bluuebunny/crossref_metadata_2025 huggingface dataset:
Transcription of simian virus 40. V. Regulattion of simian virus 40 gene expression
Authors: Laub O , Aloni Y
Published: January 2020

RNA "exhaustion type" hybridization was used to measure the complementarity of nuclear and cytoplasmic viral RNA to the early (E) and late (L) simian virus 40 (SV40) DNA strands. This type of hybridization measures the amount of labeled RNA complementary to each of the two DNA strands, rather than the fraction of each SV40 DNA strand that is homologous to SV40 RNA. At 48 h after infection, about 5% of the nuclear newly synthesized viral RNA was complementary to the E-strand (- strand) and 95% was complementary to the L-strand (+ strand). This proportion was independent of the labeling time, indicating similar accumulation of the E- and L-RNA transcripts in the nucleus. The nuclear E- and L-viral RNA transcripts sedimented in a similar manner on sucrose gradients. Of the cytoplasmic viral RNA only about 1% was complementary to the E-strand, these molecules sedimenting at 19S, whereas 99% were complementary to the L-strand and sedimented at 19S and 16S. The abundance of E-RNA transcripts in nuclei of cells infected with serially passaged virus was about four times higher than that in nuclei of cells infected with plaque-purified virus; however, the size and proportion of the corresponding cytoplasmic E- and L-RNA transcripts was independent of the type of virus used to infect the cells. According to these results at least two control mechanisms regulate viral gene expression in productively infected cells, one operates at the trnascriptional level and the second at the post-transcriptional level.
Host influence on the activity of genes c1 and c3 in regulating the decision between lysis and lysogency in bacteriophage P22
Authors: Tokuno S I , Gough M
Published: January 2020

A Polymyxin B-sensitive mutant of Salmonella typhimurium (Pox-1) channels all infecting wild-type P22 toward lysogenization. The efficiency of this channeling is sufficiently high that P22c+ (wild type) cannot form plaques on Pox-1; phage mutants defective in repressor synthesis (P22c1, c2, c3) or refractory toward repressor (P22vir B) can form plaques. The lytic growth of all phages which have a functional c1 gene is retarded in Pox-1; this retardation is seen even in phages which cannot make repressor. We present experiments which are consistent with the explanation that the retardation is an exaggeration of a normal regulatory event. In a wild-type host, P22 genes c1 and c3 products, host RNA polymerase, and other host factors (?) interact at a promotor site (c27) IN THE PHAGE DNA. This interaction promotes repressor synthesis and represses transcription of lytic genes. In the mutant Pox-1, a host product involved in viral DNA synthesis and transcription is altered. The altered host product results in stronger retardation of lytic gene transcription. The importance of this interaction in the decision between lysis and lysogeny is discussed. The mutant Pox-1 alters the expression or activity of another phage gene. Gene c3 product is absolutely required for lysogenization in this host, although it is not so required in wild-type S. typhimurium.
In vitro transcription of DNA from the 70S RNA of Rous sarcoma virus: identification and characterization of various size classes of DNA transcripts
Authors: Collett M S , Faras A J
Published: January 2020

DNA transcripts, ranging from 1,500 to 4,500 nucleotides in length, can be identified in the DNA product synthesized in vitro by the Rous sarcoma virus-associated RNA-directed DNA polymerase. Although these DNA transcripts are considerably larger than the size classes of the DNA product previously reported, they only represent a minor proportion (less than 5%) of the total DNA synthesized in standard reaction mixtures containing rate-limiting concentration of one of the four deoxynucleoside triphosphates. However, the proportion of these larger transcripts relative to the total DNA product increases substantially when the enzymatic synthesis of DNA is performed in the presence of equimolar concentrations of deoxynucleoside triphosphate precursors. Both rate-zonal sedimentation in alkaline sucrose and nucleic acid hybridization techniques have confirmed the length and genetic complexity of these larger DNA transcripts. The identification of large DNA chains in the DNA product synthesized in vitro by the avian oncornavirus RNA-directed DNA polymerase provides an explanation for the paradox that exists between the limited number of primer sites per 70S RNA genome, the small size of the bulk of the DNA product, and the extent of the Rous sarcoma virus genome represented by the DNA product.
N-terminal amino acid sequences in the major capsid proteins of foot-and-mouth disease virus types A, O, and C
Authors: Matheka H D , Bachrach H L
Published: January 2020

Sequences of amino acids at the N-termini of virus proteins VP1, VP2, and VP3 were determined for foot-and-mouth disease virus types A12 strain 119, O1Brugge and C3Resende. In the polyacrylamide gel electrophoresis system used to purify the proteins, VP3 migrated faster than VP1 or VP2; and in the virion, VP3 could be cleaved by trypsin into VP3a and VP3b. The N-terminal amino acids for each of the virus types were glycine in VP1, aspartic acid in VP2, and threonine in VP3. No divergences in sequence across the virus types were indicated until at least the fourth position in VP1, and the third in VP3. For virus types A12, O1 and C3, the sequences were, respectively: for VP1 (Gly-ile-phe,pro,val---), (Gly,ile,phe---) and Gly-ile-phe,ala---); for VP2 (Asp,X,met---), (Asp---) and Asp-leu---); and for VP3 (Thr-thr-ala-thr---), (Thr-thr-ser---) and (Thr-thr---). Unresolved mixtures of VP3a and VP3b, from either A12 or O1 viruses, appeared to have the N-terminal amino acids threonine, which is presumed to be the same threonine as in uncleaved VP3 and serine, which is generated by the tryptic cleavage.
Proteins specified by herpes simplex virus. XIII. Glycosylation of viral polypeptides
Authors: Honess R W , Roizman B
Published: January 2020

In the course of herpes simplex virus 1 (HSV-1) replication in human epidermoid carcinoma no. 2 cells, the synthesis and glycosylation of host cell proteins ceases and is replaced by the synthesis and glycosylation of virus-specified polypeptides. Analyses of the synthesis of viral glycoproteins show that the glycosylation of viral polypeptides occurs late in the virus growth cycle and that certain of the precursors to major vital glycoproteins are members of the gamma group of polypeptides, i.e., polypeptides synthesized at increasing rates until 12 to 15 h postinfection. Viral glycoproteins are formed by stepwise additions of heterosaccharide chains to completed precursor polypeptides. The precursor and the highly glycosylated product are separable by gel electrophoresis and are localized in different fractions of infected cells. Within 15 min of their synthesis, precursor polypeptides acquire heterosaccharide chains of about 2,000 molecular weight, which contain glucosamine but little or nor fucose or sialic acid. Both precursor and product of this first stage of glycosylation are absent or present in low concentrations in the surface membranes of the infected cell and in the virion. The partially glycosylated product is then conjugated further in a slow, discontinuous process to form the mature glycoprotein of the virion and plasma membrane. These mature products bear large heterosaccharide units with molecular weights greater than 4,000 to 5,000; these contain fucose and sialic acid as well as glucosamine. Heterosaccharide chains from infected and uninfected cells are distributed among discrete size classes and the smallest chains consist of multiple saccharide residues.
Comparison of the virion proteins specified by herpes simplex virus types 1 and 2
Authors: Cassai E N , Sarmiento M , Spear P G
Published: January 2020

Purified herpes simplex virus type 2 (HSV-2) virions were found to contain approximately the same number of polypeptides as HSV type 1 (HSV-1) virions. Comparisons of the structural proteins specified by five independent HSV-2 isolates revealed some minor differences in their electrophoretic profiles on sodium dodecyl sulfate-acrylamide gels; certain invariant features of the electrophoretic profiles, however, allowed clear differentiation between all the HSV-2 isolates and HSV-1.
Selective suppression of cellular protein synthesis in BHK-21 cells infected with rabies virus
Authors: Madore H P , England J M
Published: January 2020

Under hypertonic conditions, cellular protein synthesis is selectively suppressed in rabies virus-infected cells. The resistance of viral polypeptide synthesis to hypertonic conditions provides a means to study intracellular viral protein synthesis and may represent a property common to translation of many viruses.
Characterization of the mRNA of influenza virus
Authors: Glass S E , McGeoch D , Barry R D
Published: January 2020

The kinetics of the appearance of influenza mRNA, the distribution of mRNA between free and membrane-associated polyribosomes, its poly(A) content, and the extent to which the genome was transcribed into mRNA early in infection were determined. Polyribosomes were prepared from influenza virus-infected cells labeled for 30-min periods at various times after infection with [3H]uridine. Most of the 3H-labeled RNA extracted from these polyribosomes sedimented as a heterogeneous 8S to 20S peak in sucrose gradients, and it was largely complementary to virion RNA. By the following criteria, the complementary RNA had properties normally ascribed to mRNA: (i) it labeled rapidly with [3H]uridine; (ii) after glutaraldelyde treatment, it banded with polyribosomes in CsCl density gradients; and (iii) it contained poly(A). In chick cells at 37 C, virus mRNA was first detectable at 45 min postinfection and reached its maximal rate of appearance at 2 to 2.5 h postinfection. The free and membrane-bound polyribosomes of infected cells were separated and were found to contain the same classes of mRNA. There was no absolute segregation of mRNA sequences into either polyribosome class although each probably contained distinct ratios of the different mRNA's. From 45 min postinfection onwards, both membrane-bound and free polysomal poly(A)-containing RNA contained sequences complementary to at least 80% of the genome RNA, whereas poly(A)-minus RNA contained sequences complementary to 90 to 100% of the genome. There was no evidence for the temporal control of transcription of influenza mRNA. At 31 C, when virus development was slowed relative to 37 C,complementary RNA first appeared at 1 h postinfection. At this time, total polysomal RNA contained sequences complementary to the whole genome.
Transcription of 70S RNA by DNA polymerases from mammalian RNA viruses
Authors: Abrell J W , Reitz M S , Gallo R C
Published: January 2020

DNA polymerases purified by the same procedure from four mammalian RNA viruses, simian sarcoma virus type 1, gibbon ape lymphoma virus, Mason-Pfizer monkey virus, and Rauscher murine leukemia virus are capable of transcribing heteropolymeric regions of viral 70S RNA without any other primer. In this reconstituted system the enzymes from simian sarcoma virus type 1, Mason-Pfizer monkey virus, and Rauscher murine leukemia virus transcribe viral 70S RNA almost as efficiently as the DNA polymerase from the avian myeloblastosis virus, but gibbon ape lymphoma virus DNA polymerase is approximately three-to fivefold less efficient. Although there is a substantial difference among the sizes of these DNA polymerases (160,000 daltons for the avian myeloblastosis virus enzyme, 110,000 daltons for the Mason-Pfizer monkey virus enzyme, and 70,000 daltons for the mammalian type C viral polymerases), the ability to transcribe viral 70S RNA is a characteristic common to these enzymes.
Replication and persistence of measles virus in defined subpopulations of human leukocytes
Authors: Joseph B S , Lampert P W , Oldstone M B
Published: January 2020

Replication of Edmonston strain measles virus was studied in several human lymphoblast lines, as well as in defined subpopulations of circulating human leukocytes. It was found that measles virus can productively infect T cells, B cells, and monocytes from human blood. These conclusions were derived from infectious center studies on segregated cell populations, as well as from ultrastructural analyses on cells labeled with specific markers. In contrast, mature polymorphonuclear cells failed to synthesize measles virus nucleocapsids even after infection at a relatively high multiplicity of infection. Measles virus replicated more efficiently in lymphocytes stimulated with mitogens than in unstimulated cells. However, both phytohemagglutinin and pokeweed mitogen had a negligible stimulatory effect on viral synthesis in purified populations of monocytes. In all instances the efficiency of measles virus replication by monocytes was appreciably less than that of mitogenically stimulated lymphocytes or of continuously culture lymphoblasts. Under standard conditions of infection, all of the surveyed lymphoblast lines produced equivalent amounts of measles virus regardless of the major histocompatibility (HL-A) haplotype. Hence, no evidence was found that the HL-A3,7 haplotype conferred either an advantage or disadvantage with respect to measles virus synthesis in an immunologically neutral environment. A persistent infection with measles virus could be established in both T and B lymphoblasts. The release of infectious virus from such persistently infected cells was stable over a period of several weeks and was approximately 100-fold less than peak viral titers obtained in each respective line after acute infection.
Block to multiplication of adenovirus serotype 2 in monkey cells
Authors: Klessig D F , Anderson C W
Published: January 2020

The block to adenovirus 2 (Ad2) multiplication in monkey cells can be overcome by coinfection with simian virus 40 (SV40). To identify this block we have compared the synthesis of Ad2 proteins in monkey cells infected with Ad2 alone (unenhanced) or with Ad2 plus SV40 (enhanced). Synthesis of viral proteins in enhanced cells was virtually identical to that found for permissive infection of human cells by Ad2 alone. In contrast, the unenhanced cells were strikingly deficient in the production of the IV (fiber) and 11.5K proteins whereas the synthesis of 100K and IVa2 was normal. Synthesis of a number of other proteins such as II, V, and P-VII was partially reduced. A similar specific reduction in synthesis of these proteins was found when their messages were assayed by cell-free translation. This result suggests that the block to Ad2 protein synthesis is at the RNA level rather than with the translational machinery of monkey cells. Analysis of the complexity and the concentration of Ak2-specific RNAs, using hybridization of restriction endonuclease fragments of the Ad2 genome to increasing concentrations of RNA, shows that although all species of late Ad2 mRNA are present, the concentration of several species is reduced sevenfold or more in unenhanced monkey cells as compared with enhanced cells. These species come from regions of the genome known to encode the deficient proteins. A model for the failure of adenovirus to multiply in monkey cells, based on abnormal processing of specific adenovirus messages, is presented.
Identification of P48 and P54 as components of bacteriophage T4 baseplates
Authors: Berget P B , Warner H R
Published: January 2020

The involvement of two bacteriophage T4 gene products in the initiation of T4 tail tube and sheath polymerization on mature baseplates has been studied by radioautography of acrylamide gels of various partially completed tail structures. The products of genes 48 and 54 (P48[the nomenclature P48 refers to the protein product of bacteriophage T4 gene 48] and P54), which are known to be required for the synthesis of mature baseplates, have been shown to be structural components of the baseplate. These gene products have molecular weights of 42,000 and 33,000, respectively. The addition of P54 to the baseplate not only permits the polymerization of the core protein, P19, onto the baseplate, but also caused the disappearance of a polypeptide of molecular weight about 15,000 from the supernatant fraction of infected cells. Another gene product, P27, has been identified in the crude extracts of infected cells. This gene product, which is required for the synthesis of baseplate structures, has the same mobility as one of the unidentified structural polypeptides of the baseplate and is therefore probably also a baseplate component.
Reactivity of Avian RNA Tumor Viruses with Lectins
Authors: Ishizaki Ryotaro , Bolognesi Dani P.
Published: January 2020

The infectivity of avian RNA tumor viruses was inactivated to varying degrees by treatment with either concanavalin A (Con A) or phytohemagglutinin but not by treatment with wheat germ agglutinin. In general, leukosis viruses reacted preferentially with Con A, whereas sarcoma viruses showed more affinity for phytohemagglutinin. In a more extensive study with subgroup A of Prague Rous sarcoma virus (PR-A), the effect of inactivation by Con A could be specifically prevented by the addition of α-methyl-
d
-mannoside, α-methyl-
d
-glucoside, and
N
-acetyl-
d
-glucosamine. These sugars were also capable of eluting [
3
H]glucosamine-labeled material from disrupted PR-A virus, which was bound to a Con A-sepharose affinity column. A major viral glycoprotein recovered from the column had the same mobility as gp85 in polyacrylamide gel electrophoresis and could be immunoprecipitated with anti-gp85 antiserum. These results suggest that the material reacting with Con A is present on the gp85 component of the viral glycoprotein. The diversity in the reactivity of the glycoproteins of transforming and nontransforming viruses with plant lectins is discussed.
Interferon Treatment of Ehrlich Ascites Tumor Cells: Effects on Exogenous mRNA Translation and tRNA Inactivation in the Cell Extract
Authors: Sen G. C. , Gupta S. L. , Brown G. E. , Lebleu B. , Rebello M. A. , Lengyel P.
Published: January 2020

We reported earlier that in cell extracts that were prepared from interferon-treated Ehrlich ascites tumor cells and preincubated and passed through Sephadex G-25 (S30
INT
), the translation of exogenous mRNA (viral and host) was impaired and the impairment could be overcome to a large extent by adding a crude tRNA preparation from Ehrlich ascites tumor cells but not from
Escherichia coli.
We find now that the rate of inactivation of some tRNA's (especially those specific for leucine, lysine, and serine) but not those of many others is faster in S30
INT
than in corresponding extracts from control cells. This increased rate of tRNA inactivation may perhaps account for the need for added RNA to overcome at least partially the impairment of translation in S30
INT
. The relationship of the increased rate of tRNA inactivation to the antiviral effect of interferon is unclear. So far no significant difference has been detected in the amount of tRNA needed to overcome the impairment of encephalomyocarditis virus RNA translation in S30
INT
between tRNA from interferon-treated cells and tRNA from control cells. Furthermore, no difference was found in the rate of inactivation in S30
INT
between leucine-specific tRNA's from interferon-treated and from control cells. tRNA's specific for leucine and lysine were not inactivated (unless very slowly) during incubation under our conditions in an extract from interferon-treated (or from control) cells unless the extract had been passed through Sephadex G-25 or dialyzed. The translation of exogenous mRNA was, however, impaired in an extract from interferon-treated cells that had not been passed through Sephadex G-25. This impairment was apparently not overcome by added tRNA.
Chromatin-Like Structures in Polyoma Virus and Simian Virus 40 Lytic Cycle
Authors: Cremisi Chantal , Pignatti Pier Franco , Croissant Odile , Yaniv Moshe
Published: January 2020

Nucleoprotein complexes containing viral DNA and cellular histones were extracted from nuclei of permissive cells infected with polyoma virus or simian virus 40 (SV40) and examined by electron microscopy. Polyoma and SV40 nucleoprotein complexes are almost identical. They appear as relaxed circular molecules consisting of 20 to 21 globular particles interconnected by thin filaments. Their contour length in 0.02 M salt is 2.7 times shorter than that of viral DNA form I obtained after dissociation of the proteins in 1 M NaCl. The nucleosomes have an average diameter of 12.5 nm. Each nucleosome contains 175 to 205 DNA base pairs condensed fivefold in length. The nucleosomes are regularly spaced on the circular molecule. The internucleosomal filaments are made of naked DNA, and each filament contains about 55 base pairs. The partial sensitivity of the nucleoprotein complex to cleavage by
Eco
R1 endonuclease suggests that the nucleosomes are not formed at specific sites on the viral genome. Faster sedimenting nucleoprotein complexes containing replicative intermediates were studied. Isopycnic centrifugation in metrizamide gradients in the absence of aldehyde fixation showed that these molecules conserved the same DNA-to-protein ratio as the form I DNA-containing complexes.
Induction of Type C Virions from Normal Rat Kidney Cells by 2-Deoxy-
d
-Glucose
Authors: Prochownik Edward V. , Panem Sandra , Kirsten Werner H.
Published: January 2020

The sugar 2-deoxy-
d
-glucose (2-DG) induced the release of type C virions from an established line of normal rat kidney (NRK) cells. Within 20 h after the addition of 5 mg of 2-DG per ml to exponentially growing NRK cultures, more than 80% of the cells expressed the mammalian type C virus interspecies-specific antigen (p30) as determined by indirect cytoplasmic immunofluorescence. Maximal virion release occurred 1 to 2 days after 2-DG was added for 24 h to the growth medium, although a low level of virion production was detected as early as 2.5 h after 2-DG treatment. Studies with inhibitors of RNA synthesis indicated a requirement for de novo RNA synthesis after the addition of 2-DG. Sensitivity of NRK cells to type C virion induction was limited to a relatively short period of in vitro growth and preceded spontaneous virion release by 8 to 10 subculture generations. A model is presented for the sequential derepression of latent type C virus information in serially propagated NRK cells.
Growth of Enveloped RNA Viruses in a Line of Chinese Hamster Ovary Cells with Deficient
N
-Acetyl-glucosaminyltransferase Activity
Authors: Schlesinger Sondra , Gottlieb Charlene , Feil Paul , Gelb Nancy , Kornfeld Stuart
Published: January 2020

Sindbis and vesicular stomatitis viruses were grown in a line (termed 15B) of Chinese hamster ovary (CHO) cells that is deficient in a specific UDP-
N
-acetylglucosamine:glycoprotein
N
-acetylglucosaminyltransferase. Both viruses replicated normally in the cell line, but the glycoproteins of the released virus migrated faster on sodium dodecyl sulfate-polyacrylamide gels than did glycoproteins of virus grown in parent CHO cells. Digestion of the viral glycoproteins with Pronase followed by gel filtration demonstrated that the glycopeptides of Sindbis-15B virus were much smaller than the glycopeptides of Sindbis-CHO virus. In addition, Sindbis-15B viral glycopeptides but not Sindbis-CHO viral glycopeptides contained terminal α-mannose residues as shown by their susceptibility to α-mannosidase digestion. These findings demonstrate that the oligosaccharide units of the glycoproteins of vesicular stomatitis and Sindbis viruses are altered when the viruses are grown in 15B cells. We conclude that the
N
-acetylglucosaminyltransferase that is missing in 15B cells normally participates in the biosynthesis of the oligosaccharide units of the viral glycoproteins, and in the absence of this enzyme incomplete oligosaccharide chains are produced. Viruses released from 15B cells appear to retain full infectivity; Sindbis-15B virus, however, showed a significant decrease in hemagglutination titer compared with that of Sindbis-CHO virus.
Replication of a Nuclear Polyhedrosis Virus in a Continuous Cell Culture of
Spodoptera frugiperda
: Microscopy Study of the Sequence of Events of the Virus Infection
Authors: Knudson D. L. , Harrap K. A.
Published: January 2020

A microscopy study of the sequence of morphogenic events of
Spodoptera frugiperda
nuclear polyhedrosis virus infection of
S. frugiperda
cells is presented which orders the sequence of replication and establishes the time scale within which the events occur. The virus entered the cell by 1 h postinfection and was uncoated. The eclipse period was 9 h and the latent period was 12 h. Polyhedron formation was detected by 18 h postinfection and continued until the deposition of the polyhedron membrane was completed by 48 h postinfection. Aberrant morphogenic characteristics of virus repeatedly passaged in the cell culture were also recorded. Adsorption, envelope morphogenesis, and release mechanisms are discussed in light of other data on in vivo and in vitro baculovirus infections.
DNA synthesis in polyoma virus infection. V. Kinetic evidence for two requirements for protein synthesis during viral DNA replication
Authors: Yu K , Cheevers W P
Published: January 2020

Protein synthesis in polyoma virus-infected cells was inhibited by 99% within 4 min after exposure to 10 mug of cycloheximide per ml. Subsequent to the block in protein synthesis, the rate of viral DNA synthesis declined via inhibition of the rate of initiation of new rounds of genome replication (Yu and Cheevers, 1976). This process was inhibited with complex kinetics: within 15 min after the addition of cycloheximide, the rate of formation of closed-circular viral DNA was reduced by about one-half. Thereafter, DNA synthesis in cycloheximide-treated cells declined more slowly, reaching a level of 10% of untreated cells only after approximately 2 h. Protein synthesis was also required for normal closure of progeny form I DNA: in the presence of cycloheximide, DNA synthesis was diverted from the production of form I to form Ic, a monomeric closed-circular DNA component deficient in superhelical turns (Yu and Cheevers, 1976). Form I is replaced by Ic with first-order exponential kinetics. It is concluded that at least two proteins are involved in the control of polyoma DNA replication. One is apparently a stoichiometric requirement involved in the initiation step of viral DNA synthesis, since this process cannot be maintained at a normal rate for more than a few minutes in the absence of protein synthesis. The second protein requirement, governing the closure of newly synthesized progeny DNA, is considered distinct from the "initiation" protein on the basis of the kinetic data.
Virus-like particles from killer, neutral, and sensitive strains of Saccharomyces cerevisiae
Authors: Adler J , Wood H A , Bozarth R F
Published: January 2020

Procedures were developed for purification of virus-like particles (VLPs) from killer, neutral, and sensitive strains of Saccharomyces cerevisiae. Morphologically similar spherical VLPs measuring 40 nm in diameter were extracted from all three phenotypes. The particles were partially purified by high-speed centrifugation through a layer of CsCl (1.26 g/cm3) and sucrose density gradient centrifugation. Gradient-purified preparations contained three centrifugal species that sedimented at approximately 43, 102, and 162S. The 43S component is considered to be an artifact. Preparations from killer strains contained three double-stranded RNA (ds-RNA) components with molecular weights of 1.19 x 10(6), 1.29 x 10(6) and 2.54 x 10(6). VLPs from neutral and sensitive strains contained only the largest ds-RNA species. VLP preparations were subsequently separated into two major density components by CsCl equilibrium gradient centrifugation. The light component banding at 1.28 to 1.30 g/cm3 was void of nucleic acid, and the heavy component banding at 1.40 g/cm3 contained only the largest ds-RNA species.
Characterization and translation of methylated and unmethylated vesicular stomatitis virus mRNA synthesized in vitro by ribonucleoprotein particles from vesicular stomatitis virus-infected L cells
Authors: Toneguzzo F , Ghosh H P
Published: January 2020

Ribonucleoprotein particles isolated from extracts of vesicular stomatitis virus (VSV) -infected L cells synthesized in vitro four classes of polyadenylated RNA sedimenting at 29S, 19S, 17S, and 13S. When synthesized in vitro in the presence of the methyl donor S-adenosyl methionine, these RNA species contained the following 5'-terminal structures: (i) m7G5ppp5'AmpAp(70%) ; (ii) m7G5'ppp5'AmpAmpNp (20%) and (iii) pppAp (10%). In the presence of the methylation inhibitor S-adenosylhomocysteine, however, the mRNA contained the 5'-terminal structures G5'ppp5'Ap (80%) and pppAp (20%). The mRNA's synthesized in vitro were translated in the homologous ascites and the heterologous wheat embryo cell-free systems. In both, the products were shown by sodium dodecyl sulfate gel electrophoresis and by immunoprecipitation to contain all five viral proteins, L, G, N, NS, and M. The presumed precursor to the G protein (G*) was also identified by fingerprint analysis. Methylated VSV mRNA was more active in protein synthesis than unmethylated mRNA in both the ascites system and the wheat embryo systems. Addition of S-adenosylmethionine stimulated translation of unmethylated mRNA in the wheat embryo but not in the ascites extract. S-adenosylhomocysteine, however, by preventing mRNA methylation inhibited the translation of unmethylated VSV mRNA in both systems. The mRNA methylating activity present in wheat embryo S-30 extracts was recovered in the ribosome-free supernatant fraction (S-150) and was insensitive to the protein synthesis inhibitor pactamycin.
Genomic complexities of murine leukemia and sarcoma, reticuloendotheliosis, and visna viruses
Authors: Beemon K L , Faras A J , Hasse A T , Duesberg P H , Maisel J E
Published: January 2020

The genetic complexities of several ribodeoxyviruses were measured by quantitative analysis of unique RNase T1-resistant oligonucleotides from 60-70S viral RNAs. Moloney murine leukemia virus was found to have an RNA complexity of 3.5 x 10(6) daltons, whereas Moloney murine sarcoma virus had a significantly smaller genome size of 2.3 x 10(6). Reticuleondotheliosis and visna virus RNAs had complexities of 3.9 x 10(6), respectively. Analysis of RNase A-resistant oligonucleotides of Rous sarcoma virus RNA gave a complexity of 3.6 x 10(6), similar to that previously obtained with RNase T1-resistant oligonucleotides. Since each of these viruses was found to have a unique sequence genomic complexity near the molecular weight of a single 30-40S viral RNA subunit, it was concluded that ribodeoxyvirus genomes are at least largely polyploid.
Bacteriophage T4 head morphogenesis. VII. Terminal stages of head maturation
Authors: Hamilton D L , Luftig R B
Published: January 2020

Several aspects of the terminal stages of T4 head maturation were investigated using ts and am mutants blocked at single steps of the assembly pathway. We had previously found that cells infected with mutants of gene 13, e.g., tsN38 and amE609, accumulated both stable (10 to 20%)- and fragile (80%)-filled head precursors (Hamilton and Luftig, 1972). Here we showed the following for such gene 13-defective, mutant-infected cells. (i) Using thin-section analysis the pool of phage precursor structures observed under nonpermissive conditions was one-third of that observed when the cells were cultured under permissive conditions. (ii) In order for complete conversion of the precursors into viable phage to occur, there were apparent requirements of metabolic energy, protein, and DNA synthesis. (iii) The intracellular DNA pool under nonpermissive conditions exhibited a 50% distribution between 63S (mature size) and 200 S (concatenate size) DNA, with the latter DNA serving as a precursor pool. Further, this DNA pool when spread onto a protein monolayer exhibited a dispersed array of DNA, strands around a core, which was less dense than that found for the greater than 1,000S DNA concatenate isolated from gene 49-defective infected cells. (iv) When precuations were taken to stabilize the head precursors, such as lysis of the cells into glutaraldehyde, there was a 30% increase in the yield of 1,200S filled heads. Correlating these results and previous results concerning gene 49-defective unfilled heads, we propose that there are several forms of gene 13 fragile head precursors which serve as intermediates between gene 49 unfilled heads and gene 13 stable filled heads. We cannot, however, rule out the possibility that all gene 13-defective heads represent a single class of unstable particles, which decay slowly. In either case, we have shown that gene 13-defective particles are unstable to some degree inside the cell and are highly unstable outside the cell; yet all particles can still be efficiently converted to phage in vivo.
Identification and preliminary characterization of a mutant defective in the bacteriophage T4-induced unfolding of the Escherichia coli nucleoid
Authors: Snustad D P , Tigges M A , Parson K A , Bursch C J , Caron F M , Koerner J F , Tutas D J
Published: January 2020

The nucleoids of Escherichia coli S/6/5 cells are rapidly unfolded at about 3 min after infection with wild-type T4 bacteriophage or with nuclear disruption deficient, host DNA degradation-deficient multiple mutants of phage T4. Unfolding does not occur after infection with T4 phage ghosts. Experiments using chloramphenicol to inhibit protein synthesis indicate that the T4-induced unfolding of the E. coli chromosomes is dependent on the presence of one or more protein synthesized between 2 and 3 min after infection. A mutant of phage T4 has been isolated which fails to induce this early unfolding of the host nucleoids. This mutant has been termed "unfoldase deficient" (unf-) despite the fact that the function of the gene product defective in this strain is not yet known. Mapping experiments indicate that the unf- mutation is located near gene 63 between genes 31 and 63. The folded genomes of E. coli S/6/5 cells remain essentially intact (2,000-3,000S) at 5 min after infection with unfoldase-, nuclear disruption-, and host DNA degradation-deficient T4 phage. Nuclear disruption occurs normally after infection with unfoldase- and host DNA degradation-deficient but nuclear disruption-proficient (ndd+), T4 phage. The host chromosomes remain partially folded (1,200-1,800S) at 5 min after infection with the unfoldase single mutant unf39 x 5 or an unfoldase- and host DNA degradation-deficient, but nuclear disruption-proficient, T4 strain. The presence of the unfoldase mutation causes a slight delay in host DNA degradation in the presence of nuclear disruption but has no effect on the rate of host DNA degradation in the absence of nuclear disruption. Its presence in nuclear disruption- and host DNA degradation-deficient multiple mutants does not alter the shutoff to host DNA or protein synthesis.
Nuclear membrane changes in herpes simplex virus-infected BHK-21 cells as seen by freeze-fracture
Authors: Haines H , Baerwald R J
Published: January 2020

The freeze-fracture technique, which produced high-resolution replicas of large internal faces of membranes, was used for an ultrastructural study of the nuclei of herpes simplex virus-infected BHK-21 cells and mock-infected controls. Crystalline arrays of viral nucleocapsids were found in the nucleoplasm of infected cells, and numerous nuclear membrane "blebs" and protrusions were observed. The numerous areas of membrane distortions were not found to contain nuclear pores. In addition, specific areas of normal protein intramembranous particles are deleted from certain areas of the nuclear membrane as a result of herpes simplex virus, type 2, infection.
DNA-negative temperature-sensitive mutants of herpes simplex virus type 1: patterns of viral DNA synthesis after temperature shift-up
Authors: Schaffer P A , Bone D R , Courtney R J
Published: January 2020

Temperature-sensitive mutants of herpes simplex virus type 1 belonging to four DNA- complementation groups exhibited two distinct patterns of viral DNA synthesis after shift-up to the nonpermissive temperature. In cultures infected with mutants belonging to complementation groups A, C, and D, little or no viral DNA was synthesized after shift-up. In cultures infected with a mutant in complementation group B, nearly normal amounts of viral DNA were synthesized after shift-up.
Initiation of DNA synthesis by the avian oncornavirus RNA-directed DNA polymerase: tryptophan tRNA as the major species of primer RNA
Authors: Folk W R , Faras A J
Published: January 2020

The major species of primer RNA required for the initiation of DNA synthesis by the Rous sarcoma virus RNA-directed DNA polymerase can be aminoacylated by tryptophan. Furthermore, an intact 3' terminus is required for the primer to function in the initiation of DNA synthesis.
Polyoma and cell DNA synthesis in mouse L cells temperature sensitive for the replication of cell DNA
Authors: Sheinin
Published: January 2020

Polyoma (Py) virus multiplies, at 34 and 38.5 C, in wild-type (WT-4) and in ts A1S9 mouse L cells, which are temperature sensitive for growth and for DNA replication (R. Sheinin, 1976; L. H. Thompson et al., 1970). De novo synthesis of double-stranded, fully covalently closed Py DNA has been shown to proceed by semiconservative replication in WT-4 and ts A1S9 cells at the permissive and nonpermissive temperatures. Cell DNA is made late during infection, by both cell types and at both temperatures. Semiconservative replication of cell DNA proceeds in Py-infected WT-4 cells incubated at 34 or at 38.5 C and in Py-infected ts A1S9 cells incubated at 34 C. In virus-infected ts A1S9 cells incubated at 38.5 C, cell DNA synthesis appears to proceed almost entirely by a process analogous to repair replication. The inability of ts A1S9 cells to produce large-molecular-weight chromosomal DNA strands, at 38.5 C, by the normal mechanism is not overcome by Py infection.
Process of infection with bacteriophage phi X 174 XXXVIII. Replication of phi chi 174 replicative form in vivo
Authors: Fukuda A , Sinsheimer R L
Published: January 2020

The replication of bacteriophage phi X 174 replicative-form DNA has been studied by structural analysis of pulse-labeled replicative-intermediate molecules. Such intermediates were identified by pulse-labeling with [13H]thymidine and separated into four major fractions (A, B, C, and D) in a propidium diiodide-cesium chloride buoyand density gradient. Sedimentation analysis of each of these fractions suggests the following features of phi X replicative-form DNA replication in vivo. (i) At the end of one cycle of replication, one daughter replicative form (RFII) contains a nascent plus (+) strand of the unit viral length, and the other daughter RFII contains small fragments of nascent minus (-) strand. (ii) Asymmetry is also associated with production of the first supercoiled RFI after addition of pulse label in that only the minus strand becomes radioactive. (iii) A supercoiled DNA (RFI') seems to occur in vivo. This DNA is observed at a position of greater density in a propidium diiodide-cesium chloride buoyant density gradient than normal RFI. (iv) A novel DNA component is observed, at a density greater than RFI, which releases, in alkali, a plus strand longer (1.5 to 1.7 times) than the unit viral length. These results are discussed in terms of the possible sequence of events in phi X 174 replicative-form replication in vivo.
Genome localization of simian virus 40 RNA species
Authors: Khoury G , Carter B J , Ferdinand F J , Howley P M , Brown M , Martin M A
Published: January 2020

The topographical locations on the simian virus 40 (SV40) genome of the templates for virus-specific RNA species present late in the lytic infection were determined by RNA-DNA hybridization experiments with the Hind restriction enzyme fragments. Two classes of late virus-specific cytoplasmic mRNA's can be separated on the basis of either sedimentation properties in neutral sucrose or electrophoretic mobility in polyacrylamide gels. In the 16S class, two species of RNA were identified by hybridization experiments. One of these species was complementary to sequences of the early template on the minus (E) strand (0.175 to 0.655 map units), and the other more abundant species was complementary to sequences present in the late template on the plus (L) strand (0.655 to 0.175 map units). In addition two species were detected in the 16S class of late cytoplasmic virus-specific mRNA. One of these species was the major late RNA detected and consisted of a polyadenylated transcript complementary to the plus (L) DNA strands of Hind fragments K, F, J, and G (0.945 to 0.175 map units). This species appears to specify the major capsid protein (VP1). A less abundant nonpolyadenylated 16S RNA species complementary to the plus (L) strands of Hind fragments C, D, and E (0.655 to 0.945 map units) may result from post-transcriptional processing or nonspecific degradation of the 19S viral RNA complementary to the plus (L) strand.
Regulatory mechanism of simian virus 40 gene expression in permissive and in nonpermissive cells
Authors: Graessmann A , Graessmann M , Mueller C
Published: January 2020

Primary or continuous lines of mouse cells (3T3) are nonpermissive for simian virus 40 (SV40). Abortively infected cells synthesize tumor antigen (T antigen but not viral DNA and virus capsid protein (V antigen). V antigen, however, was obtained when SV40 DNA was injected into 3T3 cells. This late gene expression also appears to be correlated with the quantity of injected DNA molecules per 3T3 cell. T antigen formation can be detected after microinjection of only 1 to 2 DNA molecules, but the intensity of intranuclear T antigen fluorescence is significantly brighter with injection of higher concentrations of viral DNA. In permissive cells (TC7), early and late SV40 gene expression is directly related to the number of injected molecules. Microinjection of 1DNA molecule induced T and V antigen formation with the same efficiency as microinjection of 2,000 to 4,000 molecules. The question of weather late SV40 gene expression is directly related to the quantity of an early virus-specific product was approached by microinjection of early SV40 complementary RNA together with small amounts of viral DNA. V antigen was obtained in a high proportion of recipient 3T3 cells at conditions where microinjection of viral DNA alone induced T but not V antigen synthesis.
Escherichia coli capsule bacteriophages. VIII. Fragments of bacteriophage 28-1
Authors: Rieger D , Freund-Mölbert E , Stirm S
Published: January 2020

As described previously, a host capsule depolymerase activity is associated with the particles of Escherichia coli capsule bacteriophage 28-1. This is a large virus with a long, contractile tail terminating in a base plate with spikes. In the present work, isolated virions were exposed to a variety of dissociative reagents and conditions. They were then tested for residual infectivity and depolymerase activity, as well as inspected under an electron microscope. Very mild acid treatment (10 to 15 min at pH 4.0 and 37 C) was found to cause a specific detachment of some phage spikes, together with a moderate drop in both infectivity and depolymerase activity. Large batches of viruses were fragmented in this manner, and the detached spikes were isolated. The host capsule depolymerase activity was found to be associated with these organelles. In negatively stained preparations, the spikes exhibited a length of approximately 18 nm and a thickness of about 5 nm. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis, they were found to contain polypeptides with molecular weights of 80,000 and 145, 000.
In vivo and in vitro synthesis of adenovirus type 2 early proteins
Authors: Saborio J L , Oberg B
Published: January 2020

The synthesis of adenovirus type 2 (Ad2)-induced early polypeptides was examined in vivo and in vitro by a combination of sodium dodecyl sulfate-polyacrylamide gel electrophoresis alone and specific immunoprecipitation followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Analysis of total [35S]methionine-labeled polypeptides synthesized in vivo at 3 h postinfection allowed us to detect in infected cells at lease 13 distinct polypeptides that are either absent or less conspicuous in extracts from mock-infected cells. These Ad2-induced early polypeptides have molecular weights ranging from 72 x 10(3) to 10.5 x 10(3) and have accordingly been designated as E72K to E10.5K. Nine of the in vivo synthesized early polypeptides can be precipitated specifically from infected cell extracts by antisera with specificity against early adenovirus proteins. In vitro translation of mRNA extracted from mock-infected cells and from Ad2-infected cells was carried out in preincubated Ehrlich ascites cell extracts. All the early Ad2-induced polypeptides identified in the extracts from infected cells labeled in vivo were also detected among the polypeptides immunoprecipitated specifically from the in vitro reaction mixtures programmed by RNA extracted at 4 h postinfection from Ad2-infected cells.
Biochemistry of DNA-defective mutants of bacteriophage T4. VI. Biological functions of gene 42
Authors: North T W , Stafford M E , Mathews C K
Published: January 2020

Bacteriophage T4 gene 1 and 42 amber mutants (defective in deoxynucleoside monophosphate kinase and deoxycytidylate hydroxymethylase, respectively) are able to synthesize DNA in cell-free lysates prepared as described by Barry and Alberts (1972), in contrast to their inabliity to do so in plasmolyzed and toluenized cell systems. Addition of extracts containing an active gene 1 or 42 product has no effect on synthesis in lysates defective in the respective gene. Thus, if these enzymes do play additional direct roles in replication, these roles are not manifest in the lysed-cell system. The gene 42 mutant am N122/m, a double mutant bearing an additional defect in DNA polymerase, is unable to synthesize DNA in these lysates. This inability is overcome by addition of extracts containing an active T4 DNA polymerase. m is a leaky amber mutation which reduces DNA polymerase activity to a very low level. However, this level is high enough to allow positive genetic complementation tests with gene 43 mutants. Two other gene 42 amber mutants contain additional defects: am 269 induces only half the normal level of DNA polymerase, and am C87 fails to induce a detectable level of thymidylate synthetase. These defects do not result from pleiotropic effects of the gene 42 mutations. In plasmolyzed cells, temperature-sensitive gene 42 mutants fail to synthesize DNA under conditions where replication forks and 5-hydroxymethyl-dCTP are present. This supports the idea that the gene 42 protein is directly involved in DNA synthesis.
Newcastle disease virus-specific RNA: poly(A)-containing and poly(A)-deficient transcripts as revealed by chromatography on poly(U)-sepharose
Authors: Varich N L , Lukashevich I S , Kaverin N V
Published: January 2020

Total [3H]uridine-labeled, virus-specific RNA from Newcastle disease virus-infected cells was fractionated by poly(U)-sepharose chromatography and analyzed by rate zonal gradient centrifugation. The sedimentation pattern of both eluted and nonadsorbed RNA resembled that of the total RNA. However, nonadsorbed RNA was enriched in 50S material, ant its 18S peak was broader and slightly shifted towards the top of the gradient. Poly(U-sepharose chromatography of isolated 18S RNA and 24S RNA resulted in the separation of poly(A)-containing RNA and poly(A)-deficient RNA. In the former the percentage of adenosine content represented by poly(A) sequences was estimated as 10 to 12% (for 18S RNA) or approximately 6.0% (for 24S RNA). The size of poly(A) fragments as measured by their sedimentation rate was the same for 18S and 24S RNA. Polyacrylamide gel electrophoresis of poly(A)-containing RNA revealed a characteristic pattern closely resembling the pattern of nonchromatographed 18S and 24S RNA. The pattern of poly(A)-deficient RNA was heterogenous, and for 18S RNA it shifted towards the anode. The possible origin of poly(A)-deficient transcripts is discussed.