bluuebunny/crossref_metadata_2025 huggingface dataset:
T-antigen expression in proliferating and non-proliferating simian virus 40-transformed mouse cells
Authors: Zouzias D , Basilico C
Published: January 2020

Previous studies with simian virus 40-transformed mouse 3T3 cells which are temperature sensitive for the expression of the transformed phenotype (ts SV3T3 cells) have shown that T-antigen expression and viral DNA transcription are under cell cycle control. Using these ts SV3T3 cells, we studied the expression of the viral genome under proliferating and non-proliferating conditions, in the presence and absence of inhibitors of macromolecular synthesis and of the tumor promoter phorbol myristate acetate. ts SV3TE cells which are growth arrested at 39 degrees C by low serum concentration or saturation density accumulated in G1 and did not express T-antigen. When these cells were induced to proliferate, at either 32 or 39 degrees C, T-antigen synthesis preceded the entry of the cells into the S-phase and was not coupled to DNA replication. G1-arrested ts SV3T3 cells were induced to synthesize T-antigen by phorbol myristate acetate treatment, but T-antigen alone was not sufficient to induce cellular DNA synthesis. Isoleucine deprivation arrested growth of ts SV3T3 cells, but these cells, as well as normal 3T3, did not accumulate in G1 and continued to express T-antigen. The temperature-sensitive expression of the transformed phenotype in the ts SV3T3 cells does not appear to be due to a lack of transcription of specific regions of the integrated simian virus 40 genome at 39 degrees C.
Spleen focus-forming Friend virus: identification of genomic RNA and its relationship to helper virus RNA
Authors: Evans L H , Duesberg P H , Troxler D H , Scolnick E M
Published: January 2020

The genome of the defective, murine spleen focus-forming Friend virus (SFFV) was identified as a 50S RNA complex consisting of 32S RNA monomers. Electrophoretic mobility and the molecular weights of unique RNase T1-resistant oligonucleotides (T1-oligonucleotides) indicated that the 32S RNA had a complexity of about 7.4 kilobases. Hybridization with DNA complementary to Friend murine leukemia virus (Fr-MLV) has distinguished two sets of nucleotide sequences in 32S SFFV RNA, 74% which were Fr-MLV related and 26% which were SFFV specific. By the same method, SFFV RNA was 48% related to Moloney MLV. We have resolved 23 large T1-oligonucleotides of SFFV RNA and 43 of Fr-MLV RNA. On the basis of the relationship between SFFV and Fr-MLV RNAs, the 23 SFFV oligonucleotides fell into four classes: (i) seven which had homologous equivalents in Fr-MLV RNA; (ii) six more which could be isolated from SFFV RNA-Fr-MLV cDNA hybrids treated with RNases A and T1; (iii) eight more which were isolated from hybrids treated with RNases A and T1; and (iv) two which did not have Fr-MLV-related counterparts. Surprisingly, the two class iv oligonucleotides had homologous counterparts in the RNA of six amphotropic MLV's including mink cell focus-forming and HIX-MLVs analyzed previously. The map locations of the 23 SFFV T1-oligonucleotides relative to the 3' polyadenylic acid coordinate of SFFV RNA were deduced from the size of the smallest polyadenylic acid-tagged RNA fragment from which a given oligonucleotide was isolated. The resulting oligonucleotide map could be divided roughly into three segments: two terminal segments which are mosaics of oligonucleotides of classes i, ii, and iii and an internal segment between 2 and 2.5 kilobases from the 3' end containing the two oligonucleotides shared with amphotropic MLVs. Since SFFV RNA consists predominantly of sequence elements related to ecotropic and amphotropic helper-independent MLVs, it would appear that the transforming gene of SFFV is not a major specific sequence unrelated to genes of helper viruses, as is the case with Rous sarcoma and probably withe other defective sarcoma and acute leukemia viruses.
Virus production and hemoglobin synthesis in variant lines of dimethyl sulfoxide-treated Friend erythroleukemia cells
Authors: Tsuei D , Haubenstock H , Revoltella R , Friend C
Published: January 2020

Variant Friend erythroleukemia cell clones were compared in regard to their response to dimethyl sulfoxide and in their abilities to synthesize virus and hemoglobin. Clear evidence was obtained that cellular growth is required for virus production. The effects of dimethyl sulfoxide on virus production were not observed in cell lines that were resistant to growth perturbation by the compound. Studies of cell variants that were defective in either hemoglobin or virus synthesis indicate that these activities are independently regulated.
Genetic Analysis of a Baculovirus,
Autographa californica
Nuclear Polyhedrosis Virus I. Isolation of Temperature-Sensitive Mutants and Assortment into Complementation Groups
Authors: Brown Martha , Crawford Allan M. , Faulkner Peter
Published: January 2020

Temperature-sensitive (
ts
) mutants were isolated from the baculovirus
Autographa californica
(alfalfa looper)
M
NPV, grown in
Spodoptera frugiperda
(fall armyworm) cells in the presence of
N
-methyl-
N′
-nitro-
N
-nitrosoguanidine. Of 567 plaque isolates screened, 27 were temperature sensitive (
ts
), representing a mutation frequency of 4.8%. Ten
ts
mutants were studied in detail: six failed to yield nonoccluded virus at 33°C (
NOV
mutants), whereas the other four produced nonoccluded virus but were restricted in formation of polyhedra at 33°C (
Poly
mutants). One of the six
NOV
mutants failed to synthesize viral DNA. Reversion and leak frequencies were determined, and the mutants were assorted into complementation groups based on the yield of polyhedrin synthesis in cells coinfected with pairs of mutants at 33°C, as measured by radioimmunoassay. For
NOV
mutants, complementation indexes were also based on virus yield and were consistent with those based on polyhedrin synthesis. Nine mutants were assorted into five complementation groups. One mutant remained unclassified.
Is abortive infection by bacteriophage BF23 of Escherichia coli harboring ColIb plasmids due to cell killing by internally liberated colicin Ib?
Authors: McCorquodale D J , Shaw A R , Moody E E , Hull R A , Morgan A F
Published: January 2020

Infection of Escherichia coli harboring ColIb+ plasmids with bacteriophage BF23+ is abortive and resulted in changes of membrane permeability as measured by efflux of nucleotides and K+. A single pre-early gene product of BF23+ was necessary and sufficient to elicit the abortive response. Appropriate mutations in this pre-early gene allowed a productive infection in ColIb+ cells. Appropriate mutations in the ColIb plasmid also allowed a productive infection with BF23+. A comparison of changes occurring during abortive infection and during killing of sensitive cells by external colicin Ib or Ia, together with certain genetic data, has led to the conclusion that membrane changes accompanying the two phenomena are the result of a common mechanism, namely, the interaction of free colicin with the cytoplasmic membrane.
Regulation of Simian Virus 40 Transcription: Sensitive Analysis of the RNA Species Present Early in Infections by Virus or Viral DNA
Authors: Parker Barbara A. , Stark George R.
Published: January 2020

We have examined the discrete species of simian virus 40 (SV40) RNA present very early in infection of monkey cells with wild-type virus, with mutant
tsA
58 virus, and with the corresponding DNAs to distinguish between two classes of models for control of late transcription: (i) positive control mediated by large-T antigen and (ii) negative control mediated by a repressor protein associated with viral DNA in the virion. Total cytoplasmic or nuclear polyadenylated RNAs from infected cells were denatured with glyoxal, separated by electrophoresis on agarose gels, and transferred to diazobenzyloxymethyl paper. The positions of specific early and late RNA species were determined with region-specific SV40 DNA probes. The technique can detect individual RNAs present at the level of less than one copy per cell. After 9.5 h at 37°C, appreciable amounts of two early RNAs (2.6 kilobases [kb] and 2.9 kb) were present in the cytoplasm of cells infected with wild-type virus or DNA, along with much smaller amounts of two late RNAs, 1.6 kb (16S) and 2.5 kb (19S). The amounts of the late RNAs were reduced, but they were still synthesized in the presence of cytosine arabinoside, an inhibitor of DNA synthesis. In comparable infections with
tsA
58 virus or DNA at nonpermissive temperature (41°C), substantial amounts of the two early RNAs were again present, but the two late RNAs could not be detected. However, small amounts of the late RNAs were found when infections with
tsA
58 virus or DNA were prolonged to 30 h at 41°C. These results are not consistent with negative control of late transcription through the action of a repressor and, taken together with other data, suggest that T antigen has an active role in late RNA synthesis. Specific early and late viral RNAs were also detected in the nuclear poly(A)
+
fractions and were similar in size to the RNA species found in the cytoplasmic polyadenylated fractions. The late nuclear RNAs (1.8 and 2.9 kb) were significantly larger than the late cytoplasmic species, possibly because they are precursors. The 2.6- and 2.9-kb early RNAs found in the cytoplasm are probably the messengers for large-T and small-t antigens, respectively.
Structural analysis of the genomes of gibbon ape and woolly monkey leukosis viruses
Authors: Sahagan B G , Haseltine W A
Published: January 2020

Infectious retroviruses have been isolated from gibbon apes and a woolly monkey. Previous studies have shown that these isolates share some antigenic determinants and that they exhibit partial nucleic acid homology. To further define the relationships in this group of viruses, we compared the RNAs of the viruses of the woolly monkey-gibbon ape class by two-dimensional polyacrylamide gel electrophoresis of the large RNase T1-resistant oligonucleotides. The degree of sequence identity between the RNAs was determined by the similarity of the fingerprint patterns and in some cases by partial sequence analysis of individual oligonucleotides. This technique permitted us to determine the degree of sequence identity in related RNA species. These studies showed that as much as 80% of the genomes of gibbon ape leukosis virus-Halls' Island and gibbon ape leukosis virus-brain could be identical. The other viruses, simian sarcoma-associated virus, gibbon ape leukosis virus-Thailand, and gibbon ape leukosis virus-San Francisco, showed an extensive but somewhat lower degree of sequence identity (between 40 to 60% of the genomes.
Mutant of B-tropic murine leukemia virus synthesizing an altered polymerase molecule
Authors: Gerwin B I , Rein A , Levin J G , Bassin R H , Benjers B M , Kashmiri S V , Hopkins D , O'Neill B J
Published: January 2020

A nonconditional mutant of B-tropic murine leukemia virus (MuLV), defective in polymerase, has been isolated by cloning chronically infected cells. The cell clone containing the mutant produced virus particles which were noninfectious. However, superinfection of the cells by replication-competent XC-negative viruses resulted in the rescue of virus capable of forming plaques in a modified XC test, termed the "complementation plaque assay" (A. Rein and R. H. Bassin, J. Virol. 28:656-660, 1978). Analysis of the noninfectious virions produced without superinfection demonstrated that they contained only 2 to 5% of the wild-type level of reverse transcriptase activity. Purification of this activity indicated that it was associated with a smaller molecule than that produced by wild-type virus. Cells producing the mutant virions did not contain the gag-pol precursor, Pr180gag-pol; however the cells contained proteins of 147K and 114K daltons precipitable with anti-pol serum. All of the normal structural proteins as well as 70S genomic RNA could be detected in the mutant particles. An interference test indicated that a functional ecotropic glycoprotein was synthesized by the mutant. These results indicate that the mutant has a unique defect in the pol gene.
Simian rotavirus SA11 replication in cell cultures
Authors: Estes M K , Graham D Y , Gerba C P , Smith E M
Published: January 2020

Understanding the basic virology of rotavirus infections has been hampered by the fastidiousness of most isolates and by the lack of a rapid quantitative assay method. The growth characteristics of the simian rotavirus SA11 were studied because it grows to high titers in tissue culture and infectivity can be quantitated by plaque assay. SA11 replication was analyzed in a variety of primary cell cultures or continuous cell lines derived from both homologous and heterologous hosts. Viral replication was observed in each of the cell cultured examined. The individual cell cultures demonstrated marked variability in their susceptibility to rotavirus infection. The highest titers were obtained with MA104, BSC-1, CV-1, and BGM cells. Observable cytopathic effect was found to correlate with the percentage of infected cells in the culture. This study presents growth curves of the simian rotavirus in a variety of cell cultures.
Heat-sensitive lambda repressors retain partial activity during bacteriophage induction
Authors: Lieb M
Published: January 2020

At 43 degrees C, lambda cIts prophages are "induced" and enter the lytic cycle. Lac- lysogens containing heat-inducible lambda N- prophages were superinfected with a lambda trp/lac N+cI- phage containing a lacZ+ gene whose expression is controlled by the lambda cI product (repressor). Lysogens were then heated, and the synthesis of beta-galactosidase and release of progeny phage were measured. In lambda N- cIts2 or lambda N-cIts16 lysogens superinfected with lambda trp/lac N+, beta-galactosidase appeared earlier and was synthesized more rapidly than in superinfected lysogens containing lambda N- cIts857 prophage. Even at 45 degrees C, the cI857 repressor retained some activity. Lysogens containing other N-cIts mutant prophages producing renaturable repressors were also only partially derepressed at 43 degrees C. Partial derepression of lambda "early" transcription is sufficient for induction of lambda N+ prophages.
Apparent posttranscriptional block to anaerobic induction of endogenous leukemia virus
Authors: Whitaker-Dowling P A , Marotti K R , Anderson G R
Published: January 2020

Uninfected Fischer rat cells were induced by anaerobic stress to transcribe high levels of endogenous type C leukemia virus RNA. Complete 35S virus RNA with attached polyadenylic acid sequences was found associated with polysomes, indicating functional mRNA. Since no mature virus was released under these conditions, the presence of a posttranscriptional block to complete virus synthesis is strongly indicated.
Structure and function of adenovirus type 12 defective virions
Authors: Mak I , Ezoe H , Mak S
Published: January 2020

Purified human adenovirus type 12 preparations contain defective virions with a lighter density. These defective virions were isolated, and their biological functions and DNA were characterized. They can induce early and late antigens in infected cells and tumors in newborn hamsters with similar efficiency as complete virions. The majority of the DNA molecules from light virions contain deletions mapping near 16% from the left-hand end of the genome. Mechanisms for the generation of these molecules are discussed.
Impaired Maturation of Mouse Mammary Tumor Virus Precursor Polypeptides in Lymphoid Leukemia Cells, Producing Intracytoplasmic A Particles and No Extracellular B-Type Virions
Authors: Nusse Roeland , van der Ploeg Lex , van Duijn Luuk , Michalides Rob , Hilgers Jo
Published: January 2020

Processing of polypeptides of the mouse mammary tumor virus, a type B retrovirus, was investigated in a transplanted thymic lymphoma cell line of the GR strain (GRSL). This cell line was maintained in vivo in ascites form and in vitro as a suspension culture. GRSL cells produce clusters of intracytoplasmic A particles and are virtually deficient in the production of mature extracellular B-type particles. As control, a mammary tumor cell line of the same mouse strain capable of complete virion synthesis was used. The kinetics of viral polypeptide synthesis were studied by pulse labeling with various isotopes (including
35
S and
32
P), followed by immunoprecipitation of cell lysates with monospecific antisera to the major mouse mammary tumor virus
gag
and
env
proteins, p27 and gp52, respectively. Both the primary
gag
and
env
precursor polypeptides were synthesized in the GRSL cells, but their conversion into viral proteins was impaired. The major
gag
precursor, Pr73

gag

, was stable over a period of 8 h, and mature viral core polypeptides could not be detected. Also, the highly phosphorylated intermediates in the proteolytic processing of Pr73

gag

in virus-producing cells were absent in GRSL cells. By immunoprecipitation, Pr73

gag

was detected in a GRSL particle fraction with the density of intracytoplasmic A particles. The precursor for envelope proteins, Pr73

env

, was turned over without the generation of mature viral envelope components gp52 and gp36. The in vivo-transplanted ascites GRSL cells, however, were shown to express gp52 on the cell surface together with a 73,000-dalton polypeptide, as indicated by cell surface iodination and immunoprecipitation.
Serological relationship of woodchuck hepatitis virus to human hepatitis B virus
Authors: Werner B G , Smolec J M , Snyder R , Summers J
Published: January 2020

Two antigenic systems of the woodchuck hepatitis virus have been identified. The relationship between viral antigens of the woodchuck hepatitis virus and the human hepatitis B virus was determined by using immunoprecipitation, hemagglutination, and immune electron microscopy techniques. Antigens found on the cores of the two viruses were cross-reactive. Lack of cross-reactivity between the surface antigens of the two viruses in immunodiffusion experiments suggested that the major antigenic determinants of the viral surfaces are different; however, results of passive hemagglutination tests indicated that there are common minor determinants. Nucleic acid homology, as measured by liquid hybridization, was found to be 3 to 5% of the viral genomes. The results of this study provide further evidence that woodchuck hepatitis virus is the second member of a new class of viruses represented by human hepatitis B virus. Since virus-infected woodchucks may acquire chronic hepatitis and hepatocellular carcinoma, these antigens and their respective antibodies will be useful markers for following the course of virus infection in investigations of the oncogenic potential of this class of viruses. The nucleocapsid antigen described may be a class-specific antigen of these viruses and, thus, may be useful in discovering new members of the group.
Polymorphism of B-tropic leukemia viruses from BALB/c mice: association of a p30 antigen with N- versus B-tropism
Authors: Tress E , O'Donnell P V , Famulari N , Ellis R W , Fleissner E
Published: January 2020

Comparison of a number of murine leukemia virus clones by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed extensive protein polymorphism among B-tropic, but not N-tropic, isolates from BALB/c mice, particularly in migration of p30 proteins. A type-specific radioimmunoassay for p30 was developed which uniformly discriminated all B-tropic viruses from N-tropic viruses of BALB/c origin. N- and B-tropic viruses of C57BL/6 and AKR Fv-1b/b origin could also be distinguished by this assay.
Immune response to the src gene product in mice bearing tumors induced by injection of avian sarcoma virus-transformed mouse cells
Authors: Parsons S J , Riley S C , Mullen E E , Brock E J , Benjamin D C , Kuehl W M , Parsons J T
Published: January 2020

A single subcutaneous injection of 10(7) live cells of the highly tumorigenic avian sarcoma virus (Schmidt-Ruppin strain, subgroup D)-transformed BALB/c line into BALB/c mice resulted in the production of an antiserum specific for the avian sarcoma virus gene product pp60src. All sera taken from mice 3 weeks after injection of tumor cells contained antibodies to pp60src. Immunoprecipitation experiments showed that all sera precipitated pp60src from Schmidt-Ruppin-infected chicken cells, but only a portion of these sera precipitated pp60src from chicken cells infected with other strains of avian sarcoma virus, i.e., Prague and Bratislava-77. Analysis of the cross-reactivity patterns of these antisera demonstrated a minimum of three to four antigenic determinants on pp60src. The findings reported here should facilitate the production of monoclonal antibodies to pp60src, which in turn will provide highly specific probes for further investigations into the structure and function of this protein.
Two avian sarcoma virus mutants with defects in the DNA polymerase-RNase H complex
Authors: Moelling K , Friis R R
Published: January 2020

Two mutants of avian sarcoma virus which exhibit different phenotypes have been analyzed for the properties of their RNA-dependent DNA polymerase and RNase H activities. LA 338 is a complex multiple mutant with at least one lesioneach in transformation and replication functions. The purified RNA-dependent DNA polymerase-RNase H complex from the mutant is twofold more thermolabile than that from the wild-type parent. A peculiarity of this mutant is that the ability of the enzyme to respond to synthetic template-primers is lost more rapidly than is the response to native RNA as template. The mutant enzyme cannot be protected from inactivation by the addition of synthetic template-primers. LA 672 represents a different phenotype among reverse transciptase mutant, showing a "late"-acting block in replication which affects only production of progeny by infected cells grown at the nonpermissive temperature. The purified DNA polymerase-RNase H complex of LA 672 is not thermolabile; rather, progeny grown at the nonpermissive temperature yield purified enzyme with a 20-fold-reduced specific activity in both DNA polymerase and RNase H. The content of reverse transcriptase protein in such noninfectious progeny, furthermore, did not appear to be significantly diminished since immunologically active enzyme could be demonstrated in a competition test for anti-reverse transcriptase antibody and since beta and alpha subunits of reverse transcriptase could be identified after polyacrylamide gel electrophoresis of partially purified enzyme preparations. The amounts of beta and alpha from the mutant were about twofold lower.
Transforming DNA sequences in rat cells transformed by DNA fragments of highly oncogenic human adenovirus type 12
Authors: Sawada Y , Ojima S , Shimojo H , Shiroki K , Fujinaga K
Published: January 2020

Rat cell lines tranformed by viral DNA fragments, EcoRI-C and HindIII-G, of adenovirus type 12 DNA were analyzed for the viral transforming DNA sequences present in cell DNAs. Cell lines transformed by the EcoRI-C fragment of adenovirus type 12 DNA (leftmost 16.5% of the viral genome) contain most of the HindIII-G sequences of the HindIII-G fragment, but at a different frequency depending on the portions of the fragment. The sequence of the AccI-H fragment of adenovirus type 12 DNA (the left part of the HindIII-G; leftmost 4.5% of the viral genome) was detected dominantly in cells transformed by the HindIII-G fragment Southern blot analysis showed that viral DNA sequences are present at multiple integration sites in high-molecular-weight cell DNA from cells transformed by the EcoRI-C or HindIII-G fragment of adenovirus type 12 DNA. These results suggest that most of the HindIII-G sequences in cells transformed by the HindIII-G fragment are present as fragmented forms.
Unusual Modification of Bacteriophage Mu DNA
Authors: Hattman Stanley
Published: January 2020

Bacteriophage Mu DNA was labeled after induction in the presence of [2-
3
H]adenine or [8-
3
H]adenine. Both Mu
mom
+
·
dam
+
DNA and Mu
mom
−
·
dam
+
DNA have similar
N
6
-methyladenine (MeAde) contents, as well as similar frequencies of MeAde nearest neighbors. Both DNAs are sensitive to in vitro cleavage by R·
Dpn
I but resistant to cleavage by R·
Dpn
II. These results indicate that the
mom
+
protein does not alter the sequence specificity of the host
dam
+
methylase to produce MeAde at new sites. However, we have discovered a new modified base, denoted A
x
, in Mu
mom
+
·
dam
+
DNA; approximately 15% of the adenine residues are modified to A
x
. Although the precise nature of the modification is not yet defined, analysis by electrophoresis and chromatography indicates that the
N
6
-amino group is not the site of modification, and that the added moiety contains a free carboxyl group. A
x
is not present in Mu
mom
+
·
dam
+
or Mu
mom
−
·
dam
+
phage DNA or in cellular DNA from uninduced Mu
mom
+
·
dam
+
lysogens. These results suggest that expression of the
dam
+
and
mom
+
genes are required for the A
x
modification and that this modification is responsible for protecting Mu DNA against certain restriction nucleases. Mu
mom
+
·
dam
−
DNA and Mu
mom
−
·
dam
−
DNA contain a very low level of MeAde (ca. 1 MeAde per 5,000 adenine residues). Since the only nearest neighbor to MeAde appears to be cytosine, we suggest that the methylated sequence is 5′... C-A
*
-C... 3′ and that this methylation is mediated by the
Eco
K modification enzyme.
Organization of mouse mammary tumor virus-specific DNA endogenous to BALB/c mice
Authors: Cohen J C , Majors J E , Varmus H E
Published: January 2020

We used restriction endonucleases to prepare physical maps of the mouse mammary tumor virus (MMTV)-specific DNA endogenous to the BALB/c mouse strain. The mapping was facilitated by the DNA transfer procedure, using complementary DNAs specific for the whole and for the 3' terminus of MMTV RNA to detect fragments containing viral sequences. The strategies used for the arrangement of fragments into physical maps included sequential digestions with two or three enzymes; preparative isolation of EcoRI fragments containing viral sequences; and comparisons of virus-specific fragments derived from the DNA of several mouse strains. Most of the MMTV-related DNA in the BALB/c genome is organized into two units (II and III) which strongly resemble proviruses acquired upon horizontal infection with milk-borne strains of MMTV and other retroviruses. These units contain approximately 6.0 x 10(6) Mr of apparently uninterrupted viral sequences, they bear redundant sequences totaling at least 700 to 800 base pairs at their termini, and the terminal redundancies include sequences derived from the 3' end of MMTV RNA. Units II and III are closely related in that they share 12 of 14 recognition sites for endonucleases, but cellular sequences flanking units II and III are dissimilar by this criterion. The remainder of the MMTV-related DNA endogenous to BALB/c mice is found in a single subgenomic unit (unit I) with a complexity of ca. 2 x 10(6) Mr; the structure of this unit has not been further defined. These results support the hypotheses that endogenous proviruses have been acquired by infection of germinal tissues with MMTV. The physical maps are also useful for identifying the MMTV genomes endogenous to BALB/c mice in studies of the natural history of mammary tumorigenesis.
Construction and analysis of viable deletion mutants of polyoma virus
Authors: Magnusson G , Berg P
Published: January 2020

Viable mutants of polyoma with small deletions ranging in size from 2 to 75 base pairs were obtained by infecting 3T3 cells with polyoma DNA that had been cleaved once with HaeII endonuclease or with DNase-Mn2+ digestion. The HaeII endonuclease-cleaved DNA yielded mutants with deletions at map position 72--73, whereas the mutants generated by DNase I-Mn2+ digestion had deletions either at map position 72--73 or within the map coordinates 92 and 99. Both groups of mutants appeared to grow as well as wild-type virus in 3T3 cells. The deletions at map position 72--73 did not alter the virus's ability to transform rat cells. Hence, the region just to the early side of the origin of DNA replication is not essential for vegetative growth or transformation. But the mutants with deletions in the region between map coordinates 92 and 99, a segment thought to code for polyoma large and middle T antigens (Hutchinson et al., Cell 15:65--77, 1978; Smart and Ito, Cell 15:1427--1437, 1978; Soeda et al., Cell 17:357--370, 1979), transformed rat cells at 0.2 to 0.05 the efficiency of wild-type virus.
Hormonal regulation of murine mammary tumor virus RNA expression during mammary tumorigenesis in BALB/c mice
Authors: Pauley R J , Medina D , Socher S H
Published: January 2020

The effects of glucocorticoids and prolactin on murine mammary tumor virus (MuMTV) RNA expression in preneoplastic outgrowth lines and mammary tumors in BALB/c mice were investigated. Hyperplastic alveolar nodules (HAN) and a ductal hyperplasia (DH) are induced in virgin BALB/c mice by prolonged hormonal stimulation or treatment with 7,12-dimethylbenz(a)anthracene or both. Mice bearing HAN or DH outgrowth lines and mammary tumors that arose from the outgrowth lines were treated with glucocorticoids or prolactin. MuMTV RNA was quantitated by hybridization with a representative complementary DNA probe specific for MuMTV RNA. Prolactin treatment did not increase MuMTV RNA in the BALB/c HAN or DH outgrowth lines or tumors. MuMTV RNA increased after glucocorticoid treatment in the C3, C4, and C5 HAN outgrowth lines and in tumors that arose from the D1, D2, C4, and C5 HAN and CD8 DH outgrowth lines. No increase in MuMTV RNA with glucocorticoid treatment was observed in the D1 or D2 HAN outgrowth line, in the CD8 DH outgrowth lines, and in tumors that arose from the C3 HAN outgrowth line. The ability of glucocorticoids to stimulate MuMTV expression was specific since the response was dose dependent and specific for glucocorticoid hormones. Glucocorticoid treatment did not increase the level of type C viral RNA in the majority of hormone- or 7,12-dimethylbenz(a)anthracene-induced HAN outgrowth lines or tumors. These observations suggested that glucocorticoids may influence MuMTV expression during mammary tumorigenesis in BALB/c mice.
Deletion mutant of the Bratislava-77 strain of Rous sarcoma virus containing a fusion of the group-specific antigen and envelope genes
Authors: Dierks P M , Highfield P E , Parsons J T
Published: January 2020

The genetic compositions of two independently derived preparations of the Bratislava-77 strain (B77) of Rous sarcoma virus were analyzed after each was passaged seven or more times in duck embryo fibroblasts. RNase, T1-resistant oligonucleotide fingerprint analysis of virion RNA from both preparations of duck-passaged B77 revealed the presence of two large noncontiguous deletions. Approximately 75% of the RNAs contained a deletion which spans oligonucleotides 304 to 4 on the viral genome (about 3,500 nucleotides) and encompasses all of the B77 polymerase gene. More than 90% of the RNAs also contained a deletion which spans src-specific oligonucleotides 6 and 5(about 2,200 nucleotides) and is identical to the deletion observed in transformation-defective B77. Virion RNA from duck-passaged B77 also contained two oligonucleotides (D1 and D2) not observed in the RNA of B77 virus grown on chicken embryo fibroblasts. Analysis of the virion RNA of duck-passaged B77 by denaturing agarose gel electrophoresis revealed four major subunits with molecular weights of 3.40 x 10(6), 2.65 x 10(6), 2.25 x 10(6), and 1.55 x 10(6). Whereas the 3.40- and 2.65-megadalton (Mdal) RNA species comigrated with the nondefective and transformation-defective RNAs of B77 propagated on chicken embryo fibroblasts, no counterparts to the 2.25- and 1.55-Mdal RNAs were observed in the RNA of B77 grown on chicken embryo fibroblasts. Oligonucleotide fingerprint analysis of these RNA species revealed that the 2.65-Mdal RNA contains the src-specific deletion and that 2.25-Mdal RNA contains the polymerase region deletion; both of these deletions were observed in the 1.55-Mdal RNA, which was the major RNA subunit species detected in duck-passaged B77. The new oligonucleotides (D1 and D2) observed in the duck-passaged virus were present in the 2.25- and 1.55-Mdal RNA species in vitro and in vivo and directs the synthesis of a 130,000-dalton protein (p130). p130 contains antigenic determinants specific for p27 (gag gene) and gp85 (env gene) but does not contain sequences which cross-react with antisera directed against the alpha beta form of RNA-dependent DNA polymerase (pol gene). This RNA, therefore, is generated by a fusion of the gag and env genes of Rous sarcoma virus B77.
Inactivation of influenza and vesicular stomatitis virion RNA polymerase activities by photoreaction with 4'-substituted psoralens
Authors: Nakashima K , Chanda P K , Deutsch V , Banerjee A K , Shatkin A J
Published: January 2020

Irradiation of purified influenza virus and vesicular stomatitis virus (VSV) with long-wavelength UV light in the presence of 4'-substituted psoralens inactivated the virion-associated RNA polymerase activity. Inactivation was apparently due to psoralen modification of the viral genome RNAs, since cations that decrease psoralen binding to nucleic acids had a protective effect, and reconstitution of VSV RNA polymerase activity was inhibited by photoreaction of nucleoprotein cores but not by pretreatment of soluble fraction from dissociated virions. Partially inactivated viral particles synthesized reduced amounts of full-length RNA products in vitro without an increase in prematurely terminated transcripts. VSV leader RNA formation was relatively resistant to psoralen photoinactivation, and sequential transcription was maintained by photoreacted VSV. The all-or-none psoralen effect on virion-associated RNA polymerase activities may be due to a differential photosensitivity of promoter sites or to structural changes in modified viral genome RNAs that prevent formation of new mRNA chains.
Characterization of Cricket Paralysis Virus-Induced Polypeptides in
Drosophila
Cells
Authors: Moore Norman F. , Kearns Anne , Pullin Jim S. K.
Published: January 2020

Cricket paralysis virus purified from
Galleria mellonella
larvae was shown to be similar to virus purified from
Drosophila melanogaster
cells. Cricket paralysis virus contained three major structural polypeptides of similar molecular weight (around 30,000), had a buoyant density of 1.344 g/ml, and had a capsid diameter of 27 nm. Twenty virus-induced polypeptides could be detected in CrPV-infected
Drosophila
cells. Two major polypeptides found in the infected cells corresponded to two structural viral polypeptides (VP1 and VP3), whereas the third major intracellular polypeptide was the apparent precursor of the third viral structural polypeptide (VP2). Three of the primary virus-induced polypeptides had molecular weights of 144,000, 124,000, and 115,000. These and other polypeptides were chased into lower-molecular-weight proteins when excess cold methionine was added after a short [
35
S]methionine pulse. Although cricket paralysis virus has a number of characteristics in common with the mammalian enteroviruses, the extremely fast processing of high-molecular-weight polypeptides into viral proteins seems atypical. Also, no VP4 (8,000 to 10,000 molecular weight) has been found in the virus particles.
Temperature-sensitive mutants of Chandipura virus. I. Inter- and intragroup complementation
Authors: Gadkari D A , Pringle C R
Published: January 2020

Fifty temperature-sensitive (ts) mutants of Chandipura virus, a human rhabdovirus, have been classified into six complementation groups, designated ChI, ChII, ChII, ChIV, ChV, and ChVI and containing 44, 2, 1, 1, 1, and 1 mutants, respectively. Weak complementation was observed within group ChI, allowing the division of the group into subgroups ChIA and ChIB. Intragroup complementation was most extensive within subgroup ChIB, and one mutant in this subgroup complemented all but one (ts Ch598) of the mutants in group ChI. If ts Ch598 had been omitted from the analysis the number of complementation groups would have been increased to seven. Consequently, in circumstances where intragenic and intergenic complementation cannot be clearly distinguished, the number of complementation groups identified in rhabdoviruses could be overestimated. The identification of six complementation groups in three different rhabdoviruses need not imply the existence of an as yet unidentified sixth virus-specified polypeptide. The extensive intragroup complementation observed in Chandipura virus suggests that the functional form of one at least of the virion proteins of Chandipura virus is a multimer.
Effect of Fv-1 gene product on synthesis of linear and supercoiled viral DNA in cells infected with murine leukemia virus
Authors: Jolicoeur P , Rassart E
Published: January 2020

Levels of unintegrated viral DNA made in Fv-1b/b (SIM.R, JLS-V9) and Fv-1n/n (NIH/3T3) cell lines after infection with N- or B-tropic murine leukemia virus (MuLV) have been measured. Different forms of viral DNA were sedimented on neutral sucrose or ethidium bromide-cesium chloride density gradients and detected by hybridization with complementary DNA. It was found that the major viral DNA species made in Fv-1 permissive or resistant cells was sedimenting at 20S on neutral sucrose gradient. Levels of this 20S viral DNA species were not significantly different in both systems. However levels of closed circular (form I) viral DNA separated on ethidium bromide-cesium chloride gradients were found to be decreased in Fv-1 resistant cells. Various species of viral DNA were also analyzed by the agarose gel-DNA transfer procedure of Southern. The major viral DNA species was found to migrate as a double-stranded linear DNA of 5.7 x 10(6) daltons. The molecular weight of linear viral DNA molecules extracted from Fv-1 permissive or resistant cells appeared to be the same. Levels of this linear viral DNA were almost identical in both systems except in B-tropic MuLV-infected resistant NIH/3T3 cells in which a moderate decrease has been measured. Two closed circular viral DNA species were observed by this technique. Their levels were markedly decreased in Fv-1 resistant cells. Our results indicate that the Fv-1 restriction does not grossly affect the formation of linear double-stranded viral DNA, but prevents the accumulation of closed circular viral DNA. Therefore the Fv-1 gene product could allow the synthesis of a normal linear viral DNA but interfere with the formation of supercoiled viral DNA. Alternatively, it could promote the synthesis of a faulty linear viral DNA whose defect (yet undetected) would prevent its circularization. In any case, the Fv-1 restriction mechanism appears to occur before the integration event itself.
Capped and polyadenylated low-molecular-weight RNA synthesized by vaccinia virus in vitro
Authors: Paoletti E , Lipinskas B R , Panicali D
Published: January 2020

In the presence of ATP plus two other ribonucleoside triphosphates or in reactions containing all four ribonucleoside triphosphates and actinomycin D, vaccinia virus synthesizes in vitro discrete low-molecular-weight RNA molecules ranging in size from about 20 to several hundred bases. A novel feature of these small RNA molecules is that they are capped and methylated at the 5' terminus, containing both mGpppGm and mGpppAm type cap structures, and in addition these molecules are polyadenylated at the 3' terminus. Hybridization of these RNAs to restriction fragments derived from vaccinia virus DNA indicates a considerable degree of complexity, suggesting the presence of a large number of promoters throughout the genome. However, measurable sensitivity to pancreatic RNase of the 5' capped end of these RNAs while in hybrid form to the DNA suggests other possible roles for these small RNAs in vaccinia virus mRNA biogenesis.
Alternate Capping Mechanisms for Transcription of Spring Viremia of Carp Virus: Evidence for Independent mRNA Initiation
Authors: Gupta Kailash C. , Roy Polly
Published: January 2020

Two alternate mechanisms of mRNA capping for spring viremia of carp virus have been observed. Under normal reaction conditions, a ppG residue of the capping GTP is transferred to a pA moiety of the 5′ termini of mRNA transcripts. However, in reaction conditions where GppNHp is used instead of GTP, an alternate capping mechanism occurs whereby a pG residue of the capping GTP is transferred to a ppA moiety of the transcripts. The first mechanism is identical to that described previously for vesicular stomatitis virus (G. Abraham, D. P. Rhodes, and A. K. Banerjee, Nature [London]
255
:37-40, 1975; A. K. Banerjee, S. A. Moyer, and D. P. Rhodes, Virology
61
:547-558, 1974), and thus appears to be a conserved function during the evolution of rhabdoviruses. The alternate mechanism of capping indicates not only that capping can take place by two procedures, but also that the substrate termini have di- or triphosphate 5′ ends, indicating that they are probably independently initiated. An analog of ATP, AppNHp, has been found to completely inhibit the initiation of transcription by spring viremia of carp virus, suggesting that a cleavage between the β and γ phosphates of ATP is essential for the initiation of transcription. However, in the presence of GppNHp, uncapped (ppAp and pppAp), capped (GpppAp), and capped methylated (m7GpppAmpAp and GpppAmpAp) transcripts are detected. Size analyses of oligodeoxythymidylic acid-cellulose-bound transcripts resolved by formamide gel electrophoresis demonstrated that full-size mRNA transcripts are synthesized as well as larger RNA species. The presence of GppNHp and
S
-adenosylhomocysteine in reaction mixtures did not have any effect on the type of unmethylated transcription products. Our results favor a transcription model postulated previously (D. H. L. Bishop,
in
H. Fraenkel-Conrat and R. R. Wagner, ed.,
Comprehensive Virology
, vol. 10, Plenum Press, New York, 1977; D. H. L. Bishop and A. Flamand,
in
D. C. Burke and W. C. Russell, ed.,
Control Processes in Virus Multiplication
, Cambridge University Press, Cambridge, 1975; D. H. L. Bishop and M. S. Smith,
in
D. Nayak, ed.,
The Molecular Biology of Animal Viruses
, Marcel Dekker, New York, 1977; P. Roy and D. H. L. Bishop, J. Virol.
11
:487-501, 1973) in which mRNA synthesis is initiated independently; they do not support a model for transcripts being synthesized by plus-strand cleavage (A. K. Banerjee, G. Abraham, and R. J. Colonno, J. Gen. Virol.
34
:1-8, 1977; A. K. Banerjee, R. J. Colonno, D. Testa, and M. T. Franze-Fernandez,
in
B. M. J. Mahy and R. D. Barry, ed.,
Negative Strand Viruses and the Host Cells
, Academic Press, London, 1978).
Nature of the Sendai virus receptor: glycoprotein versus ganglioside
Authors: Wu P S , Ledeen R W , Udem S , Isaacson Y A
Published: January 2020

Gangliosides were compared with glycoproteins as potential receptors for Sendai virus by incorporating measured amounts of the glycoconjugates into lecithin-cholesterol liposomes and measuring binding by a hemagglutination assay with sheep erythrocytes. HeLa cell gangliosides showed no binding activity toward the virus up to 15 micrograms of sialic acid per 5 mumol of lecithin-cholesterol, whereas HeLa cell glycoproteins incorporated into similar liposomes caused avid virus binding below 1 microgram of sialic acid. These sialoglycoproteins could be separated from the bulk of cell proteins by multiple chloroform-methanol extractions. Purified rat brain gangliosides at a level of 120 micrograms of sialic acid in liposomes did not bind virus, whereas chloroform-methanol-extracted rat brain proteins caused only marginal binding. Bovine brain gangliosides differed slightly from the rat brain mixture in showing weak binding properties. Our results thus indicate that glycoproteins, rather than gangliosides, are the natural receptors for Sendai virus and that tissues differ as to the quantity of such protein receptors.
Heterogeneity of vesicular stomatitis virus particles: implications for virion assembly
Authors: Lodish H F , Porter M
Published: January 2020

Vesicular stomatitis virus (VSV) particles formed at early times after infection contain only one-third the amount of viral glycoportein (G protein), relative to the major internal structural proteins M and N, as is found in particles released later. These "early" particles also have a lower density in equilibrium sucrose gradients than do those formed later; however, the sedimentation velocity and specific infectivity of these two classes of particles are the same. VSV-infected cells also release virus-like particles which sediment considerably faster than authentic virions and contain a higher-than-normal proportion of the VSV G protein relative to internal VSV proteins. These particles have a reduced specific infectivity but a normal density in sucrose gradients. All classes of VSV virions contain a constant proportion of M and N polypeptides. The ratio of G protein to M or N protein, in contrast, can vary over a sixfold range; this implies that an interaction between a precise number of surface G proteins with either of the underlying M and N proteins is not a prerequisite for budding of infectious viral particles from the cell surface.
Immunological relationships of an endogenous guinea pig retrovirus with prototype mammalian type B and type D retroviruses
Authors: Dahlberg J E , Tronick S R , Aaronson S A
Published: January 2020

A retrovirus endogenous to guinea pig cells was earlier shown to be morphologically similar to type B and type D prototype retroviruses. Molecular hybridization techniques were used to show that guinea pig virus nucleotide sequences are endogenous to both domestic (Cavia porcellus) and indigenous (Cavia aperea) guinea pigs, but cannot be detected in the DNA of either other hystricomorph rodents or other mammals tested. Using radioimmunological techniques designed to detect interspecies relationships, the major internal polypeptide of guinea pig virus (p26) was shown to share three different sets of interspecies antigenic determinants with squirrel monkey retrovirus, viper retrovirus, and mouse mammary tumor virus. Thus, guinea pig virus appears to provide an evolutionary link between type B and D retroviruses.
Phosphonoacetic Acid Inhibition of Frog Virus 3 Replication
Authors: Elliott R. M. , Bateson A. , Kelly D. C.
Published: January 2020

Phosphonoacetic acid at concentrations above 200 μg/ml inhibited the replication of frog virus 3 in BHK cells. The inhibition of viral DNA replication observed in these cells was reversible and correlated with the inhibition of the virus-induced DNA polymerase activity in an in vitro assay. The synthesis of frog virus 3-induced late or γ polypeptides was also inhibited by phosphonoacetic acid, although the early (α and β) polypeptides were unaffected.
Gene K of bacteriophage phi X 174 codes for a nonessential protein
Authors: Tessman E S , Tessman I , Pollock T J
Published: January 2020

Gene K of phi X 174, which overlaps genes A, B, and C, was found to be nonessential, although possibly beneficial for the growth of the phage. Viable mutants of gene K made less than 4% of the normal amount of K protein as judged by quantitative fluorography of sodium dodecyl sulfate-polyacrylamide gels; compared with the wild-type phi X, K mutants had an identical latent period but a two- to threefold reduction in burst size.