bluuebunny/crossref_metadata_2025 huggingface dataset:
Interference Between Two Adeno-associated Satellite Viruses: a Three-Component System
Authors: Torikai K. , Mayor H. D.
Published: January 2020

Adenovirus-associated satellite viruses interfere with the replication of their helper adenoviruses. According to a previous report, this interference is not mediated by interferon. A three-component system comprising simian adenovirus SV15 and satellites types 1 and 4 was studied to determine whether satellite viruses also interfere with one another. Satellite type 1 interfered with the replication of type 4 and vice versa. The degree of interference was directly proportional to the dose of interfering satellite. The events leading to mutual satellite interference were operative during the first 12 hr of replication, the period associated with active synthesis of viral deoxyribonucleic acid.
Sindbis Virus-induced Viral Ribonucleic Acid Polymerase
Authors: Sreevalsan T. , Yin Fay Hoh
Published: January 2020

A cytoplasmic structure containing the viral ribonucleic acid (RNA) polymerase has been isolated by sucrose density centrifugation from cells infected with Sindbis virus. Uninfected cells did not contain any such structure. Preliminary experiments indicated that the structure may be associated with membranes. This structure incorporated
3
H-guanosine triphosphate in vitro in the absence of added template. The RNA synthesized in vitro by the enzyme consisted of single-stranded 40
S
RNA, the ribonuclease-resistant replicative form, and possibly the replicative intermediate form of viral RNA. The products formed in vitro by the enzyme are identical in sedimentation rates to those formed in the infected cells in vivo.
Pathology and Development of the Grasshopper Inclusion Body Virus in
Melanoplus sanguinipes
Authors: Henry J. E. , Nelson B. P. , Jutila J. W.
Published: January 2020

Grasshoppers,
Melanoplus sanguinipes
(F.), infected with the grasshopper inclusion body virus (GIBV) showed a general torpor, took longer to develop, and had abnormally high rates of mortality. Infection was found only in the fat body, and developing viruses and inclusion bodies were observed in the nuclei and cytoplasm of infected cells. Although the size of the inclusion bodies in cells varied at different stages of infection, the inclusion bodies appeared to grow during the infection. Electron microscopic investigations of viral replication showed that at about 8 days after inoculation presumptive viral particles had developed as buds or protrusions from precursor granular masses; thereafter, these particles underwent internal differentiation and were incorporated into developing inclusion bodies. The GIBV was similar to insect viruses in the genus
Vagoiavirus
Weiser and to pox viruses, particularly vaccinia.
RNase III cleaves vesicular stomatitis virus genome-length RNAs but fails to cleave viral mRNA's
Authors: Wertz G W , Davis N L
Published: January 2020

The procaryotic RNA processing enzyme RNase III (endoribonuclease III [EC 3.1.4.24]) was used to probe vesicular stomatitis virus (VSV) RNAs for specific sites that could be recognized and cleaved. The effect of the enzyme on the RNAs was monitored by measuring their subsequent migration in denaturing agarose-urea gels. VSV virion RNA (negative strand; Mr, 4 X 10(6)) was cleaved by the enzyme to yield a set of discrete fragments which ranged on size from 3.5 X 10(6) to 0.2 X 10(6) daltons. The cleavage was a function of enzyme concentration, salt concentration, and time. A maximum of 20 to 22 fragments was generated under conditions of low enzyme concentration or short times of incubation. VSV genome-length intracellular RNA of both + and - polarity was also cleaved by RNase III. In contrast to the findings with virion-length RNA, however, the migration rates of VSV mRNA's purified by chromatography on polyuridylic acid-Sepharose were unaffected by treatment with RNase III. These results show that specific sites in the virion RNA and its full-length complement can be recognized by RNase III. Sites of this type are not present in the polyadenylic acid-containing mRNA, however.
Histone modifications in simian virus 40 and in nucleoprotein complexes containing supercoiled viral DNA
Authors: Chen Y H , MacGregor J P , Goldstein D A , Hall M R
Published: January 2020

Simian virus (SV40) nucleoprotein complexes containing circular supercoiled viral DNA were extracted from infected cells and purified by differential centrifugation. The protein content of these complexes was compared by electrophoresis on 15% acrylamide gels with the protein content of purified SV40 virions and with histones from virus-infected cells. The electrophoretic patterns of histones from each of the sources revealed several major differences. SV40 virions contained histones H3, H2B, H2A, and H4 but not H1. Nucleoprotein complexes and host cells contained all five major histone groups. Relative to cellular histones, virion and nucleoprotein complex histones were enriched 15 to 40% in histones H3 and H4. In addition to the major classes of histones, several subfractions of histones H1, H3, and H4 were observed in acrylamide gels of proteins from SV40 virions and viral nucleoprotein complexes. Acetate labeling experiments indicated that each subfraction of histones H3 and H4 had a different level of acetylation. The histones from SV40 virions and nucleoprotein complexes were acetylated to significantly higher levels than those of infected host cells. No apparent differences in phosphorylation of the major histone groups were observed.
Post-translational modification of Rauscher leukemia virus precursor polyproteins encoded by the gag gene
Authors: Schultz A M , Rabin E H , Oroszlan S
Published: January 2020

Post-translational modifications of retrovirus gag gene-encoded polyproteins include proteolytic cleavage, phosphorylation, and glycosylation. To study the sequence of these events, we labeled JLS-V9 cells chronically infected with Rauscher murine leukemia virus in pulse-chase experiments with the radioactive precursors [35S]methionine, [14C]mannose, [3H]glucosamine, and [32P]phosphate. Newly synthesized gag polyproteins which incorporated label, and the modified products derived from them, were identified by immunoprecipitation of cell lysates with anti-p30 rabbit serum, followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Pulse-chase experiments were carried out in the presence as well as in the absence of tunicamycin, an inhibitor of glycosylation. Among the three major polyproteins synthesized in the absence of tunicamycin, two were found to be glycosylated but not phosphorylated. These were designated gPr80gag and gP94gag. Both shared identical [35S]methionine peptides with Pr65gag and p30. Of the two nonglycosylated precursors, Pr65gag and Pr75gag, only Pr65gag was found to be detectably phosphorylated, and Pr75gag could be readily identified only when glycosylation was inhibited. On the basis of these results, a scheme for the post-translational modification of gag polyproteins is proposed. According to this scheme the gag gene-encoded polyproteins are processed from a common precursor, Pr75gag, by two divergent pathways: one leading through the intermediate Pr65gag to internal virion components via cleavage and phosphorylation and the other via tunicamycin-sensitive mannosylation to the intermediate gPr80gag, which is further glycosylated to yield cell surface polyprotein gP94gag.
Simian virus 40 early mRNA's. I. Genomic localization of 3' and 5' termini and two major splices in mRNA from transformed and lytically infected cells
Authors: Reddy V B , Ghosh P K , Lebowitz P , Piatak M , Weissman S M
Published: January 2020

We have studied the structure of polyadenylated virus-specific cytoplasmic mRNA's in mouse and human cells transformed by simian virus 40 and in monkey cells infected with simian virus 40 in the presence of cytosine arabinoside by means of reverse transcriptase-catalyzed complementary DNA synthesis and complementary DNA sequencing. Abundant mRNA species containing splices from residues 4490 to 4557 (0.533 to 0.546 map units [m.u.]) and 4490 to 4837 (0.533 to 0.600 m.u.) were identified in both transformed and infected cells. Two principal reverse transcriptase stops were observed at the 5' termini of these mRNA's, both occurring with approximately equal frequency. The most distal of these stops was localized at residues 5152 to 5154 (0.660 m.u.), and the second was at residues 5147 to 5148 (0.659 m.u.). Several additional minor stops, between approximately 0.62 and 0.65 m.u., were also found on complementary DNA copied from transformed cell mRNA; in contrast, only one additional stop was present on complementary DNA copied from early lytic mRNA. These data suggest the presence of a prinicipal 5' terminus of early lytic and transformed cell mRNA's at residues 5152 to 5154 and raise the possibility of additional 5' termini at one or more locations in the 0.62 to 0.659 m.u. region of these mRNA's. Transformed cell mRNA was also found to contain a single 3' terminus at positions 2504 and 2505 (0.153 m.u.); termini lying beyond this site were not detected.
Initiation of DNA Synthesis by the Avian Retrovirus Reverse Transcriptase In Vitro: Nature and Location of the Oligodeoxycytidylic Acid Primer Binding Site
Authors: Collett Marc S. , Perdue Michael L. , Faras Anthony J.
Published: January 2020

We have investigated the use of oligodeoxycytidylic acid [oligo(dC)] as a primer for the initiation of DNA synthesis by the avian retrovirus reverse transcriptase in vitro, employing the viral RNA genome as template. The addition of oligo(dC)
12-18
to viral 35S RNA results in a stimulation of DNA synthesis by the viral RNA-directed DNA polymerase comparable to that observed when oligo(dT) is employed as a primer. Under similar conditions neither oligo(dA)
12-18
nor oligo(dG)
12-18
was active as primer for transcription of the avian retrovirus genome. Several different approaches have been employed to localize the oligo(dC)
12-18
binding site on the viral genome, including isolation of poly(A)-containing fragments, competition hybridization, and RNase H hydrolysis. These analyses indicate that oligo(dC)
12-18
binds to a site approximately 2,000 to 3,000 nucleotides from the 3′ terminus of the genome of transforming strains of avian sarcoma viruses and approximately 700 to 1,000 nucleotides from the 3′ terminus of nontransforming avian retroviruses. Therefore, the major site of initiation of DNA synthesis by oligo(dC)
12-18
appears to be in the vicinity of the 3′ end of the
env
gene and the 5′ end of the
src
gene, although the presence of minor initiation sites located elsewhere on the viral genome cannot be excluded by these data. Characterization of oligonucleotides after pancreatic RNase hydrolysis and poly(C)-Sepharose chromatography of viral RNA directly demonstrates the presence of oligoguanylic acid residues in the avian sarcoma virus genome. DNA sequences transcribed from the oligo(dC) primer appear to be conserved in all of the avian leukosis-sarcoma viruses tested. The use of oligo(dC) as a tool for the production of specific complementary DNA probes is discussed.
Biochemical studies on the Phlebotomus fever group viruses (Bunyaviridae family)
Authors: Robeson G , el Said L H , Brandt W , Dalrymple J , Bishop D H
Published: January 2020

Analyses of the virion polypeptides and genomes of several Phlebotomus fever group viruses, Karimabad, Punta Toro, Chagres, and the sandfly fever Sicilian serotype viruses, have established that they are biochemically similar to the accepted members of the Bunyaviridae family. Like snowshoe hare virus (a member of the California serogroup of the Bunyavirus genus of the Bunyaviridae family), Karimabad, Punta Toro, Chagres, and the sandfly fever Sicilian serotype viruses all have three viral RNA species, designated large (L), medium (M), and small (S). Oligonucleotide fingerprint analyses of Karimabad and Punta Toro virus RNA species indicated that their L, M, and S RNA species are unique. By polyacrylamide gel electrophoresis it was determined for Karimabad virus that the apparent molecular weights of its L, M, and S RNA species are 2.6 X 10(6), 2.2 X 10(6), and 0.8 X 10(6), respectively. For Punta Toro virus, the apparent molecular weights of its L, M, and S RNA species are 2.8 X 10(6), 1.8 X 10(6), and 0.75 X 10(6), respectively. The major internal nucleocapsid (N) protein of Karimabad virus was found to have a molecular weight of 21 X 10(3). A similar polypeptide size class was identified in preparations of sandfly fever Sicilian serotype, Chagres, and Punta Toro viruses. The Karimabad virus glycoproteins formed the external surface projections on virus particles and could be removed from virus preparations by protease treatment. The glycoproteins in an unreduced sample could be resolved into two size classes by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. They had apparent molecular weights of 62 X 10(3) and 50 X 10(3) in continuous polyacrylamide gels. When Karimabad virus preparations were reduced with 1% beta-mercaptoethanol, prior to resolution by continuous polyacrylamide gel electrophoresis, all the viral glycoprotein was recovered in a single size class, having an apparent molecular weight of 62 X 10(3). Two or three major virion polypeptides have been identified in preparations of Punta Toro, Chagres, and sandfly fever Sicilian serotype viruses.
Expression of baboon endogenous virus in exogenously infected baboon cells
Authors: Lavelle G , Foote L , Heberling R L , Kalter S S
Published: January 2020

Strains of low-passage, fetal diploid, baboon (Papio cynocephalus) fibroblasts were susceptible to exogenous infection with three independent isolates of baboon endogenous virus, as measured by an immunofluorescence assay specific for viral p28. Infectivity of the M7 strain of baboon endogenous virus for baboon cells of fetal skin muscle origin was equivalent to that for human and dog cells in that similar, linear, single-hit titration patterns were obtained. The assay for supernatant RNA-dependent DNA polymerase, however, showed that baboon cells produced only low levels of virus after infection compared with the production by heterologous cells. The results showed that baboon endogenous virus was capable of penetrating baboon cells and that viral genes were expressed in infected cells. Replication of complete infectious virus was restricted, however, indicating that in this primate system homologous cells differentially regulated the expression of viral genes.
Role of virus variants and cells in maintenance of persistent infection by measles virus
Authors: Fisher L E , Rapp F
Published: January 2020

Hamster embryo fibroblasts persistently infected with a derivative of the Schwarz vaccine strain of measles virus spontaneously released virus particles with an average buoyant density considerably lower than that of the parental virus. The released virus contained all of the measles virus structural proteins and interfered with replication of standard virus. All of the virus structural proteins were associated with a membrane-free cytoplasmic extract from the persistently infected cells. Membrane-free cytoplasmic extracts prepared from Vero cells lytically infected with Schwarz strain measles contained little or no virus envelope structural protein. Maintenance of persistent infection may involve both the presence of virus variants and a defect in the ability of the infected cell to replicate the virus efficiently.
Polyoma viruses with mutations at endonuclease HindII site 1: alterations at the COOH terminus of VP1
Authors: Bendig M M , Folk W R , Gibson W
Published: January 2020

Four mutants of polyoma virus lacking endonuclease HindII site 1 were isolated and characterized with respect to the VP1 coding sequence. Three of these mutants had deletions that removed 0.2 to 0.3% of the genome. All three deletion mutants encoded VP1 proteins that were smaller than wild type and that lacked one or more tryptic peptides normally found in the wild-type VP1 protein. Our results suggest the HindII site 1 is at, or very near, the carboxy terminal end of the coding sequence for VP1. A model for the peptide organization in that region is presented.
Structural analysis of the intracellular RNAs of murine mammary tumor virus
Authors: Robertson D L , Varmus H E
Published: January 2020

We have characterized murine mammary tumor virus (MuMTV)-specific RNA in several types of cells in which viral DNA is transcribed into RNA: cultured GR mouse mammary tumor cells, S49 lymphoma cells from BALB/c mice, lactating mammary glands from C57BL/6 mice, and mink lung cells infected in vitro with MuMTV. In all cell types studied, there are three distinct species of intracellular viral RNA, with sedimentation coefficients of 35S, 24S, and 13S (or molecular weights of 3.1 X 10(6), 1.5 X 10(6), and 0.37 X 10(6), as determined by rate-zonal sedimentation in sucrose gradients and by electrophoresis in agarose gels under denaturing conditions. These three viral RNA species appear to be present regardless of viral RNA concentration, responsiveness to glucocorticoid hormones, production of extracellular virus, and use of either endogenous or acquired MuMTV proviral DNA as template. The three viral RNAs display characteristics of mRNAs in that they are polyadenylated, associated with polyribosomes, and released from polyribosomes by treatment with EDTA; hence all three species presumably direct the synthesis of virus-coded proteins. The two larger species of viral RNA are probably responsible for synthesis of the structural proteins of the virion, but the function of the 13S RNA is not known. Both of the subgenomic RNAs contain sequences found at the 3' terminus of 35S (or genomic) RNA. However, only the 24S RNA (not the 13S RNA) contains sequences which are located at the 5' terminus of 35S RNA and are apparently transposed during RNA synthesis of maturation, as described for subgenomic mRNA's of other retroviruses.
Nucleotide sequence deletions within the coding region for small-t antigen of simian virus 40
Authors: Volckaert G , Feunteun J , Crawford L V , Berg P , Fiers W
Published: January 2020

Simian virus 40 early mutants with deletions mapping in the 0.53-0.60 region have been sequenced by the Maxam and Gilbert approach. All these deletions effect the small-t gene. The size of the shortened small-t-related polypeptides produced by several of the mutants has been compared with the molecular weight as deduced from the nucleotide sequence. There was good agreement for the mutants dl890, dl891, and dl2102. For dl2121 and dl2122 the small-t-related protein was considerably larger than expected. It is possible to explain this result on the basis of the nucleotide sequence: the normal splicing event of the small-t mRNA still occurs, but as the deletion shifts the reading frame, translation of the small-t-related polypeptide continues beyond the small-t splice, but in a different reading frame than large-T. Mutants dl883, dl884, and dl2112 have lost one of the small-t splicing boundaries, and no (or minute amonts of) small-t-related protein has been observed in mutant-infected cells. The possible relationship between splicing and transport of polyadenylic acid-containing mRNA from the nucleus to the cytoplasm in vertebrae cells is discussed.
5′-Terminal Sequences of Spring Viremia of Carp Virus RNA Synthesized In Vitro
Authors: Gupta Kailash C. , Bishop David H. L. , Roy Polly
Published: January 2020

Sequence analyses have been undertaken on the 5′ termini of the RNA species synthesized in vitro at 22°C by Spring viremia of carp virion (SVCV)-associated transcriptase by using virus grown in mammalian BHK-21 cells. SVCV product RNA was synthesized in the absence or presence of low (0.56 μM) or high (0.8 mM) concentrations of added
S
-adenosyl-
l
-methionine (SAM). Two major sequences obtained in the absence (or in low concentrations) of SAM have been shown to be GpppAp and GpppAmpAp(C). A minor sequence detected when a low concentration of [
3
H]SAM was added to reaction mixtures was 7mGpppAmpAp. Larger quantities of the 7mGpppAmpAp(C) sequence, in addition to the GpppAmpAp(C) sequence, were obtained when high concentrations of SAM were used, and under these conditions no GpppAp sequences were detected. It has further been shown that with low concentrations of [
3
H]SAM the principle in vitro methylation of adenosine in SVCV product RNA occurred at the 2′-
O
-ribose position; no methylation at the
N
6
-adenosine position and no internal product RNA methylation were detected. Comparison of the SVCV results to the published data on the 5′-terminal structures of the in vitro or in vivo mRNA species of vesicular stomatitis virus Indiana and vesicular stomatitis virus New Jersey suggests that the 5′ sequences of transcript RNA of different rhabdoviruses may have been conserved.
Restriction Maps of Five
Autographa californica M
NPV Variants,
Trichoplusia ni M
NPV, and
Galleria mellonella M
NPV DNAs with Endonucleases
Sma
I,
Kpn
I,
Bam
HI,
Sac
I,
Xho
I, and
Eco
RI
Authors: Smith Gale E. , Summers Max D.
Published: January 2020

The restriction sites of
Autographa californica
nuclear polyhedrosis virus (Ac
M
NPV) E2 DNA were mapped for the endonucleases
Sma
I,
Kpn
I,
Bam
HI,
Sac
I,
Xho
I, and
Eco
RI. The restriction maps of four other Ac
M
NPV variants,
Trichoplusia ni
(Tn
M
NPV), and
Galleria mellonella
(Gm
M
NPV) genomes were determined and compared to the endonuclease cleavage maps of Ac
M
NPV E2 DNA. The viral structural polypeptides of Ac
M
NPV variants S3, E2, S1, M3, and R9 were the same when analyzed by polyacrylamide gel electrophoresis. The major structural polypeptides of Gm
M
NPV and Tn
M
NPV had the same pattern in polyacrylamide gels as did Ac
M
NPV structural polypeptides. Gm
M
NPV and Tn
M
NPV had several minor structural protein differences as compared with Ac
M
NPV. Ac
M
NPV variants, Tn
M
NPV, and Gm
M
NPV were distinct but with very similar genomes and protein structures.
In vivo assembly of a biological membrane of defined size, shape, and lipid composition
Authors: Brewer G J
Published: January 2020

At restrictive temperature, mutant ts1 of bacteriophage PM2 makes membrane vesicles inside infected Alteromonas espejiana. A shift from restrictive to permissive temperature resulted in rapid maturation to infectious virions. The membrane vesicles were isolated from cellular membranes by sucrose density gradient centrifugation. Analysis of the unique peak at rho = 1.190 g/cm3 showed spheres of two diameters, 50 nm and 54 nm. The wild-type virus is icosahedral with an average diameter of 60 nm. Gel electrophoresis indicated the absence in the vesicles of the coat and spike proteins. sp27 and sp43, respectively, and the presence of only one viral structural protein, sp6.6. DNA was also present. The lipid in the vesicles was composed of phosphatidylglycerol and phosphatidylethanolamine in a proportion similar to that of the wild-type virus, whose ratio is nearly the inverse of that found in the host membrane. Thus, membrane vesicles made by mutant ts1 resembled the membrane of the wild-type virus in size, shape, and lipid composition, but contained only one of the four structural proteins of the virus. This hydrophobic protein, sp6.6 may be responsible for stimulating membrane morphogenesis.
Multiple copies of Shope virus DNA are present in cells of benign and malignant non-virus-producing neoplasms
Authors: Stevens J G , Wettstein F O
Published: January 2020

In an initial efforts to characterize the virological basis of neoplasia in the Shope papilloma-carcinoma system, the extent to which the viral genome is present in non-virus-producing benign and malignant tumors in domestic rabbits was established. Employing nick-translated radioactive viral DNA purified from productively infected papillomas on cotton tail rabbits as a probe, it was found that (i) papillomas, primary carcinomas, and metastatic carcinomas contain 10 to about 100 copies of the viral genome per diploid cell equivalent of DNA and (ii) viral DNA is present in detectable amounts in essentially all neoplastic cells. These results are consistent with the suggestion that continued presence of the viral genome is necessary for induction and maintenance of malignant as well as benign neoplasms.
Transcription of the bovine parvovirus genome in isolated nuclei
Authors: Patton J T , Stout E R , Bates R C
Published: January 2020

Transcription of the genome of the nondefective parvovirus BPV was examined in nuclei isolated from synchronized bovine fetal spleen cells. The relative levels of total RNA polymerase and RNA polymerase I, II, and III activities in nuclei isolated from BPV-infected and mock-infected cells were found to be similar throughout the course of infection. Hybridization of RNA synthesized in isolated nuceli indicated that BPV-specific RNA synthesis began during the period of 8 to 12 h postinfection and proceeded linearly until at least 20 h postinfection. By 20 h postinfection, 5% of the total RNA synthesized in nuclei from infected cells was virus specific. BPV-specific RNA synthesis was inhibited by 95% in the presence of 0.1 microgram of alpha-amanitin per ml, suggesting that the viral genome is transcribed by cellular RNA polymerase II.
Characterization of pyrimidine deoxyribonucleoside kinase (thymidine kinase) and thymidylate kinase as a multifunctional enzyme in cells transformed by herpes simplex virus type 1 and in cells infected with mutant strains of herpes simplex virus
Authors: Chen M S , Summers W P , Walker J , Summers W C , Prusoff W H
Published: January 2020

Pyrimidine deoxyribonucleoside kinase (thymidine kinase [TK]) was purified from two herpes simplex virus type 1 (HVS-1)-transformed TK-deficient mouse (LMTK-) cell lines and from LMTK- cells infected with HSV-1 mutant viruses coding for variant TK enzymes. These preparations exhibited normal or variant virus-induced thymidylate kinase activities correlating with their relative TK activities. Neither virus-induced activity was detected in LMTK- cells infected with an HSV-1 TK-deficient mutant. These results suggest that HSV-1 thymidylate kinase activity and TK activity are mediated by the same protein.
RNA synthesis of vesicular stomatitis virus-infected cells: in vivo regulation of replication
Authors: Simonsen C C , Batt-Humphries S , Summers D F
Published: January 2020

Pulse-labeling of vesicular stomatitis virus-infected HeLa and BHK cells with [3H]uridine throughout the infectious cycle demonstrated two peaks of uridine incorporation into virus-specific RNA molecules. By separating total RNA synthesis into replication and transcription products, we showed that replication occurs over a shorter period of time in one peak synthesis. The biphasic nature of uridine incorporation is in part due to a general membrane phenomenon of reduced metabolite transport during vesicular stomatis virus infection and in part due to the apparent uncoupling of replication and transcription. A change in the ratio of newly synthesized plus and minus strands of the genome length (42S) RNA was found as the infection proceeded. Early in the infection, plus-stranded 42S RNA comprised 40% of the total genome length RNA synthesis, whereas late in infection, only 15 to 20% of the 42S RNA synthesized was complementary to the virion minus strand. Our data suggest that the rate of synthesis of plus-stranded 42S RNA was constant throughout the infection. The rate of virus release was determined by monitoring the uptake of [3H]uridine into released virus particles. Virus maturation and release are closely associated with the assembly of 42S RNA-containing nucleocapsids.
Restriction cleavage map of SP01 DNA: general location of early, middle, and late genes
Authors: Pero J , Hannett N M , Talkington C
Published: January 2020

A detailed restriction endonuclease map for the genome of Bacillus subtilis phage SP01 is presented. Sites of cleavage for the restriction enzymes BglII, EcoRI, HaeIII, and SalI were determined. This physical map showed that SP01 DNA was 140 kilobases in length and contained a repeated sequence of 12.4 kilobases at its termini. Combined with previously published information, we were also able to identify the general locations of genes expressed at early, middle, or late times in the phage lytic cycle. In particular, early genes were largely clustered in the terminal repeats, whereas a major cluster of late genes was located in the left-central portion of the genome.
Characterization of visna virus mRNA
Authors: Filippi P , Brahic M , Vigne R , Tamalet J
Published: January 2020

Visna virus is a retrovirus responsible for a classical slow infection of the central nervous system of sheep. In the present work we focused our attention on the viral mRNA's. We found that, during the acute infection in vitro, (i) viral mRNA's amount to only 0.1% of the total cytoplasmic RNA, (ii) 20% of the total cytoplasmic viral RNA is found in polyribosomes, and (iii) three viral mRNA's can be identified by sucrose gradient sedimentation or polyacrylamide gel electrophoresis. Their sedimentation coefficients are 36S, 27S, and 21S.
Functional relationship between bacteriophages G4 and phi X174
Authors: Borrias W E , Hagenaar M , Van Den Brekel R , Kühlemeijer C , Weisbeek P J
Published: January 2020

Mutants of bacteriophage G4 were isolated and characterized, and their mutations were mapped. They constitute six different genes, namely, A, B, E, F, G, and H. The functional relationship with bacteriophage phi X174 was determined by complementation experiments using amber mutants of phi X and amber mutants of G4. Bacteriophage phi X was able to use the products of G4 genes E, F, G, and H. In bacteriophage G4, however, only the phi X gene H product was functional.
Tubular subviral structure produced in adenovirus-infected KB cells
Authors: Dunker R , Brown D T
Published: January 2020

At 40 to 90 h after infection with high multiplicities of adenovirus type 2, 4 to 15% of KB cells produced relatively few intranuclear virions detectable by electron microscopy. The nuclei of these cells were found to contain long tubular structures which were made up at least in part by adenovirus structural proteins. The ends of these tubular structures were frequently terminated by morphologically normal adenovirions in varying degrees of completeness. Circumstantial evidence suggests that the production of these aberrant virus structures results from the malfunction or absence of some essential host-provided function and not from a defect in the infecting virus.
Molecular evidence for a type C retrovirus etiology of the lymphoproliferative disease of turkeys
Authors: Gazit A , Yaniv A , Ianconescu M , Perk K , Aizenberg B , Zimber A
Published: January 2020

Recently, we isolated from the blood of lymphoproliferative disease (LPD)-affected turkeys a type C retrovirus distinct from the avian leukosis-sarcoma virus complex and the reticuloendotheliosis virus group. We present molecular evidence for the implication of this virus in the LPD of turkeys. Using complementary DNA of LPD viral RNA, we found that the LPD viral genome is specifically and efficiently transcribed (2,500 copies per cell) in LPD tumor cells. Moreover, the LPD tumor cells contained newly inserted LPD viral information (5 to 10 copies per haploid genome), which was not present before the infection. From the absence of LPD virus-specific sequences in the normal cell genome of turkeys, it was concluded that the LPD virus is not an endogenous virus of turkeys. DNA-DNA annealing experiments revealed that the degree of sequence homology between LPD viral complementary DNA and cellular DNA of turkeys was not higher than that between LPD viral complementary DNA and cellular DNA of other species, thus indicating that the virus does not originate from turkeys.
Gene expression of herpes simplex virus. I. Analysis of cytoplasmic RNAs in infected xeroderma pigmentosum cells
Authors: Talley-Brown S , Millette R L
Published: January 2020

RNAs which are synthesized and accumulate in the cytoplasm of uninfected and herpes simplex virus type 1 (HSV-1)-infected xeroderma pigmentosum (XP) cells in the presence of cycloheximide (early RNAs) or absence of drugs (late RNAs) were analyzed by electrophoresis through denaturing polyacrylamide gradient slab gels. HSV RNAs were selected by hybridization ot HSV DNA covalently bound to cellulose. No HSV-specific low-molecular-weight (4S to 10S) RNAs were detected. However, several changes were observed in the electrophoretic pattern of the host low-molecular-weight RNAs during HSV infection. Five HSV RNAs ranging in size from 16S to 28S accumulated in the cytoplasm of infected XP cells in the presence of cycloheximide. These are of the size range predicted to encode the major early viral polypeptides. The cytoplasmic and polyadenylated early RNAs from HSV-infected XP cells were translated in vitro to produce proteins whose electrophoretic pattern resembled that of the early viral proteins synthesized in vivo.
Species specificity of interferon action: maintenance and establishment of the antiviral state in the presence of a heterospecific nucleus
Authors: Veomett M J , Veomett G E
Published: January 2020

The expression of the interferon-induced antiviral state was studied in heterokaryons and cytoplasmic hybrids (cybrids). An autoradiographic assay for the antiviral state, in which the percentage of cells containing vaccinia viral DNA factories was determined, was used. The expression of the antiviral state was dominant in homokaryons and heterokaryons formed by fusion of interferon-treated cells with untreated cells. Cytoplasts derived from treated cells conferred resistance to virus growth on cybrids formed by fusing such cytoplasts with untreated cells. Treatment of L cell x HeLa cell heterokaryons with human interferon or mouse interferon was much less effective in inducing a detectable antiviral state than was similar treatment of parental cells with homospecific interferon. The antiviral state was fully induced when heterokaryons were treated simultaneously with both types of interferon. Cybrids formed by fusing L cell cytoplasts with HeLa cells or HeLa cytoplasts with L cells did not enter a detectable antiviral state after treatment with interferon specific for the cell type of the enucleated parent. However, treatment of cybrids with interferon specific for the cell type of the nucleated parent was effective in inducing a detectable antiviral state.
Establishment of a lymphoblastoid cell line and isolation of an Epstein-Barr-related virus of gorilla origin
Authors: Neubauer R H , Rabin H , Strnad B C , Nonoyama M , Nelson-Rees W A
Published: January 2020

A B-lymphoid cell line was established from a normal gorilla. The cells contained Epstein-Barr virus-related antigens, and herpesvirus particles were demonstrated by electron microscopy. DNA-DNA reassociation kinétics revealed 30 to 40% hybridization to Epstein-Barr virus with 50 genomes per cell. Examination of the viral nuclear antigen with gorilla sera showed this to be a unique isolate termed Herpesvirus gorilla. H. gorilla transformed gibbon B-lymphocytes in vitro.
Cellular proteins associated with simian virus 40 early gene products in newly infected cells
Authors: Yang Y C , Hearing P , Rundell K
Published: January 2020

Immunoprecipitates of extracts of simian virus 40-infected permissive monkey kidney cells contained two proteins with molecular weights of 56,000 and 32,000 (52K and 32K) in addition to the known viral early gene products. Immunoprecipitates of cells infected with the 0.54-0.59 deletion mutants that lack the viral 17K gene product did not contain thhe 56K and 32K proteins. The additional proteins appeared in immunoprecipitates of deletion mutant extracts if unlabeled extracts of wild-type-infected cells were added before addition of antiserum. The proteins can also be identified in uninfected cells by co-precipitation with unlabeled viral proteins. Thus, it appears that the 56K and 32K proteins are cellular products that associate with the viral proteins, the 17K in particular, and are indirectly immunoprecipitated by anti-tumor serum.
Conserved polynucleotide sequences among the genomes of papillomaviruses
Authors: Law M F , Lancaster W D , Howley P M
Published: January 2020

The DNAs of different members of the Papillomavirus genus of papovaviruses were analyzed for nucleotide sequence homology. Under standard hybridization conditions (Tm - 28 degrees C), no homology was detectable among the genomes of human papillomavirus type 1 (HPV-1), bovine papillomavirus type 2 (BPV-2), or cottontail rabbit (Shope) papillomavirus (CRPV). However, under less stringent conditions (i.e., Tm - 43 degrees C), stable hybrids were formed between radiolabeled DNAs of CRPV, BPV-1, or BPV-2 and the HindIII-HpaI A, B, and C fragments of HPV-1. Under these same conditions, radiolabeled CRPV and HPV-1 DNAs formed stable hybrids with HincII B and C fragments of BPV-2 DNA. These results indicate that there are regions of homology with as much as 70% base match among all these papillomavirus genomes. Furthermore, unlabeled HPV-1 DNA competitively inhibited the specific hybridization of radiolabeled CRPV DNA to bpv-2 DNA fragments, indicating that the homologous DNA segments are common among these remotely related papillomavirus genomes. These conserved sequences are specific for the Papillomavirus genus of papovaviruses as evidenced by the lack of hybridization between HPV-1 DNA and either simian virus 40 or human papovavirus BK DNA under identical conditions. These results indicate a close evolutionary relationship among the papillomaviruses and further establish the papillomaviruses and polyoma viruses as distinct genera.
Infective substructures of measles virus from acutely and persistently infected cells
Authors: Rozenblatt S , Koch T , Pinhasi O , Bratosin S
Published: January 2020

Ribonucleoprotein from cells acutely or persistently infected with measles virus were shown to be infectious by the calcium phosphate technique. Very little or no infectivity was obtained when calcium phosphate precipitation was omitted. Electron microscopy showed that the majority of ribonucleoprotein structures isolated from acutely infected cells were folded, whereas those from persistently infected cells were linear in appearance.
Pheasant virus DNA polymerase is related to avian leukosis virus DNA polymerase at the active site
Authors: Bauer G , Temin H M
Published: January 2020

The DNA polymerase from Amherst pheasant virus (APV), a member of the pheasant virus species of retroviruses, was compared to the DNA polymerases of avian leukosis viruses (ALV) and a reticuloendotheliosis virus (spleen necrosis virus (SNV)). Immunoglobulin inhibition tests and competition immunoassays showed that APV and ALV DNA polymerases are closely related at their active sites. The determinants common to their active sites are not shared by SNV DNA polymerase. Bu using a species-specific radioimmunoassay, it was shown that both APV and SNV DNA polymerases are grossly different from ALV DNA polymerase. The specificity of the relationship of the active sites of APV and ALV DNA polymerases was confirmed by a heterologous radioimmunoassay. Our data indicate that pheasant viruses are evolutionarily linked to ALV.
Is the injection of DNA enough to cause bacteriophage P22-induced changes in the cellular transport process of Salmonella typhimurium?
Authors: Bandyopadhyay P N , Das Gupta B , Joshi A , Chakravorty M
Published: January 2020

It was demonstrated earlier in this laboratory that phage P22 induces a transient depression in the cellular transport processes of the host Salmonella typhimurium immediately after infection and that an effective injection process is enough to cause the depression. By using defective phage particles that contain host DNA instead of phage DNA for infection, it has been demonstrated that the injection of phage-specific DNA is essential for this. The defective particles adsorbed to the host and injected their DNA, but the cellular transport processes of the host were not altered. Thus, the injection of host DNA by the phage fails to affect the transport process. Insensitivity of the phage DNA-induced depression in transport to chloramphenicol rules out the involvement of newly synthesized protein in this change and indirectly suggests the possible role of phage DNA-associated internal proteins of P22.
Replication of polyoma DNA in isolated nuclei: analysis of replication fork movement
Authors: Magnusson G , Nilsson M G
Published: January 2020

The movement of replication forks during polyoma DNA synthesis in isolated nuclei was analyzed by digesting newly synthesized DNA with the restriction endonuclease HpaII which cleaves polyoma DNA into eight unique fragments. The terminus of in vitro DNA synthesis was identified by cleaving newly completed molecules with HpaII. The distribution of label in the restriction fragments showed that the in vitro DNA synthesis was bidirectional and had the normal terminus of replication. Analysis of replicative intermediates pulse-labeled in vitro further suggested that DNA synthesis in isolated nuclei is an ordered process similar to replication in intact cells. Replication forks moved with a constant rate from the origin towards the terminus of replication. The nonlinear course of the DNA synthesis reaction in the isolated nuclei seems to result from the random inactivation of replication forks rather than a decrease in the rate of fork movement. During the in vitro synthesis a replication fork could maximally synthesize a DNA chain about 1,000 nucleotides long. The results suggest that some replication forks might be initiated in vitro at the origin of replication.
Intracellular localization of viral polypeptides during simian virus 40 infection
Authors: Kasamatsu H , Nehorayan A
Published: January 2020

African green monkey kidney cells infected by simian virus 40 were analyzed by immunofluorescence techniques for the nature and the time course of the appearance of viral polypeptides during infection. Reagents used in the study were anti-Vpl sera and affinity-purified anti-Vpl immunoglobulin G, anti-Vp3 sera, antivirus (anti-V) sera, and anti-tumor antigen sera. The results are summarized as follows. (i) Three types of staining, nuclear, perinuclear, and perinuclear accompanied by cytoplasmic staining, were observed in infected cells in reaction with anti-vpl antibody. In addition, a highly structured staining was observed at the periphery of nuclei of infected cells late in infection. (ii) In reaction with anti-Vp3 serum, the staining was confined within nuclei of cells throughout infection. (iii) Vp1 and Vp3 antigens seem to occupy different spacial regions of the nuclear area in cells. (iv) Vp1 and Vp3 antigens were expressed simultaneously during infection. (v) Centriolar staining observed early in infection paralleled the appearance of tumor (T-) antigen until 24 h after infection, after which time the frequency of positive centriolar staining decreased as infection progressed. (vi) T-antigen was first expressed at about 8 h after infection, and Vp1 and Vp3 antigens were first expressed at about 20 h after infection.
Density dependent inhibition of both growth and T-antigen expression in revertants isolated from simian virus 40-transformed mouse SVT2 cells
Authors: Gurney E G , Gurney T
Published: January 2020

Phenotypic revertants were isolated from simian virus 40-transformed cells in order to examine the relationship between simian virus 40 T-antigen expression and G1 arrest of growth. Revertant clones with increased adherence were selected from cultures of SVT2, a simian virus 40-transformed BALB/c mouse cell line, and screened to find arrestable revertant clones which inhibited DNA synthesis when crowded. The clones selected from untreated SVT2 were unstable and showed little or no inhibition of DNA synthesis when crowded. Stable revertants were found after treatment of SVT2 with Colcemid to increase ploidy. The stable revertants all lost most transformed growth properties tested, including tumorigenicity, but only a few showed the same degree of inhibition of DNA synthesis at high cell density as BALB/3T3. All revertant clones expressed T antigen at low cell density. Three revertants showed coordinate inhibition of DNA synthesis and apparent loss of T antigen at high cell density. We suggest that changes in gene dosage rather than mutations caused the altered properties of the new revertants and that continued DNA synthesis in confluent cultures may be the transformed phenotype that requires the least simian virus 40 T antigen.
Production of monoclonal antibodies against nucleocapsid proteins of herpes simplex virus types 1 and 2
Authors: Zweig M , Heilman C J , Rabin H , Hopkins R F , Neubauer R H , Hampar B
Published: January 2020

We prepared mouse hybrid cell lines which produced antibodies against herpes simplex virus type 1 and 2 nucleocapsids. Cell lines 1D4 and 3E1, respectively, secreted immunoglobulin G1 herpes simplex virus type 1 and immunoglobulin G1 herpes simplex virus type 2 antibodies which immunoprecipitated proteins designated p40 and p45 from homologous nucleocapsid preparations but precipitated no proteins from heterologous preparations. In contrast, guinea pig antisera prepared against either herpes simplex virus type 1 or 2 p40 precipitated p40 and p45 from both homologous and heterologous preparations. These findings suggest that p40 and p45 possess similar antigenic determinants and that the monoclonal antibodies that were tested reacted preferentially with the homologous determinants.
Isolation of influenza C virus recombinants
Authors: Racaniello V R , Palese P
Published: January 2020

Recombinants between two different influenza C viruses were isolated. In MDCK (canine kidney) cells, one strain, C/JJ/50, caused lytic plaques, whereas C/JHG/66 virus did not produce clear plaques. From a mixed infection of MDCK cells with C/JHG/66 virus and UV-inactivated C/JJ/50 virus, clones were isolated which possessed the clear-plaque phenotype. Fingerprint analyses indicated that the RNAs of parent viruses had different oligonucleotide patterns and that one of the clones derived from the mixed infection was formed by reassortment of parental genes. This recombinant clone most likely inherited RNAs 1, 2, 3, 6, and 7 from C/JGH/66 virus and RNAs 4 and 5 from C/JJ/50 virus.
Transformation of primary rat kidney cells by DNA fragments of weakly oncogenic adenoviruses
Authors: Dijkema R , Dekker B M , van der Feltz M J , van der Eb A J
Published: January 2020

Primary cultures of baby rat kidney (BRK) cells were transformed by intact DNA and DNA fragments of weakly oncogenic human adenovirus types 3 and 7. The smallest fragment found to contain transforming activity was the left-terminal 4% endo R.HindIII fragment (for both adenovirus type 3 and 7 DNAs). The efficiency of transformation of this fragment was low, and no permanent cell line could be established. Left-terminal fragments ranging from 84 to 4,5% of the viral genome could all transform BRK cells with the same efficiency as intact viral DNA. A number of adenovirus type 7 DNA fragment-transformed lines were established and were found to contain persistent viral DNA sequences and adenovirus subgroup B-specific T antigen. Consequently, the transforming functions of adenovirus types 3 and 7 are located at the extreme left-hand end of the genome, and the minimum size for a DNA fragment with transforming activity is 1.0 X 10(6) daltons. These results do not rule out the possibility that viral genes located outside the transforming region may also influence transformation.