bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of tumor antigen synthesis by simain virus 40 gene A
Authors: Tegtmeyer P , Schwartz M , Collins J K , Rundell K
Published: January 2020

Simian virus 40 gene A has previously been shown to promote the replication of viral DNA and the transcription of late viral RNA in productive infection and to maintain the growth characteristics of some transformed cells. The present study examines the effect of the A function on proteins synthesized during productive and transforming infections. Under restrictive conditions, temperature-sensitive A mutants induce the overproduction of a 100,000-dalton protein both in productively infected monkey cells and in transformed rabbit cells. Immunoprecipitation of the induced protein with antisera, prepared against simian virus 40-induced tumors in hamsters, was used to identify the induced protein as tumor antigen. The same protein can be precipitated from extracts of cells infected by wild-type virus but not from uninfected cells. Furthermore, the mutant-induced protein is more rapidly degraded in vivo and is less tightly bound to intranuclear components than the protein induced by wild-type virus. The presence of the same virus-induced protein in infected cells from different species and the altered behavior of that protein in mutant infection strongly suggest that the protein is virus coded. Because the protein is large enough to account for the entire coding capacity in the early region of the simian virus 40 genome, the 100,000-dalton protein may well be the primary product of the only early gene identified by complementation studies, the A gene. If the 100,000-dalton protein that is overproduced in mutant infection is the A protein and the only early protein, then functional wild-type A protein must regulate its own synthesis in both productive and transforming infections.
Isolation and characterization of prophage mutants of the defective Bacillus subtilis bacteriophage PBSX
Authors: Thurm P , Garro A J
Published: January 2020

Bacillus subtilis mutants with lesions in PBSX prophage genes have been isolated. One of these appears to be a regulatory mutant and is defective for mitomycin C-induced derepression of PBSX; the others are defective for phage capsid formation. All of the PBSX structural proteins are synthesized during induction of the capsid defective mutants; however, several of these proteins exhibit abnormal serological reactivity with anti-PBSX antiserum. The two head proteins X4 and X7 are not immunoprecipitable in a mutant which fails to assemble phage head structures. In the tail mutant, proteins X5 and X6 are not immunoprecipitable, tails are not assembled, and a possible tail protein precursor remains uncleaved. The noninducible mutant does not synthesize any PBSX structural proteins after exposure to mitomycin C. The mutation is specific for PBSX since ø105 and SPO2 lysogens of the mutant are inducible. All of the known PBSX-specific mutations were shown to be clustered between argC and metC on the host chromosome. In addition, the metC marker was shown to be present in multiple copies in cells induced for PBSX replication. This suggests that the derepressed prophage replicates while still integrated and that replication extends into the adjacent regions of the host chromosome.
Restitution of infectivity to spikeless vesicular stomatitis virus by solubilized viral components
Authors: Bishop D H , Repik P , Obijeski J F , Moore N F , Wagner R R
Published: January 2020

Noninfectious spikeless particles have been obtained from vesicular stomatitis virus (VSV, Indiana serotype) by bromelain or Pronase treatment. They lack the viral glycoprotein (G) but contain all the other viral components (RNA, lipid, and other structural proteins). Triton-solubilized VSV-Indiana glycoprotein preparations, containing the viral G protein as well as lipids (including phospholipids), have been extracted from whole virus preparations, freed from the majority of the detergent, and used to restore infectivity to spikeless VSV. The infectivity of such particles has been found to be enhanced by poly-L-ornithine but inhibited by Trition or homologous antiserum pretreatment. Heat-denatured glycoprotein preparations were not effective in restoring the infectivity to spikeless VSV. Heterologous glycoprotein preparations from the serologically distinct VSV-New Jersey serotype were equally capable of making infectious entities with VSV-Indiana spikeless particles, and the infectivity of these structures was inhibited by VSV-New Jersey antiserum but not by VSV-Indiana antiserum. Purified, detergent-free glycoprotein selectively solubilized from VSV-Indiana by the dialyzable detergent, octylglucoside, also restored infectivity of spikeless virions of VSV-Indiana and VSV-New Jersey.
Resolution of the DNA strands of the specialized transducing bacteriophage lambda-h80C 1-857 dargF
Authors: Sens D , Eshenbaugh D , James E
Published: January 2020

The DNA strands of lambdoid phages with deletions or substitutions of the guanine plus cytosine-rich region in the left arm are not resolvable by complexing with poly UG followed by centrifugation in CsCl. This work describes a completely general procedure for the strand resolution of these phages by hybridization with fragments of separated strands of the parent phage. In particular, resolution of the DNA strands of the specialized transducing phage lambda-h80C1-857dargF is described, and evidence is presented which indicates that argF is transcribed from the r strand.
Association of vesicular stomatitis virus glycoprotein with virion membrane: characterization of the lipophilic tail fragment
Authors: Schloemer R H , Wagner R R
Published: January 2020

The proteolytic enzyme, thermolysin, degraded the external segment of the membrane glycoprotein of intact vesicular stomatitis (VS) virions but left behind a small nonglycosylated fragment, presumably embedded in the virion membrane. Other proteases generated membrane-associated glycoprotein fragments differing somewhat in molecular weight. The thermolysin-resistant, virion-associated fragment, which can be selectively solubilized by either Triton X-100 or chloroform/methanol, has a molecular weight of 5,200. Amino acid analysis of the glycoprotein fragment reveals a preponderance of hydrophobic amino acids (64% of the residues); the amino-terminal amino acid is alanine as determined by dansylation. Cyanogen bromide digestion of the tail fragment generated two peptides, confirming the presence of one methionine residue per thermolysin-resistant glycoprotein fragment. The secondary structure of this glycoprotein tail peptide is maintained by at least one disulfide bridge. Thermolysin treatment is isolated VS viral glycoprotein in the presence of Triton X-100 also generated a hydrophobic peptide fragment which is very similar to the virion-associated glycoprotein fragment. The amino acid terminus of intact glycoprotein was also found to be alanine as was its dansylated Triton-micellar fragment that resisted thermolytic degradation; this finding suggests that the amino-terminal end of the VS viral glycoprotein is embedded in the virion membrane. These results suggest that the VS viral glycoprotein is an amphipathic molecule, the hydrophilic portion of which contains all the carbohydrate and a lipophilic tail segment which forms lipid or detergent micelles, thus rendering it resistant to proteolysis.
Abortive infection of L cells by influenza virus: absence of virion RNA synthesis
Authors: Avery R J
Published: January 2020

Influenza virus multiplies productively in chick cells and abortively in L cells. The infecting influenza virus RNA genomes are less stable in infected L cells than in infected chick cells. However, transcription of the virus genome in L cells, while reduced in rate, is not decreased in extent. There is no detectable synthesis of virion RNA in L cells, and this is the most likely cause of the abortive infection.
Discriminative effect of rifampin of RNA replication of various RNA bacteriophages
Authors: Engelberg H , Brudo I , Israeli-Reches M
Published: January 2020

Rifampin interferes exclusively with RNA replication in vivo of the group I phages MS2, f2, and R17, whereas QbetaRNA replication is unaffected by the drug. In addition, rifampin has a discriminative effect of group I phage RNA replication. In the experimental system employed by us the antibiotic differentially interferes with the synthesis of minus RNA strands in f2, whereas it has almost no effect on the synthesis of progeny plus strands. In MS2, the drug differentially arrests the synthesis of progeny plus strands and almost fails to affect the synthesis of minus RNA strands. In R17 both steps of its RNA replication are affected by rifampin, although each step is only partially (approximately 50%) inhibited. The relation of the present results to the possible role of bacterial proteins and tertiary structure of phage RNA in the process of template recognition is discussed.
Demyelination and cytopathic effects in cultures of mammalian dorsal root ganglia infected with encephalomyocarditis virus
Authors: Oren R , Shahar A , Monzain R
Published: January 2020

Replication of encephalomyocarditis virus and its cytopathic effects were studied in myelinated cultures of dorsal root ganglia obtained from newborn mice. Six hours after infection virus progeny was detected in the culture. At 24 h the virus titer reached 2 times 10(6) PFU per culture and remained at this level until 48 h. The first cytopathic alterations began at 24 h and consisted of rounding of Schwann and satellites cells and their detachment from neurons. Later, bead-like swellings of the myelin appeared along the axons followed by splitting and degeneration of lamellae. The cytopathic effect in the neurons started 29 h after infection, reaching complete neuronolysis at 48 h. Virus particles, scattered or arranged in crystal-like aggregates, were first seen in the cytoplasm of glial cells and then in neurons and axons.
Biological functions of the bacteriophage T3 SAMase gene
Authors: Krueger D H , Presber W , Hansen S , Rosenthal H A
Published: January 2020

Certain differences between phage T3 on the one hand and T3sam- and T7 on the other hand indicate that the T3-coded SAMase function is responsible (i) for the development of the pseudolysogenic state by preventing T3 DNA methylation, and (ii) for the partial protection of the phage DNA against restriction by the P system.
Association of endonuclease activity with serotypes belonging to the three subgroups of human adenoviruses
Authors: Marusyk R G , Morgan A R , Wadell G
Published: January 2020

Endonuclease activity has been detected in association with highly purified virions, pentons, and/or dodecons of adenovirus types 2, 3, 5, 9, 12, 15, and 16. Only single-strand scissions in substrate DNA were detected. The nuclease activity was detected by a highly sensitive ethidium bromide fluorimetric assay procedure.
Lysozymes from bacteriophages T3 and T5
Authors: DeMartini M , Halegoua S , Inouye M
Published: January 2020

Lysozymes produced in host cells infected with bacteriophages T3 and T5 were found to have the same enzymatic specificity toward the peptidoglycan from Escherichia coli as T7 phage lysozyme, which has been shown to be an N-acetylmuramyl-L-alanine amidase.
Adenovirus binds to rat brain microtubules in vitro
Authors: Luftig R B , Weihing R R
Published: January 2020

We have found by negative staining electron microscopy that when similar concentrations of adenovirus and reovirus (viruses of about the same diameter, 75 to 80 nm, and density, 1.34 to 1.36 g/cm3) were incubated with a carbon support film containing microtubules, 72% of adenovirus on the grid, but only 32% (equivalent to random association) of reovirus, were associated with microtubules. Similar concentrations of both larger and smaller particles, such as polystyrene latex spheres and coliphage f2, also exhibited a low degree of interaction, viz., 17 to 37%, with microtubules. Moreover, 90% of microtubule-associated adenovirus binds to within +/- 4 nm of the edge of microtubules, but lower fractions (again equivalent to a random association) of the other particles bind to the edge of the microtubules. The mechanism behind this phenomenon, which we denote as "edge binding," is presently obscure; however, it provides us with a second, albeit empirical, method to distinguish between the microtubular association of adenovirus and other particles. We found that edge binding of adenovirus also occurred when adenovirus was initially placed on the carbon support film and then incubated with microtubules and when adenovirus and microtubules were mixed prior to placement on the support. In contrast, reovirus or the other particles prepared by similar techniques exhibited a random amount of edge binding. The binding of adenovirus appears to involve the hexon capsomers of the virion since (i) high resolution electron micrographs showed that the edge of the virus was in contact with the edge of the microtubules, and (ii) adenovirions briefly treated with formamide to remove pentons and fibers bind as efficiently as intact virions. Core structures, which were obtained by further formamide degradation of the virion, do not associate with microtubules. These observations support the hypothesis of Dales and Chardonnet (1973) that the transport of adenovirions within infected cells is mediated by interaction with microtubules.
Identification of bacteriophage T4-specific precursor tRNA by using a host mutant defective in the methylation of tRNA
Authors: Björk G R
Published: January 2020

A mutant of Escherichia coli K-12 that is defective in the synthesis of 5-methyluridine (ribothymidine) in tRNA was used to identify precursors to phage T4-specific tRNA. The precursor molecules, isolated by gel filtration, were more than twice the size of tRNA. This method is suitable for isolation of rather large amounts of such precursor molecules.
Isolation and preliminary characterization of temperature-sensitive mutants of measles virus
Authors: Haspel M V , Duff R , Rapp F
Published: January 2020

Twenty-four genetically stable temperature-sensitive mutants of measles virus were isolated after mutangenesis by 5-azacytidine, 5 fluorouracil, or proflavine. The restricted replication of all mutants at 39 C was blocked subsequent to cell penetration and could not be attributed to heat inactivation of virus infectivity. Complementation analysis was made possible through the use of poly-L-ornithine. The members of one complementation group exhibited wild-type RNA synthesis at the nonpermissive temperature and induced the synthesis of virus antigens. These mutants were found defective in both hemolysin antigen synthesis and cell fusion "from within," supporting the unitary hypothesis for these functions. The members of the other two complementation groups synthesized neither virion RNA nor detectable virus antigens at the nonpermissive temperature.
Adenovirus type 2 DNA replication. II. Termini of DNA replication
Authors: Schilling R , Weingärtner B , Winnacker E L
Published: January 2020

Complete, mature adenovirus type 2 DNA molecules were isolated from virus-infected HeLa cells, pulse-labeled at 20 h postinfection in [3H]thymidine pulses shorter than the time necessary for one round of viral DNA replication. After digestion with the restriction endonucleases Eco RI, Hpa I, and Hind III, a temporal order of synthesis of different regions of the viral genome was established from the relative specific radioactivities in the restriction enzyme fragments. A comparison with the physical order of these fragments revealed the existence of two termini of DNA replication towards both the molecular right and left ends, respectively, of the viral chromosome.
Transformation of primary rat kidney cells by fragments of simian virus 40 DNA
Authors: Abrahams P J , Mulder C , Van De Voorde A , Warnaar S O , van der Eb A J
Published: January 2020

Linear simian virus 40 (SV40) DNA molecules of genome length and DNA fragments smaller than genome length when prepared with restriction endonucleases and tested for transforming activity on primary cultures of baby rat kidney cells. The linear molecules of genome length (prepared with endonucleases R-EcoRI, R-BamHI, and R-HpaII or R-HapII), a 74% fragment (EcoRI/HpaII or HapII-A), and a 59% fragment (BamHI/HapII-A) could all transform rat kidney cells with the same efficiency as circular SV40 DNA. All transformed lines tested contained the SV40-specific T-antigen in 90 to 100% of the cells, which was taken as evidence that the transformation was SV40 specific. The DNA fragments with transforming activity contained the entire early region of SV40 DNA. Endo R-HpaI, which introduced one break in the early region, apparently inactivated the transforming capacity of SV40 DNA, since no transformation was observed with any of the three HpaI fragments tested. Attempts were made to rescue infectious virus from some of the transformed lines by fusion with permissive BSC-1 cells. Infectious virus was only recovered from the cells transformed by circular form I DNA. No infectious virus could be isolated from any of the other types of transformed cells.
Host range studies of FLOPC-1 murine myeloma C particles
Authors: Krueger R G
Published: January 2020

The host range of the C particle produced by FLOPC-1 myeloma cells, FLOPC-1 murine myeloma-associated virus (FL-MuMAV), was assessed in terms of its ability to productively infect and/or induce new viral antigens in a variety of different cell lines. Production of C particle-like structures by cells exposed to FL-MuMAV) was determined by incorporation of [3H]uridine into particles with a density of 1.16 g/ml and/or measurement of RNA-dependent DNA polymerase activity in concentrated culture medium. to FL-MuMAV was capable of infecting NIH/3T3, normal rat kidney (NRK) cell, BALB/c 3T3, and the A31 clone of BALB/3T3 cells but not rabbit cell line, SIRC. Thus, it is an N, B-tropic murine virus as replication in NRK cells has been shown not to delineate a group of murine viruses with a separate host range (M. M. Lieber, C. J. Sherr, and G. J. Todero, 1974). Further neoantigens, reactive with anti-FL-MuMAV serum, were detected on infected cells. Production of the MuMAV-like particle and MuMAV-associated cell antigens in infected NIH/3T3 and NRK cells persisted for three subcultures. The limited production could not be explained by the lack of an RNA-dependent DNA polymerase or high-molecular-weight RNA as the particles possessed both of these properties. The particles produced by infected NIH/3T3 or NRK cells were antigenically and physicochemically similar to FL-MuMAV and not K-MuLV. The MuMAV-like particles produced by infected NIH/3T3 were capable of limited replication in NIH/3T3 and and BALB/3T3 cells, whereas NRK-MuMAV replicated for a limited period in NIH/3T3, NRK, and SIRC cells; i.e., they had a different host range than FL-MuMAV. The particles produced by infected BALB/3T3 and A31 cells had the same host range as FL-MuMAV. In certain situations, isotopically labeled particles with a density of 1.16 g/ml were produced which appeared to lack RNA-dependent DNA polymerase.
Altered DNA synthesis in a mutant of Salmonella typhimurium that channels bacteriophage P22 toward lysogeny
Authors: Steinberg B , Gough M
Published: January 2020

Pox-1, a mutant of Salmonella typhimurium, strongly channels P22 toward lysogeny. Viral DNA synthesis in this slow-growing mutant is delayed to a greater extent than viral protein synthesis. The relative enhancement of c2 repressor synthesis results in much higher repressor/DNA synthesis ratios in Pox-1 than in wild-type cells. This probably accounts for the high frequency of lysogenization.
Polyamines in vaccinia virions and polypeptides released from viral cores by acid extraction
Authors: Lanzer W , Holowczak J A
Published: January 2020

Vaccinia virions propagated in the presence of [3H]ornithine were found to contain two labeled polyamines, spermine and spermidine. In complete virions the ratio of radioactively labeled spermine to spermidine was about 1:10, whereas in viral cores the ratio was 2:5. This suggests that some spermidine was preferentially lost during the conversion of virions to cores or that spermidine was present in the virions both inside and outside the core structure. Addition of [3H]ornithine to vaccinia virus-infected cells as late as 6 h postinfection demonstrated that, although the conversion of this precursor to polyamines was reduced by 50% or more as compared to mock-infected cells, complete inhibition of polyamine synthesis did not occur. Two percent or less of the total radioactivity associated with virions grown in the presence of [3H]ornithine was found to be acid soluble. Polyacrylamide gel electrophoretic analysis showed that all the structural polypeptides were labeled when virions were propagated in the presence of [3H]ornithine. When cores labeled with a mixture of 14C-labeled amino acids were extracted with 0.25 N H2SO4, 12 to 15% of the labeled core polypeptides were released and could be precipitated with acetone. About 40% of [3H]arginine-labeled polypeptides associated with cores were extracted with acid. Four polypeptides or groups of polypeptides were resolved after polyacrylamide gel electrophoresis analysis of the acid-soluble fraction of cores with molecular weights of about 58,000, 34,000, 24,000 and 10,000 to 12,000. About 40% of the [3H]arginine radioactivity extracted from cores coelectrophoresed with the 10,000 to 12,000-molecular weight polypeptide, indicating that this may represent an arginine-rich, histone-like structural polypeptide of the virion.
Bacteriophage T4 baseplate components. III. Location and properties of the bacteriophage structural thymidylate synthetase
Authors: Kozloff L M , Crosby L K , Lute M
Published: January 2020

Two T4D thymidylate synthetase (td) temperature-sensitive mutants have been isolated and characterized. Both mutants produce heat-labile phage particles. This observation supports the view that this viral-induced protein is a phage structural component. Further, antiserum to td has been shown to block a specific step in tail plate morphogenesis. The results indicated that the td protein is largely covered by the T4D tail plate gene 11 protein. Since the phageinduced dihydrofolate reductase (dfr) also is partially covered by the gene 11 protein, it appears that td was adjacent to the tail plate dfr. This location has been confirmed by constructing a T4D mutant which is dfrtstdts and showing that these two tail plate constituents interact and give altered physical properties to the phage particles produced. A structural relationship for the tail plate folate, dfr, and td has been reported.
Complementation between temperature-sensitive and deletion mutants of reovirus
Authors: Spandidos D A , Graham A F
Published: January 2020

A very low level of complementation has been found in conventional crosses between various classes of temperature-sensitive (ts) mutants of reovirus. A more definitive test for complementation was devised through a plaque assay on cell monolayers mixedly infected with defective reovirions lacking the L1 segment and prototype ts mutants from one or other of the known classes of reovirus mutants. An increase in the number of plaques on the mixedly infected plates over that on control plates infected with defective virions or ts mutants alone indicated that the ts mutant had been complemented by the defective virus. Class A, B, D, F, and G mutants were complemented at 39 C by the defective viruses, whereas class C and E mutants were not. In tests to determine whether complementation was reciprocal it was found that the defective virions were complemented by a class G mutant but not by the class C mutant. This and previous work (D.A. Spandidos and A. F. Graham, 1975) has therefore shown that of the seven known classes of ts mutants the class C mutant is the only one that neither complements nor is complemented by the defective virions. For this reason the class C ts mutation has been assigned to the L1 segment of the viral genome.
Thermolabile reverse transcriptase of a mammalian leukemia virus mutant temperature sensitive in its replication and sarcoma virus helper functions
Authors: Tronick S R , Stephenson J R , Verma I M , Aaronson S A
Published: January 2020

Three temperature-sensitive mutants of the Rauscher strain of murine leukemia virus are defective in early post-penetration functions required both for leukemia virus infection and for initiation of transformation of cells by their pseudotypes of murine sarcoma virus. In the present study, the reverse transcriptase of one of these mutants (ts 29) is shown to be thermolabile compared with the enzymes of the wild-type virus and several other temperature-sensitive mutants. These findings provide evidence that the reverse transcriptase is required both for leukemia virus infection and for initition of transformation by the replication-defective murine sarcoma virus genome.
Homology between avian oncornavirus RNAs and DNA from several avian species
Authors: Shoyab M , Baluda M A
Published: January 2020

3H-labeled 35S RNA from avian myeloblastosis virus (AMV), Rous associated virus (RAV)-0, RAV-60, RAV-61, RAV-2, or B-77(w) was hybridized with an excess of cellular DNA from different avian species, i.e., normal or leukemic chickens, normal pheasants, turkeys, Japanese quails, or ducks. Approximately two to three copies of endogenous viral DNA were estimated to be present per diploid of normal chicken cell genome. In leukemic chicken myeloblasts induced by AMV, the number of viral sequences appeared to have doubled. The hybrids formed between viral RNA and DNA from leukemic chicken cells melted with a Tm 1 to 6 C higher than that of hybrids formed between viral RNA and normal chicken cell DNA. All of the viral RNAs tested, except RAV-61, hybridized the most with DNA from AMV-infected chicken cells, followed by DNA from normal chicken cells, and then pheasant DNA. RAV-61 RNA hybridized maximally (39%) with pheasant DNA, followed by DNA from leukemic (34%), and then normal (29%) chicken cells. All viral RNAs tested hybridized little with Japanese quail DNA (2 to 5%), turkey DNA (2 to 4%), or duck DNA (1%). DNA from normal chicken cells contained only 60 to 70% of the RAV-60 genetic information, and normal pheasant cells lacked some RAV-61 DNA sequences. RAV-60 and RAV-61 genomes were more homologous to the RAV-0 genome than to the genome of RAV-2, AMV, or B-77(s). RAV-60 and RAV-61 appear to be recombinants between endogenous and exogenous viruses.
Synthesis of herpes simplex virus, vaccinia virus, and adenovirus DNA in isolated HeLa cell nuclei. I. Effect of viral-specific antisera and phosphonoacetic acid
Authors: Bolden A , Aucker J , Weissbach A
Published: January 2020

Purified nuclei, isolated from appropriately infected HeLa cells, are shown to synthesize large amounts of either herpes simplex virus (HSV) or vaccinia virus DNA in vitro. The rate of synthesis of DNA by nuclei from infected cells is up to 30 times higher than the synthesis of host DNA in vitro by nuclei isolated from uninfected HeLa cells. Thus HSV nuclei obtained from HSV-infected cells make DNA in vitro at a rate comparable to that seen in the intact, infected cell. Molecular hybridization studies showed that 80% of the DNA sequences synthesized in vitro by nuclei from herpesvirus-infected cells are herpesvirus specific. Vaccinia virus nuclei from vaccinia virus-infected cells, also produce comparable percentages of vaccinia virus-specific DNA sequences. Adenovirus nuclei from adenovirus 2-infected HeLa cells, which also synthesize viral DNA in vitro, have been included in this study. Synthesis of DNA by HSV or vaccinia virus nuclei is markedly inhibited by the corresponding viral-specific antisera. These antisera inhibit in a similar fashion the purified herpesvirus-induced or vaccinia virus-induced DNA polymerase isolated from infected cells. Phosphonoacetic acid, reported to be a specific inhibitor of herpesvirus formation and the herpesvirus-induced DNA polymerase, is equally effective as an inhibitor of HSV DNA synthesis in isolated nuclei in vitro. However, we also find phosphonoacetic acid to be an effective inhibitor of vaccinia virus nuclear DNA synthesis and the purified vaccinia virus-induced DNA polymerase. In addition, this compound shows significant inhibition of DNA synthesis in isolated nuclei obtained from adenovirus-infected or uninfected cells and is a potent inhibitor of HeLa cell DNA polymerase alpha.
Relationships among the polypeptides of Newcastle disease virus
Authors: Hightower L E , Morrison T G , Bratt M A
Published: January 2020

We have studied the relationships among the polypeptides of Newcastle disease virus by using both kinetic and tryptic peptide analyses. The results of our tryptic peptide analyses suggest that there are at least six unique viral polypeptides--L, HN, FO(F), NP, M, and a 47,000-dalton polypeptide. The small virion glycopolypeptide F is related to FO, a glycopolypeptide found only in infected cells. In addition, several smaller polypeptides, including a 53,000-dalton polypeptide found both in purified virions and in infected cells, are related to the nucleocaspid protein. Kinetic analysis of each viral polypeptide reveals that all of the major viral polypeptides, with the possible exception of L, are stable after an amino acid chase. A precursor-product relationship between FO and F was not demonstrable by pulse-chase experiments. Also, almost the same relative amount of F, the putative product, was present in infected cultures after either 5 or 30 min of radioisotopic labeling. These results suggest that FO is processed rapidly.
Nuclear polyhedrosis virus detection: relative capabilities of clones developed from Trichoplusia ni ovarian cell line TN-368 to serve as indicator cells in a plaque assay
Authors: Volkman L E , Summers M D
Published: January 2020

Cloned cell lines from the established Trichoplusia ni line TN-368 appear to differ from one another in their relative capabilities to serve as plaque assay indicator cell lines for Autographa californica nuclear polyhedrosis virus. Although there seems to be little correlation between their relative generation times and their efficiency in supporting plaque formation as indicator cell lines, there does seem to be a relationship within a given line between its capability to serve as an indicator and its phase of growth as a population; i.e., lag, logarithmic, or stationary. Both the parent line and clone 10 were more efficient indicators when they were in the logarithmic phase of growth than when in either the lag or stationary phases. Also, there appears to be a rough correlation between the capability of a given clone to serve as an indicator and the rate at which polyhedra first appear in the nuclei of the infected cells, with the best indicators producing polyhedra first. Increased incubation time has no effect on equalizing the plaque assay results for the less efficient clones. It was observed, also, that those clones that are the least efficient as plaque assay indicators produce the most external PFU per cell.
Adenovirus assembly: self-assembly of partially digested hexons
Authors: Boulanger P A
Published: January 2020

Papainic hydrolysis of adenovirus type 2 hexon capsomers was apparently limited and induced self-aggregation of hexons in a preferred oligomeric species, hexon trimers, sedimenting at about 19X, and retaining their immunological properties. These hexon trimers were composed of two classes of trimer molecules with different electric charges. The relevance of this trimer aggregation phenomenon to the adenovirus assembly process is discussed.
Inhibition of Cellular Protein Synthesis by Simultaneous Pretreatment of Host Cells with Fowl Plague Virus and Actinomycin D: a Method for Studying Early Protein Synthesis of Several RNA Viruses
Authors: Kaluza G. , Kraus A. A. , Rott R.
Published: January 2020

A method is described for analysis of viral protein synthesis early after infection when minute amounts of viral proteins are effectively concealed by large amounts of produced host-specific proteins. The method is superior to a radioimmune assay, since all virus-induced proteins can be measured independent of their immunological reactivity. Host-specific protein synthesis can be suppressed by infection with fowl plague virus. Addition of actinomycin D 1.25 h postinfection does not prevent this suppression, but it does block effectively the formation of fowl plague virus-specific proteins. Such cells synthesize only small amounts of cellular proteins, as revealed by polyacrylamide electrophoresis. They can be superinfected with several different enveloped viruses, however, without significant diminution of virus yields. In pretreated cells the eclipse is shortened for Semliki Forest virus, Sindbis virus, and vesicular stomatitis virus, but prolonged for Newcastle disease virus. The onset of protein synthesis, specific for the superinfecting virus, could be clearly demonstrated within 1 h after superinfection. At this time, in cells superinfected with Semliki Forest virus, great amounts of NSP 78 (nonstructural protein; molecular weight, 78 × 10
3
) and reduced amounts of the core protein C could be demonstrated. The precursor glycoprotein NSP 68 is followed by a new polypeptide, NSP 65; three proteins with molecular weights exceeding 100 × 10
3
were observed which are missing later in the infectious cycle. Similar results were obtained after superinfection with Sindbis virus. The formation of a new polypeptide with a molecular weight of about 80 × 10
3
was detected. After superinfection with vesicular stomatitis virus or Newcastle disease virus the formation of new proteins, characteristic for the early stage of infection, was not observed.
DNA-Minus Temperature-Sensitive Mutants of Adenovirus Type 5 Help Adenovirus-Associated Virus Replication
Authors: Straus Stephen E. , Ginsberg Harold S. , Rose James A.
Published: January 2020

Efficient potentiation of adenovirus-associated viruses (AAV) replication occurs in coinfections with either of two DNA-minus temperature-sensitive mutants of adenovirus type 5 (Ad5), ts125 and ts149. The helper activity of these mutants does not result from leakiness. At the nonpermissive temperature (39.5 C) there was little or no detectable adenovirus DNA synthesis, and only a relatively low level of adenovirus transcription was observed. However, the synthesis of AAV DNA and RNA and the yield of infectious AAV were comparable in amounts to those found when wild-type Ad5 was the helper. Furthermore, an apparent lag in the initiation of AAV transcription after the onset of AAV DNA synthesis was seen in coinfections with both wild type or ts125. These findings strongly suggest that the adenovirus factor(s) required for AAV multiplication is produced early in the adenovirus cycle. In addition, it is likely that if AAV multiplication is linked to adenovirus DNA replication, this requirement does not include all factors directly needed for adenovirus DNA synthesis.
Studies on Morphological Transformation of BALB/3T3-Derived Clones by Murine Leukemia Virus
Authors: Smith Helene S. , Hackett Adeline J. , Springer E. Louise , Riggs John
Published: January 2020

We have described a cell line, UC1-B, derived spontaneously from BALB/3T3 mouse embryo cells, which, unlike the standard BALB/3T3, are morphologically transformed and produce bizarre viral forms in response to murine leukemia virus. Although UC1-B and BALB/3T3 are morphologically similar, and both form contact-inhibited monolayers at confluence, the UC1-B cells are partially transformed because: they grow to a slightly higher saturation density than 3T3 cells, they grow in medium lacking serum growth factors, and they produce tumors in mice. Another clone, 12A-3, derived from BALB/3T3, also transforms and produces bizarre viral forms after infection with murine leukemia virus. Unlike UC1-B cells, the 12A3-8 cells are identical in growth properties to BALB/3T3; therefore, a partially altered morphology is not required for the induction of transformation by murine leukemia virus.
Lack of infectivity of the endogenous avian leukosis virus-related genes in the DNA of uninfected chicken cells
Authors: Cooper G M , Temin H M
Published: January 2020

The infectivity of the avian leukosis virus-related genes in the DNA of four genetically distinct types of chicken cells was determined. Infectious DNA of Rous-associated virus-O(RAV-O) was obtained from V- chicken cells which were experimentally infected with RAV-O and from V+tvbs chicken cells, which spontaneously produced RAV-O and were sensitive to exogenous RAV-O infection. However, infectious DNA of RAV-O was not obtained from uninfected V- chicken cells or from V+tvbr chicken cells, which spontaneously produced a low titer of RAV-O but were resistant to exogenous RAV-O infection. No detectable amplification of the RAV-O related DNA sequences in the V+tvbs cells was found by hybridization of RAV-O 125I-labeled RNA to the DNAs of V+tvbs and uninfected V- cells. These results indicate that the endogenous avian leukosis virus-related genes in uninfected V- and V+tvbr cells differ from the RAV-O proviruses in RAV-O-infected V- and V+tvbs cells. The lack of infectivity of the DNA of V+tvbr cells is consistent with the hypothesis that the endogenous RAV-O genome in V+tvbr cells is linked to a cis-acting control element, which results in its inefficient expression.
Genetic analysis of adenovirus type 2 III. Temperature sensitivity of processing viral proteins
Authors: Weber J
Published: January 2020

Using sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis of [35S]methionine-labeled adenovirus type 2-infected KB cell extracts, a total of 23 virus-induced polypeptides was detected. This technique was applied to the analysis of the temperature-sensitive mutant, ts 1, which has previously been shown to be defective in a late function. By means of pulse-chase experiments, ts 1 was shown to be defective in the processing of the precursor polypeptide (Pre VII) to the major core protein VII. Two other putative precursor polypeptides, Va (27K) and Vb (24K), were also not processed. Thus, the ts 1 mutation blocked the appearance of six post-translational clevage products, i. e., polypeptides VI, VII, VIII, X, XI, and XII. All of these polypeptides are virion components. Processing was temperature sensitive in a shift-up experiment, whereas it was normal in a shift-down experiment. The kinetics of the temperature-shift experiments suggested that infectious virus could be recovered if enough time is provided for processing to take place. Processing was not inhibited by cycloheximide. The analysis of purified virus particles and empty shells (TCs) revealed the presence of the precursor and putative precursor polypeptides Pre-VII, Va and Vb, instead of their cleavage products, in both types of particles. Based on these results we propose that the ts 1 gene codes for or regulates an endoprotease which is responsible for the completion of the last step in virus maturation, that is, the conversion of "young virions" into mature infectious virions by a series of maturation cleavages.
High-titer replication of nondefective Sendai virus in MDBK cells
Authors: Famulari N G , Fleissner E
Published: January 2020

Egg-grown Sendai virus was adapted to growth in a bovine kidney cell line (MDBK cells) by serial passage under defined conditions. The adapted virus contained only 50S RNA and was highly infectious for MDBK cells. Infection of these cells with a high multiplicity of adapted virus resulted in a yield of 10(8) MDBK-infectious units/ml by 18 h, accompanied by severe cytopathic changes in the host. Cell fusion did not occur. Examination of the proteins of the adapted virus revealed that despite the high infectivity of this virus for MDBK cells the virions contained considerable quantities of Fo, the precursor to the F glycoprotein that is responsible for cell fusion and high infectivity in other systems.
Purification and properties of bacteriophage phi X 174 gene D product
Authors: Farber M B
Published: January 2020

Bacteriophage phi X 174 gene D product, a protein required for single-stranded DNA synthesis by the phage, has been purified to near homogeneity. The protein is very abundant; approximately 10(5) monomers are present per infected cell when lysis is delayed. The protein has a monomer molecular weight of 15,200 and is normally a tetramer; however, it can form very large aggregates at high concentrations. Amino acid analysis shows an excess of arginine over lysine and a relatively high number of nonpolar residues. The protein carries a net negative charge at neutral pH. The first eight amino acids of the protein sequence have been determined; they are Ser-Gln-Val-Thr-Glu-Gln-Arg-Val. The carboxy-terminal residue is methionine. The protein has not yet been shown to bind directly to any single-stranded DNA; it does not adsorb to denatured calf thymus DNA-cellulose.
Herpesvirus proteins: induction of nucleoside phosphotransferase activity after herpes simplex virus infection
Authors: Jamieson A T , Hay J , Subak-Sharpe J H
Published: January 2020

After herpes simplex virus infection of hamster kidney cells there is an induction of nucleoside phosphotransferase activity which can utilize AMP as phosphate donor. The activity is immunologically specific for the infected cell and is induced concomitantly with the virus-coded pyrimidine deoxynucleoside kinase activity. Phosphotransferase activity is not induced in cells lacking both thymidine and deoxycytidine kinase activity.
Mutants of bacteriophage T4 deficient in the ability to induce nuclear disruption: shutoff of host DNA and protein synthesis gene dosage experiments, identification of a restrictive host, and possible biological significance
Authors: Snustad D P , Bursch C J , Parson K A , Hefeneider S H
Published: January 2020

The shutoff of host DNA synthesis is delayed until about 8 to 10 min after infection when Escherichia coli B/5 cells were infected with bacteriophage T4 mutants deficient in the ability to induce nuclear disruption (ndd mutants). The host DNA synthesized after infection with ndd mutants is stable in the absence of T4 endonucleases II and IV, but is unstable in the presence of these nucleases. Host protein synthesis, as indicated by the inducibility of beta-galactosidase and sodium dodecyl sulfate-polyacrylamide gel patterns of isoptopically labeled proteins synthesize after infection, is shut off normally in ndd-infected cells, even in the absence of host DNA degradation. The Cal Tech wild-type strain of E. coli CT447 was found to restrict growth of the ndd mutants. Since T4D+ also has a very low efficiency of plating on CT447, we have isolated a nitrosoguanidine-induced derivative of CT447 which yields a high T4D+ efficiency of plating while still restricting the ndd mutants. Using this derivative, CT447 T4 plq+ (for T4 plaque+), we have shown that hos DNA degradation and shutoff of host DNA synthesis occur after infection with either ndd98 X 5 (shutoff delayed) or T4D+ (shutoff normal) with approximately the same kinetics as in E. coli strain B/5. Nuclear disruption occurs after infection of CT447 with ndd+ phage, but not after infection with ndd- phage. The rate of DNA synthesis after infection of CT447 T4 plq+ with ndd98 X 5 is about 75% of the rate observed after infection with T4D+ while the burst size of ndd98 X 5 is only 3.5% of that of T4D+. The results of gene dosage experiments using the ndd restrictive host C5447 suggest that the ndd gene product is required in stoichiometric amounts. The observation by thin-section electron microscopy of two distinct pools of DNA, one apparently phage DNA and the other host DNA, in cells infected with nuclear disruption may be a compartmentalization mechanism which separates the pathways of host DNA degradation and phage DNA biosynthesis.
Differential inhibition of host protein synthesis in L cells infected with RNA - temperature-sensitive mutants of vesicular stomatitis virus
Authors: McAllister P E , Wagner R R
Published: January 2020

The response of mouse L cells to infection with wild-type (wt) and temperature-sensitive (ts) mutants of vesicular stomatitis virus was monitored by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to delineate the synthesis of host cell and viral proteins. Experiments utilized transcriptase mutants of complementation group I (ts114 and ts13), a group IV mutant (ts44) that is restricted in total RNA synthesis (RNA-1) but not in primary transcription, and a group II mutant (ts52) variably restricted in RNA synthesis (RNA +/-). L cells infected with ts mutants at permissive temperature exhibited the wt response of progressive inhibition of host cell protein synthesis accompanied by accumulation of all five viral proteins. Mutant ts44 (IV) also switched off cell protein synthesis at restrictive temperature and accumulated all five viral proteins, but with disproportionate ratios of N and G proteins. At restrictive temperature, cells infected with group I ts mutants failed to accumulate any viral protein and did not exhibit significant reduction in host cell protein synthesis. These data suggest that vesicular stomatitis virus inhibits cell protein synthesis at a stage of viral infection after transcription and possibly translation but preceding replication of progeny viral RNA.
Construction and analysis of viable deletion mutants of simian virus 40
Authors: Shenk T E , Carbon J , Berg P
Published: January 2020

Viable mutants of simian virus 40 (SV40), with deletions ranging in size from 15 to 200 base pairs, have been obtained by infecting CV-1P cells with circularly permuted linear SV40 DNA. The linear DNA was produced by cleavage of closed circular DNA with DNase I in the presence of Mn2+, followed, in some cases, by mild digestion with lambda 5'-exonuclease. The SV40 map location and the size of each deletion were determined by using the S1 nuclease mapping procedure (Shenk et al., 1975) and the change in size of fragments produced by Hind II + III endonuclease cleavage. Deletions in at least three regions of the SV40 chromosome have slight or no effect on the rate or yield of viral multiplication and on vira-induced cellular transformation. These regions are located at the following coordinates on the SV40 physical map: 0.17 to 0.18; 0.54 to 0.59; and 0.68 to 0.74.
Localization and functional role of the pseudomonas bacteriophage 2 depolymerase
Authors: Castillo F J , Bartell P F
Published: January 2020

The adsorption apparatus of phage 2 consits of a symmetrical base plate of snowflake appearance, composed of six droplike spikes 7.0 to 7.5 nm in length with a maximum diameter of 4.5 to 5.0 nm. The spikes are attached by their narrow ends to a central ring 7.0 to 7.5 nm in diameter. Phage 2 deopolymerase, a phage 2-induced hydrolytic enzyme, was found to be a structural protein of phage 2 or in close association with the base plate. Pdp1, a phage 2 mutant, possesses a polypeptide that is antigenically similar to the depolymerase, but devoid of hydrolytic activity. This polypeptide was found to be located in the region of the base plate of pdp1. Treatment of intact cells of strain BI with purified phage 2 depolymerase inhibited the adsorption of phage 2. When phage receptor-containing fractions of slime glycolipoprotein and lipopolysaccharide were hydrolyzed by the depolymerase, amino sugars were released, and the phage-inactivating activities of these fractions were lost. The depolymerase was also observed to induce the lysis of strain BI cells in hypotenic medium. The phage 2 depolymerase appears to play a role in adsorption and release of phage.