resistant clones indicates that they all block SV40 infection at an early stage after adsorption and eclipse but before full uncoating. Viral mutants have been isolated that partially overcome the block to infection in these cells; these host range viruses plaque on resistant lines fivefold more efficiently than wild-type SV40 and have a characteristic plaque morphology. Fluctuation analysis indicates that resistant cells arise spontaneously during the growth of normally susceptible permissive cells. Thus, SV40-resistant cells are selected for, not induced by, SV40 infection.
Bacterial rep- mutations that block development of small DNA bacteriophages late in infection
Authors: Tessman E S , Peterson P K
Published: January 2020

Several related mutants of Escherichia coli C have been isolated that block the growth of the small icosahedral DNA phages phiX174 and S13 late in infection. Phage G6 is also blocked, at a stage not yet known. Growth of the filamentous phage M13, though not blocked, is affected in these strains. These host mutations co-transduce with ilv at high frequency, as do rep- mutations. However, the new mutants, designated groL-, differ from previously studied rep- mutants in that they permit synthesis of progeny replicative-form DNA. The groL- mutants are blocked in synthesis of stable single-stranded DNA of phiX174 and related phages. They are gro+ for P2. Evidence that groL- mutations and rep- mutations are in the same gene is presented. Spontaneous mutants (ogr) of phiX174, S13, and the G phages can grow on groL- strains. The ogr mutations are located in the phage's major capsid gene, F, as determined by complementation tests. There are numerous sites for mutation to ogr. Some mutations in genes A and F interfere with the ogr property when combined with an ogr mutation on the same genome. The ogr mutations are cis acting in a groL- cell; i.e., an ogr mutant gives very poor rescue of a non-ogr mutant. The wild-type form of each G phage appears to be naturally in the ogr mutant state for one or more groL- strains. It is suggested that a complex between F and rep proteins is involved in phage maturation. The A protein appears to interact with this complex.
Replication of semliki forest virus: polyadenylate in plus-strand RNA and polyuridylate in minus-strand RNA
Authors: Sawicki D L , Gomatos P J
Published: January 2020

The 42S RNA from Semliki Forest virus contains a polyadenylate [poly(A)] sequence that is 80 to 90 residues long and is the 3'-terminus of the virion RNA. A poly(A) sequence of the same length was found in the plus strand of the replicative forms (RFs) and replicative intermediates (RIs) isolated 2 h after infection. In addition, both RFs and RIs contained a polyuridylate [poly(U)] sequence. No poly(U) was found in virion RNA, and thus the poly(U) sequence is in minus-strand RNA. The poly(U) from RFs was on the average 60 residues long, whereas that isolated from the RIs was 80 residues long. Poly(U) sequences isolated from RFs and RIs by digestion with RNase T1 contained 5'-phosphorylated pUp and ppUp residues, indicating that the poly(U) sequence was the 5'-terminus of the minus-strand RNA. The poly(U) sequence in RFs or RIs was free to bind to poly(A)-Sepharose only after denaturation of the RNAs, indicating that the poly(U) was hydrogen bonded to the poly(A) at the 3'-terminus of the plus-strand RNA in these molecules. When treated with 0.02 mug of RNase A per ml, both RFs and RIs yielded the same distribution of the three cores, RFI, RFII, and RFIII. The minus-strand RNA of both RFI and RFIII contained a poly(U) sequence. That from RFII did not. It is known that RFI is the double-stranded form of the 42S plus-strand RNA and that RFIII is the experimetnally derived double-stranded form of 26S mRNA. The poly(A) sequences in each are most likely transcribed directly from the poly(U) at the 5'-end of the 42S minus-strand RNA. The 26S mRNA thus represents the nucleotide sequence in that one-third of the 42S plus-strand RNA that includes its 3'-terminus.
Respiratory syncytial virus ts mutants and nuclear immunofluorescence
Authors: Faulkner G P , Shirodaria P V , Follett E A , Pringle C R
Published: January 2020

A replicated sector-plating procedure was used to isolate 35 induced temperature-sensitive (ts) mutants and one spontaneous ts mutant from a wild-type stock of respiratory syncytial (RS) virus cloned from recent clinical material. Seven of these mutants were ts for plaque formation at 37 degrees C as well as at the restrictive temperature of 39 degrees C. The wild-type strain did not differ markedly from standard laboratory strains of RS virus. It was dependent on exogenous arginine (84 mug/ml) for optimal growth, and was not significantly inhibited by mitomycin C (10 mug/ml). It was sensitive to actinomycin D (2.5 mug/ml) during the early part of the growth phase. A characteristic focal cytopathic effect was obtained in BS-C-1 cells. Staining of infected monolayers by an indirect immunofluorescence procedure revealed a profusion of filamentous processes extending from the plasma membrane, and a similar modification of the surface of infected cells could be visualized by scanning electron microscopy. Filament production was inhibited when certain ts mutants were incubated at 39 degrees C, confirming the virus-specific nature of the phenomenon. Thirty-four of the mutants were classified into three groups by immunofluorescence. Complementation was observed in mixed infection with a single mutant from each group. Nuclear, as well as cytoplasmic, immunofluorescence was detected in RS virus-infected cells using a high-titer bovine anti-bovine RS virus serum. Visualization of nuclear antigen was dependent on the inhibition of cytoplasmic fluorescence obtained when ts mutants in groups I and III were incubated at restrictive temperature.
Effects of temperature and antibody on the cyclid growth of vesicular stomatitis virus
Authors: Sinarachatanant P , Huang A S
Published: January 2020

To see the effects of temperature on the interrelated cyclic production of standard and defective interfering (DI) particles of vesicular stomatitis virus, a temperature-sensitive (ts) G114 mutant was passaged successively at different temperatures and the production of the two types of viral particles as well as the ability of Chinese hamster ovary cells to survive each passage was continuously monitored. When the temperature was nonpermissive for standard virus, the synthesis of both standard and defective interfering particles was inhibited. When revertants appeared in the population, their ability to take over the infection depended on the permissiveness of the temperature for the temperature-sensitive mutant. At permissive temperatures periodic inhibition of both types of standard viruses was maintained by the production of defective interfering particles. Reverents did not become a majority of the population due to this periodic inhibition. When the conditions were nonpermissive for the mutant, revertants became the major standard virus in the population within a few passages. These findings can be understood if conditions of high and low multiplicities are dissected out together with a thorough understanding of the individual properties of each of the viral particles and of the result of interactions between them. In the presence of antiserum which neutralized only 90% of the viral particles, cyclic production of standard virus occurred, with a decline in the total amount of virus produced after each cycle. Therefore, in the presence of limiting concentrations of antiserum, the virus appeared to be able to establish a persistent cyclic growth pattern.
Common structural antigen of papovaviruses of the simian virus 40-polyoma subgroup
Authors: Shah K V , Ozer H L , Ghazey H N , Kelly T J
Published: January 2020

An antigenic determinant common to the major capsid polypeptide (VP1) of simian virus 40 (SV40) and polyoma virus is described. Antisera prepared against intact viral particles reacted only with cells infected with the homologous virus by immunofluorescence tests (IF). However, antisera prepared against disrupted SV40 particles reacted in IF with both polyoma- and SV40-infected permissive cells. The cross-reaction with polyoma was localized to VP1 by the following evidence. (i) The IF cross-reaction was inhibited by preincubation of the antiserum with purified SV40 VP1; (ii) purified radiolabeled polyoma VP1 was precipitated by the cross-reactive serum, and this reaction was inhibited by unlabeled SV40 VP1; (iii) other antisera prepared against purified SV40 VP1 or polyoma VP1 reacted in IF with both SV40- and polyma-infected permissive cells. These cross-reacting antisera also reacted in IF with permissive cells infected with BK virus, rabbit kidney vacuolating virus, and the stumptailed macaque virus, suggesting that all members of the polyoma-SV40 subgroup share a common antigenic determinant located in their major capsid polypeptides.
In vitro translation with adenovirus polyribosomes
Authors: Persson H , Oberg B , Philipson L
Published: January 2020

Polyribosomes isolated from adenovirus type 2 (Ad2)-infected HeLa cells late in productive infection can be used for translation in cell-free systems. At least eight viral polypeptides are synthesized, including the precursors to virion polypeptides VI and VII. Separation of polyribosomes by zonal rate centrifugation followed by translation in a cell-free system reveals a correlation between the sizes of the polyribosomes and the polypeptides synthesized. The cell-free extracts incorporate amino acid linearly for only 10 min and show little or no capacity to reinitiate protein synthesis. The elongation efficiency measured as the number of amino acids incorporated per ribosome in 20 min is low, ranging from 10 to 100. The maximum chain elongation rate is estimated to be 10 to 20 amino acids per min. The limited elongation has been used to assess the relative concentration of mRNA's engaged in translation.
Molecular weight of DNA from four entomopoxviruses determined by electron microscopy
Authors: Langridge W H , Roberts D W
Published: January 2020

DNA was isolated from entomopoxviruses infected Amsacta moorei and Euxoa auxiliaris (Lepidoptera), Goeldichironomus holoprasinus (Diptera), and Othnonius batesi (Coleoptera) and compared with vertebrate virus DNA (vaccinia). After incubation in Pronase, sodium lauryl sulfate, and deoxycholate, poxvirus preparations shadowed with platinum and palladium revealed subcore particles 45 to 60 nm in diameter. Continued incubation in Pronase resulted in the gradual release of DNA from the particles. Metal-shadowed DNA molecules were photographed in the electron microscope and measured, and the average molecular weights were calculated. Lepidopteran poxvirus DNA (135 X 10(6)) was approximately equal to vaccinia DNA (131.7 X 10(6)) in molecular weight. The molecular weight of dipteran and coleopteran poxvirus DNA (200 X 10(6) to 251 X 10(6)) was approximately 50% greater than vaccinia DNA. Based on the concentration of DNA and protein per virion, Amsacta entomopoxvirus contained 5.7 to 7.7% DNA.
Viral protein synthesis in Friend erythroleukemia cell lines
Authors: Racevskis J , Koch G
Published: January 2020

Viral protein synthesis was studied in two Friend virus-induced erythroleukemia cell lines (Ostertag cell lines FSD1-F4 and B8) by the technique of immuno-precipitation with monospecific antisera to the major envelope glycoprotein gp70 and major core protein p30. One of the cell lines (F4) releases active Friend virus complex to the growth medium, where release of virus from the other cell line (B8) is barely or nondetectable. It was found that in the nonproducer cell line B8, a large-molecular-weight protein of about 65,000 containing p30 antigenic determinants is synthesized, yet no p30 is produced upon prolonged incubation and chase, suggesting that this might be the actual lesion that prevents mature virus production by these cells. In both cell lines, the predominant protein species that is immunoprecipitated with monospecific anti-gp70 serum is a protein of 55,000 to 60,000 daltons that is labeled with glucosamine to a much lesser extent that gp70 and appears to become heterogeneous with time. Large amounts of gp70 can be detected in the cell-free medium, but none of the unstable species of 55,00 to 60,000 molecular weight.
Presence of deletion molecules in human wart virus DNA
Authors: Yoshike K , Defendi V
Published: January 2020

Deletion mutants of human wart virus were found to occur occasionally in the virus population transmitted in vivo, although the majority of virion DNA molecules were homogeneous in length and base sequence. Human wart virus DNA was 1.48 times as long as nondefective simian virus 40 DNA.
Influence of defective virion core proteins on RNA maturation with an avian sarcoma virus
Authors: Harms E , Rodhe W , Friis R R , Bauer H
Published: January 2020

The RNA of the avian sarcoma virus B77 temperature-sensitive mutant LA334 was investigated using electrophoretic analysis. The RNA from mutant virus grown at the nonpermissive temperature (42degrees C) showed a heterogeneous peak between 80 and 125S, and another at about 35S. The RNA of the mutant virus grown at the permissive temperature (35 degrees C) behaved like wild-type B77 virus RNA, exhibiting a major peak at 70S. The homology between the various RNA fractions and virus-specific DNA probe was determined, indicating that mutant virus grown at the nonpermissive temperature contains relatively large amounts of nonviral-specific RNA.
Use of defective interfering particle RNA probes in the determination of the order of in vitro transcription of vesicular stomatitis virus genes
Authors: Reddy D V , Schnitzlein W M , Reichmann M E
Published: January 2020

Annealing of various defective interfering particle RNAs of vesicular stomatitis virus to early in vitro viral transcription products has shown that transcription is sequential, with 13S to 18S mRNA's being produced first. Based on this finding, the 30S mRNA cistron is located at the 5' end of the viral genome.
Synthesis of Epstein-Barr virus DNA in vitro: effects of phosphonoacetic acid, N-ethylmaleimide, and ATP
Authors: Seebeck T , Shaw J E , Pagano J S
Published: January 2020

Nuclei from superinfected Raji cells synthesized Epstein-Barr Virus (EBV) DNA in vitro in the absence of cell DNA synthesis. The synthesis of EBV DNA in vitro was inhibited by phosphonoacetic acid and N-ethylmaleimide, and maximum synthesis was achieved in the absence of an ATP-regenerating system. Nuclei from mock-infected cells required an ATP-regenerating system for maximum DNA synthesis.
DNA synthesized in the hepatitis B Dane particle DNA polymerase reaction
Authors: Lutwick L I , Robinson W S
Published: January 2020

Radioactive DNA was prepared in extensive (4 h) Dane particle DNA polymerase reactions. In different experiments the amount of new DNA, determined by the amount of nucleotide incorporation into an acid-insoluble form, was between 29 and 45% of the total circular DNA isolated from Dane particle preparations after the reaction. DNA reassociation kinetics were used to determine the complexity of the newly synthesized DNA. In different experiments COt1/2 values, corresponding to between 625 and 1,250 nucleotide pairs, were obtained for the radioactive Dane particle DNA. These results suggest that a unique region (or regions), corresponsing to approximately one-fourth to one-half of the circular Dane particle DNA template, was copied one time during the reaction. DNA and RNA extracted from hepatitis B virus-infected liver but not from uninfected liver accelerated the rate of reassociation of radioactive DNA from Dane particles. These Dane particle DNA base sequences were found in alkali-stable, rapidly sedimenting DNA from infected liver as well as in DNA sedimenting at a rate similar to the DNA extracted from Dane particles. These findings are consistent with Dane particle DNA being hepatitis B virus DNA that is integrated into high-molecular-weight cellular DNA and transcribed into RNA in infected liver.
Assembly of viral membranes. I. Association of vesicular stomatitis virus membrane proteins and membranes in a cell-free system
Authors: Morrison T G , McQuain C
Published: January 2020

We report here an in vitro system designed to study the interactions of vesicular stomatitis virus (VSV) proteins with cellular membranes. We have synthesized the VSV nucleocapsid (N) protein, nonstructural (NS) protein, glycoprotein (G protein), and membrane (M) protein in a wheat germ, cell-free, protein-synthesizing system directed by VSV 12 to 18S RNA. When incubated at low salt concentrations with purified cytoplasmic membranes derived from Chinese hamster ovary cells, the VSV M andG proteins bind to membranes, whereas the VSV N and NS proteins do not. The VSV M protein binds to membranes in low or high divalent cation concentrations, whereas binding of significant amounts of G protein requires at least 5 mM magnesium acetate concentrations.
Bacillus subtilis DNA polymerase III is required for the replication of DNA of bacteriophages SPP-1 and phi 105
Authors: Rowley S D , Brown N C
Published: January 2020

The replication of the Bacillus subtilis bacteriophages SPP-1 and phi 105 is sensitive to 6-(p-hydroxyphenylazo)-uracil (HPUra), a selective inhibitor of replicative DNA synthesis of B. subtilis which acts specifically at the levels of a replication-specific polymerase, DNA polymerase III (pol III). The origin of the HPUra-sensitive polymerase required for phage replication was examined by comparison of the drug sensitivity of phage development in a normosensitive host with that in a host carrying azp-12, a polC mutation that specifies production of an HPUra-resistant pol III. azp-12 specified HPUra-resistant phage host pol III. The host polIII requirement for SPP-1 replication also was confirmed by the demonstration that phage development was temperature sensitive in a host mutant carrying the polC mutation mut-1 (ts). Examination of the pol III activity of crude and purified cell-free preparations derived from phage-infected cells did not indicate any detectable changes in the specific activity, purification behavior, or drug sensitivity of the enzyme.
Infectious linear DNA sequences replicating in simian virus 40-infected cells
Authors: Gruss P , Sauer G
Published: January 2020

A new class of linear duplex DNA structures that contain simian virus 40 (SV40) DNA sequences and that are replicated during productive infection of cells with SV40 is described. These structures comprise up to 35% of the radioactively labeled DNA molecules that can be isolated by selective extraction. These molecules represent a unique size class corresponding to the length of an open SV40 DNA molecule (FO III), and they contain a heterogeneous population of DNA sequences either of host or of viral origin, as shown by restriction endonuclease analysis and nucleic acid hybridization. Part of the FO III DNA molecules contain viral-host DNA sequences covalently linked with each other. They start to replicate with the onset of SV40 superhelix replication 1 day after infection. Their rate of synthesis is most pronounced 3 days after infection when superhelix replication is already declining. Furthermore, they cannot be chased into other structures. At least a fraction of these molecules is infectious when administered together with DEAE-dextran to permissive cells. After intracellular circularization, superhelical DNA FO I with an aberrant cleavage pattern accumulates. In addition, tumor and viral capsid antigen are induced, and infectious viral progeny is obtained. Infection of cells with purified SV40 FO I DNA does not result in FO III DNA molecules in the infected cells or in the viral progeny. It is suggested, therefore, that these FO III DNA molecules are perpetuated within SV40 virus pools by encapsidation into pseudovirions.