bluuebunny/crossref_metadata_2025 huggingface dataset:
Differences in the subpopulations of the structural proteins of polyoma virions and capsids: biological functions of the multiple VP1 species
Authors: Bolen J B , Anders D G , Trempy J , Consigli R A
Published: January 2020

The structural proteins of polyoma virions and capsids were analyzed by isoelectric focusing and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Polyoma virion VP1 was found to be composed of six distinct species which had pI's between pH 6.75 and 5.75. Polyoma capsid VP1 was found to contain four species with pI's between pH 6.60 and 5.75. The different forms of virion and capsid VP1 appeared to be generated by modifications (phosphorylation and acetylation) of the initial translation product. The most basic of the virion VP1 species (pI, pH 6.75) was absent in capsids and was found to be exclusively associated with the viral nucleoprotein complex. Three of the virion VP1 species and three of the capsid VP1 species were found in capsomere preparations enriched for hexon subunits. Two VP1 species were specifically immune precipitated from virions with hemagglutination-inhibiting antibodies. These two VP1 species were common to both virions and capsids. Polyoma virions, but not capsids, possessed a single VP1 species which was immune precipitated with neutralizing antibodies. Both virion and capsid VP2 were found to have pI's of approximately pH 5.50. Virion VP3 had a pI of approximately pH 7.00, whereas capsid VP3 had a pI of approximately pH 6.50.
Reversion by hypotonic medium of the shutoff of protein synthesis induced by encephalomyocarditis virus
Authors: Alonso M A , Carrasco L
Published: January 2020

Infection of human HeLa cells by picornaviruses produces a drastic inhibition of host protein synthesis. Treatment of encephalomyocarditis virus-infected HeLa cells with hypotonic medium reversed this inhibition; no viral protein synthesis was detected. The blockade of viral translation by hypotonic conditions was observed for a wide range of multiplicities of infection. However, only with low virus-to-cell ratios did cellular protein synthesis resume. The ratio of cellular to viral mRNA translation was strongly influenced by the concentration of monovalent ions present in the culture medium: a high concentration of NaCl or KCl favored the translation of viral mRNA and strongly inhibited cellular protein synthesis, whereas the opposite was true when NaCl was omitted from the culture medium. Once viral protein synthesis had been blocked by hypotonic medium treatment, it resumed when the infected cells were placed in a normal or hypertonic medium, indicating that the viral components synthesized in the infected cells were not destroyed by this treatment. These observations reinforced the idea that ions play a role in discriminating between viral and cellular mRNA translation in virus-infected animal cells.
Viral protein expression in producer and nonproducer clones of friend erythroleukemia cell lines
Authors: Anand R , Lilly F , Ruscetti S
Published: January 2020

Erythroleukemia cell lines HFL/d and HFL/b, derived from tumors induced in vivo in BALB/c (H-2d) and congenic BALB.B (H-2b) mice, respectively, by a polycythemia-inducing strain of Friend virus, produced both spleen focus-forming virus (SFFV) and its native NB-tropic helper virus (Friend murine leukemia virus [FMuLV]) during early-passage generations in culture. Eventually each line ceased production of both infectious viruses but retained its tumorigenic potential in syngeneic hosts. Virus-producer and -nonproducer clones of these cell lines were examined for expression of proteins encoded by the SFFV or FMuLV genomes. Lysates of labeled cells were treated with various antiviral sera, and the precipitates were examined by gel electrophoresis. Expression of the FMuLV env gene-encoded precursor protein, gPr84env, was observed in all producer and most nonproducer clones, but the FMuLV gag and pol gene products, Pr65gag and Pr200gag-pol, were uniformly undetectable in nonproducer clones. All HFL/d and HFL/b clones expressed appreciable amounts of the SFFV-encoded envelope protein, gp52, including one exceptional clone which had ceased to express any FMuLV-encoded proteins. The molecular weight of this SFFV-encoded envelope protein was consistently smaller in all HFL/b clones than in HFL/d clones, regardless of their producer or nonproducer status. The virus-nonproducer phenotype thus appears to be due to shutdown of expression of the 5' portion of the FMuLV genome in two independent cell lines.
Involvement of an early human cytomegalovirus function in reactivation of quiescent herpes simplex virus type 2
Authors: Colberg-Poley A M , Isom H C , Rapp F
Published: January 2020

We have previously described an in vitro system in which the function lacking for herpes simplex virus type 2 (HSV-2) replication can be induced by human cytomegalovirus (HCMV). The mechanism of this reactivation of quiescent HSV-2 by HCMV has been further defined. The HCMV function(s) responsible for HSV-2 stimulation was examined temporally, and the fraction of cells in quiescent cultures producing HSV-2 after superinfection was determined. Using independent biological, genetic and molecular techniques we have made the following observations. (i) As early as 12 h after HCMV superinfection, HSV-2 RNA was expressed in latently infected cells. (ii) At 24 h after HCMV superinfection, a time when newly synthesized HCMV was not yet apparent, infectious HSV-2 was produced by reactivated cultures. (iii) Four HCMV temperature-sensitive mutants, which are DNA-negative at nonpermissive temperature and represent four different complementation groups, induced reactivation of HSV-2 at 39.5 degrees C. (iv) Early after HCMV superinfection, 1.6% of quiescent cells could be induced to transcribe HSV-2 information. (v) Early after HCMV superinfection, 0.3% of cells in the quiescent cultures could be induced to yield infectious HSV-2. The finding that a significant interaction can occur between HCMV and quiescent HSV-2 in an in vitro model is noteworthy in light of the knowledge that both of these herpesviruses often reside simultaneously in the human host.
Inverted terminal repetition in adeno-associated virus DNA: independence of the orientation at either end of the genome
Authors: Lusby E , Bohenzky R , Berns K I
Published: January 2020

Complementary strands of adeno-associated virus DNA labeled with 32P at the 5' ends were separated and then self-annealed to form single-stranded circles stabilized by hydrogen bonds between the complementary sequences in the inverted terminal repetitions. We have previously shown that there are two distinct sequences in the terminal repetition which represent an inversion of the first 125 nucleotides (E. Lusby et al., J. Virol. 34:402-409, 1980; I. S. Spear et al., Virology 24:627-634, 1977). Base pairing between terminal sequences of the same orientation leads to a normal double helical structure. If sequences of the opposite orientation pair, an aberrant secondary structure is formed. HpaII digestion of the self-annealed, single-stranded circles led to labeled terminal fragments that corresponded both to those generated from termini of a normal double helical structure and those generated from an aberrant terminal secondary structure. Thus, the orientation of the terminal repetition at one end of the genome is not influenced by the orientation at the other end.
Postinfection control in T4 bacteriophage infection: inhibition of the rep function
Authors: Ebisuzaki K , Jellie S B
Published: January 2020

We suggest that the general mechanism by which T4 phage turns off host macromolecular synthesis involves specific phage proteins which react with key components in the synthetic pathway. Support for this mechanism exists for the inhibition of host RNA synthesis. Here we note that the host rep function was inhibited after T4 phage infection. Since rep functions are known to be involved in host DNA replication, inhibition of rep might alter the course of host DNA replication.
Synthesis of murine mammary tumor viral proteins in vitro
Authors: Sen G C , Racevskis J , Sarkar N H
Published: January 2020

The coding potential of murine mammary tumor viral genomic RNA was investigated by in vitro translation of various size classes of RNAs isolated from the virions. The major products of translation of full-size 35S polyadenylylated virion RNA were gag-related polyproteins of 75,000, 105,000, and 180,000 daltons (P75, P105, and P180, respectively). Studies on the kinetics of translation of these three proteins established that they were synthesized independently and that the smaller proteins were not post-translational cleavage products of the larger proteins. Tryptic peptide mapping showed that almost all of the P75 sequences were contained within P105 and almost all of the P105 sequences were contained within P180. The syntheses of all three proteins were inhibited by m7GTP, indicating that they were translated from capped mRNA's. Although a 24S polyadenylylated RNA had been identified as the intracellular mRNA for env precursor polyprotein, no such protein could be translated from the 24S polyadenylylated RNA isolated from the virions. However, translation of a 14S size class of polyadenylylated virion yielded four prominent proteins of about 36,000, 23,000, 21,000, and 20,000 daltons. These proteins were unrelated to murine mammary tumor viral structural proteins, as suggested from tryptic peptide mapping and immunoprecipitation data. They might be the products of an as-yet-unidentified gene located near the 3' terminus of the murine mammary tumor viral genomic RNA.
Cellular location of Mu DNA replicas
Authors: Pato M L , Waggoner B T
Published: January 2020

To ascertain the form and cellular location of the copies of bacteriophage Mu DNA synthesized during lytic development, DNA from an Escherichia coli lysogen was isolated at intervals after induction of the Mu prophage. Host chromosomes were isolated as intact, folded nucleoids, which could be digested with ribonuclease or heated in the presence of sodium dodecyl sulfate to yield intact, unfolded nucleoid DNA. Almost all of the Mu DNA in induced cells was associated with the nucleoids until shortly before cell lysis, even after unfolding of the nucleoid structure. We suggest that the replicas of Mu DNA are integrated into the host chromosomes, possibly by concerted replication-integration events, and are accumulated there until packaged shortly before cell lysis. Nucleoids also were isolated from induced lambda lysogens and from cells containing plasmid DNA. Most of the plasmid DNA sedimented independently of the unfolded nucleoid DNA, whereas 50% or more of the lambda DNA from induced lysogens cosedimented with unfolded nucleoid DNA. Possible explanations for the association of extrachromosomal DNA with nucleoid DNA are discussed.
Rat sarcoma virus: further analysis of individual viral isolates and the gene product
Authors: Young H A , Rasheed S , Sowder R , Benton C V , Henderson L E
Published: January 2020

Rasheed rat sarcoma virus, derived by in vitro cocultivation of two rat cell lines (Rasheed et al., Proc. Natl. Acad. Sci. U.S.A. 75:2972-2976, 1978), has been reported to code for a protein of 29,000 Mr, immunologically related to the 21,000 Mr src gene product of Harvey and Kirsten sarcoma viruses. Rat sarcoma virus p29 was thought to contain at least part of a rat type C virus structural protein, since antiserum prepared against whole rat virus was able to immunoprecipitate rat sarcoma virus p29 but not Harvey or Kirsten sarcoma virus p21 (Young et al., Proc. Natl. Acad. Sci. U.S.A. 76:3523-3527, 1979). We now report that antiserum directed against rat type C virus p15, but not viral p12, p10, or p27, immunoprecipitated rat sarcoma virus p29. The p15 antiserum was also able to immunoprecipitate both denatured p29 and a peptide derived by V-8 protease cleavage of p29, indicating that this antiserum contains antibodies directed against primary amino acid determinants. Finally, five separate isolates of rat sarcoma virus were found to code for p29, which indicates that a highly specific site of recombination is involved in the generation of sarcoma viruses in rat cells.
Conservation and progressive methylation of Epstein-Barr viral DNA sequences in transformed cells
Authors: Kintner C , Sugden B
Published: January 2020

The structure of intracellular viral DNA from a number of cell lines arising by clonal transformation of human lymphocytes in vitro with Epstein-Barr virus was analyzed. Intracellular viral DNAs were partially purified and digested with several restriction endonucleases, and the products of digestion were separated by electrophoresis in agarose gels. The viral fragments were detected by transferring the DNA from the gel to nitrocellulose sheets, hybridizing radiolabeled recombinant vectors carrying fragments of viral DNA to those transfers, and visualizing the hybrids by autoradiography. These analyses indicated that: (i) regions of repetitious viral DNA do undergo expansion and contraction although one size predominates; (ii) novel sequence arrangements appear in the intracellular viral DNA of different clones but are not found in clones analyzed serially and propagated extensively; (iii) the viral DNA is increasingly methylated upon cell propagation. We have not identified a transformed cell phenotype or a viral phenotype that segregates with the observed progressive methylation. We have not detected in Epstein-Barr viral plasmids analogs of the gross rearrangements of viral DNAs observed after lytic infections with high multiplicities of papova-, adeno-, or herpes simplex viruses.
Two deletions within genes for simian virus 40 structural proteins VP2 and VP3 lead to formation of abnormal transcriptional complexes
Authors: Llopis R , Stark G R
Published: January 2020

The procedure developed by R. M. Fernandez-Muñoz et al. (J. Virol. 29:612-623, 1979) for isolating simian virus 40 (SV 40) chromatin free of disrupted previrions was optimized for preparing late transcriptional complexes, and these complexes were partially characterized. Transcriptional complexes derived from wild-type virus and from several deletion and temperature-sensitive mutants could be activated more than five-fold either by the anionic detergent Sarkosyl or by 300 mM ammonium sulfate, in agreement with the properties of SV40 transcriptional complexes prepared by other procedures. In contrast, complexes from cells infected with deletion mutants dl1261 or dl1262 were not activated at all by a high salt concentration, even though the extent of their activation by Sarkosyl was normal. Mutants dl1261 and dl1262 carry deletions of 54 and 36 base pairs, respectively, at an approximate map position of 0.91, which is within the overlapping genes for the virion proteins VP2 and VP3. The effects of these deletions on transcription in vitro indicate that VP2 or VP3 or both are bound to late transcriptional complexes in a way that affects the progress of initiated RNA polymerase. The properties of late transcriptional complexes derived from wild-type SV40 can be explained by the presence of the following two different kinds of complexes: (i) a minority class (about 20%), which is free of VP2 or VP3, active at low concentrations of ammonium sulfate in vitro, and responsible for late transcription in vivo, and (ii) a majority class (about 80%) with VP2 or VP3 bound, which is inactive at low salt concentrations both in vitro and in vivo but capable of being activated by high salt concentrations or by Sarkosyl. We propose that mutant VP2 and VP3 proteins from dl1261 and dl1262 bind to the majority class of late transcriptional complexes in a way that can be reversed by Sarkosyl but not by a high salt concentration.
Organization of viral genome in a T antigen-negative hamster tumor induced by human papovavirus BK
Authors: Yogo Y , Furuno A , Nozawa A , Uchida S
Published: January 2020

We analyzed by blot hybridization the state and structure of the viral DNA in an exceptional BK virus-induced hamster tumor (choroid plexus papilloma Vn-324) that contains about one copy of the BK virus genome per cell, but no intranuclear T antigen as assayed by indirect immunofluorescence. The BK viral DNA was found to be integrated into cellular DNA at a site in the middle of the early region of the viral genome (between 0.32 and 0.41 map units). The structure of the inserted viral DNA shows that it cannot encode a full-size large T antigen, but may encode small T antigen and an N-terminal portion of large T antigen.
Unusual lectin-binding properties of a herpes simplex virus type 1-specific glycoprotein
Authors: Olofsson S , Jeansson S , Lycke E
Published: January 2020

Lysates from herpes simplex virus type 1-infected cells were subjected to affinity chromatography on soybean and Helix pomatia lectins. One of the virus-specified glycoproteins, probably the herpes simplex virus type 1-specific gC glycoprotein, bound to the lectins and was eluted with N-acetylgalactosamine. The affinity chromatography permitted a high degree of purification of the type-specific glycoprotein with respect to both host cell components and other viral glycoproteins. The lectin affinity pattern of this glycoprotein indicates the presence of a terminal alpha-N-acetylgalactosamine in an oligosaccharide, a finding not reported previously for glycoproteins of enveloped viruses.
Sequence arrangement and biological activity of cloned feline leukemia virus proviruses from a virus-productive human cell line
Authors: Mullins J I , Casey J W , Nicolson M O , Burck K B , Davidson N
Published: January 2020

We examined 14 different feline leukemia virus proviruses from the productively infected human cell line RD(FeLV)-2 after cloning in the modified lambda vector Charon 4A. Each isolate was characterized by restriction digestion and Southern blot analysis. The DNA of each isolate was tested for competence to express virus after uptake by sensitive animal cells (transfection). All but one isolate contained an apparently complete provirus, but only four were infectious. Seven isolates (four noninfectious, three infectious) were studied by heteroduplexing followed by electron microscopy or by S1 nuclease treatment and gel electrophoresis. No regions of nonhomology between proviruses were detected by either criterion, and in no case did we observe homology between flanking sequences. Random shearing or removal of flanking sequences by S1 nuclease had no effect on the status of infectivity of the clones. Thus, we were unable to find molecular differences between infectious and noninfectious proviruses. Our data are consistent with either of the following hypotheses: (i) that there is a short host sequence which is essential as a promoter for virus expression; or (ii) that lack of infectivity is due to small mutations within the proviral genome.
Translational Products of Moloney Murine Sarcoma Virus RNA: Identification of Proteins Encoded by the Murine Sarcoma Virus
src
Gene
Authors: Cremer Kenneth , Reddy E. Premkumar , Aaronson Stuart A.
Published: January 2020

In vitro translation of virion RNA of Moloney murine sarcoma virus (MSV) strain 124 yielded major products having molecular weights of 63,000 (63K), 43K, 40K, 31K, and 24K daltons. A molecularly cloned subgenomic fragment of Moloney MSV comprised of the cellular insertion (
src
) region was utilized in hybridization arrest translation as a means of identifying products of the MSV
src
gene. MSV
src
DNA specifically inhibited synthesis of the 43K, 40K, 31K, and 24K proteins, implying that each of these proteins was coded within the MSV
src
gene. The MSV
src
-specific nature of this family of proteins was further confirmed by partial purification of MSV
src
-containing RNAs from MSV non-producer cells. In vitro translation of enriched cellular RNAs yielded products with molecular weights identical to those of the 43K family of proteins synthesized from virion RNA. Nucleotide sequence analysis of the MSV transforming region has revealed a long open reading frame which includes five methionine codons (Reddy et al., Proc. Natl. Acad. Sci. U.S.A.
77:
5234-5238, 1980). The molecular weights of the four largest proteins that could be synthesized within this open reading frame corresponded closely to the molecular weights of the 43K family of proteins. Partial cyanogen bromide cleavage of each of the three largest proteins resulted in an uncleaved fragment having a molecular weight equal to that of the smallest (24K) protein. These findings provide direct biochemical evidence that the 43K, 40K, 31K, and 24K proteins are related in their carboxy-terminal regions, as well as information concerning the MSV
src
gene coding sequences from which each protein originates:
Four Moloney murine leukemia virus-infected rat cell clones producing replication-defective particles: protein and nucleic acid analyses
Authors: Yoshimura F K , Yamamura J M
Published: January 2020

Four cloned rat cell lines (NX-1 to -4) infected with Moloney murine leukemia virus and defective in virus replication were found to be all different by viral protein and nucleic acid analyses. All four clones produced noninfectious particles and, except for NX-2, at about the same level as wild type. Compared with wild-type virions these defective particles contained larger amounts of gag precursor proteins and very little or no p30 or p15. Analysis of intracellular precursor proteins revealed that NX-2 to -4 synthesized normal Pr65gag, whereas NX-1 produced a slightly smaller precursor. Both NX-1 and NX-4 synthesized an intracellular polyprotein with a size similar to that of wild-type Pr180 gag-pol. Restriction endonuclease analysis of NX-1 to -4 cellular DNA showed that each clone contained a single integrated provirus which possessed large terminal repeat sequences at both the 5' and 3' ends. The proviruses of NX-1 to -3 appeared normal by restriction endonuclease analysis, but NX-4 provirus had a deletion of 1,700 base pairs comprising part of the polymerase region. The noninfectious particles produced by all four clones packaged Moloney viral RNAs and rat RNAs of two different sizes.
Spodoptera frugiperda
Nuclear Polyhedrosis Virus Genome: Physical Maps for Restriction Endonucleases
Bam
HI and
Hin
dIII
Authors: Loh Lambert C. , Hamm John J. , Huang Eng-Shang
Published: January 2020

The physical map for the genome of
Spodoptera frugiperda
nuclear polyhedrosis virus was constructed for restriction endonucleases
Bam
HI and
Hin
dIII. The ordering of the restriction fragments was accomplished by cross-blot hybridization of
Bam
HI,
Hin
dIII, and
Eco
RI fragments. The alignment of the
Hin
dIII fragments within the
Bam
HI map was achieved by double digestion with the two restriction endonucleases followed by cross-blot hybridization. The results showed that the viral genome consisted of mainly unique sequences. In addition, the circular nature of the viral genome was reaffirmed.
Small Reovirus Particles Composed Solely of Sigma NS with Specificity for Binding Different Nucleic Acids
Authors: Gomatos Peter J. , Prakash Om , Stamatos Nicholas M.
Published: January 2020

We reported previously that polycytidylate [poly(C)]-dependent RNA polymerase activity was a property of small spherical or triangular reovirus-specific particles which sedimented at 13 to 19S and were composed solely of the reovirus protein, sigma NS. Depending on the fraction of cellular extracts from which they were obtained, these particles exhibited marked differences in stability. Most 13 to 19S particles from a particular fraction repeatedly disaggregated into smaller 4 to 5S subunits with no enzymatic activity. Disruption of many particles could be prevented and polymerase activity retained after these particles had bound different single-stranded (ss) RNAs. Our previous results indicated that there was heterogeneity among the 13 to 19S particles in that possession of poly(C)-dependent RNA polymerase activity was a property of only some. Support for this heterogeneity was derived from the demonstration in this report that there were at least three types of binding sites present within particles in any purified preparation: (i) those binding only poly(C); (ii) those binding only reovirus ss RNAs; and (iii) those binding one or the other, but not both at the same time. It is suggested that only those particles able to bind either poly(C) or reovirus ss RNAs had poly(C)-dependent RNA polymerase activity, as reovirus ss RNAs markedly inhibited the polymerase activity. All three size classes of reovirus ss RNAs were equally effective in binding, but once bound, they were not copied. It is possible that heterogeneity in binding capacity of different particles comprised of only one protein, sigma NS, could result from the ability of subunits containing this protein to assemble into slightly different 13 to 19S particles with specificity of binding or polymerase activity conferred by the configuration of the assembled particles. The high capacity of sigma NS to bind many different nucleic acids with some specificity suggests that these particles may act during infection as condensing agents to bring together 10 reovirus ss RNA templates in preparation for double-stranded RNA synthesis.
Chromosomal localization of three endogenous retrovirus loci associated with virus production in White Leghorn chickens
Authors: Tereba A , Crittenden L B , Astrin S M
Published: January 2020

Proposed mechanisms for the generation of endogenous retrovirus loci have been examined by determining the chromosomal distribution of these loci by means of in situ hybridization. Unlike the clustering on chromosome 1 of five endogenous retrovirus loci associated with the gs- chf- phenotype A. Tereba and S. M. Astrin, submitted for publication), three loci associated with endogenous retrovirus production (V+ phenotype) were located on three separate chromosomes. ev2, which codes for the prototype endogenous RAV-0 genome in line 7(2) chickens, was localized near the middle of the long arm of chromosome 2, ev7, coding for a noninfectious, inducible genome present in line 15B chickens, was located near the end of the long arm of the Z chromosome. A third V+ locus, designated ev14, was detected near the middle of chromosome 3. This arrangement of V+ loci is consistent with an integration mechanism employing randomly distributed integration sites in the chicken genome. In addition, these data provide evidence suggesting that the gs- chf- -associated loci may have been generated by a different mechanism.
Polyoma Virus Infection of Retinoic Acid-Induced Differentiated Teratocarcinoma Cells
Authors: Fujimura Frank K. , Silbert Pamela E. , Eckhart Walter , Linney Elwood
Published: January 2020

The mouse teratocarcinoma stem cell line, F9, becomes permissive for productive polyoma infection upon treatment with retinoic acid. Through the use of M13-polyoma recombinant single-stranded DNA probes, spliced and unspliced early viral RNA were detected after polyoma infection of retinoic acid-treated and untreated F9 cultures.
Genetic complementation by cloned bacteriophage T4 late genes
Authors: Jacobs K A , Albright L M , Shibata D K , Geiduschek E P
Published: January 2020

Bacteriophage T4 containing nonsense mutations in late genes was found to be genetically complemented by four conjugate T4 genes (7, 11, 23, or 24) located on plasmid or phage vectors. Complementation was at a very low level unless the infecting phage carried a denB mutation (which abolishes T4 DNA endonuclease IV activity). In most experiments, the infecting phage also had a denA mutation, which abolishes T4 DNA endonuclease II activity. Mutations in the alc/unf gene (which allow dCMP-containing T4 late genes to be expressed) further increased complementation efficiency. Most of the alc/unf mutant phage strains used for these experiments were constructed to incorporate a gene 56 mutation, which blocks dCTP breakdown and allows replication to generate dCMP-containing T4 DNA. Effects of the alc/unf:56 mutant combination on complementation efficiency varied among the different T4 late genes. Despite regions of homology, ranging from 2 to 14 kilobase pairs, between cloned T4 genes and infecting genomes, the rate of formation of recombinants after T4 den:alc phage infection was generally low (higher for two mutants in gene 23, lower for mutants in gene 7 and 11). More significantly, when gene 23 complementation had to be preceded by recombination, the complementation efficiency was drastically reduced. We conclude that high complementation efficiency of cloned T4 late genes need not depend on prior complete breakage-reunion events which transpose those genes from the resident plasmid to a late promoter on the infecting T4 genome. The presence of the intact gene 23 on plasmids reduced the yield of T4 phage. The magnitude of this negative complementation effect varied in different plasmids; in the extreme case (plasmid pLA3), an almost 10-fold reduction of yield was observed. The cells can thus be said to have been made partly nonpermissive for this lytic virus by incorporating a part of the viral genome.
Alterations to controls of cellular DNA synthesis by adenovirus infection
Authors: Braithwaite A W , Murray J D , Bellett A J
Published: January 2020

Human adenovirus type 5 and temperature-sensitive mutants ts36, ts37, and ts125 induced cellular DNA synthesis in quiescent rodent cells at both permissive and nonpermissive temperatures. Cellular DNA synthesis induced by adenovirus type 5 or by serum required protein synthesis for both initiation and continuation, whereas viral DNA synthesis was not dependent upon continued protein synthesis once it was initiated. Both cellular and viral DNA replication was induced in adenovirus type 5-infected cells in the presence of dibutyryl cyclic AMP at concentrations which inhibited induction by serum which suggested that some of the controls of DNA synthesis in serum-treated and virus-infected cells are different. After adenovirus infection of quiescent cells, there was a decrease in the number of cells with G1 DNA content and an increase in cells with G2 diploid and greater DNA contents. Thus, adenovirus type 5 induces a complete round of cellular DNA replication, but in some cells, it induces a second round without completion of a normal mitosis. These results suggest that adenovirus type 5 is able to alter cell growth cycle controls in a way which may be related to its ability to transform cells.
Poliovirus morphogenesis. I. Identification of 80S dissociable particles and evidence for the artifactual production of procapsids
Authors: Marongiu M E , Pani A , Corrias M V , Sau M , La Colla P
Published: January 2020

The current model of poliovirus morphogenesis postulates a fundamental role for procapsid, 80S shells that, upon interaction with viral RNA and subsequent proteolytic cleavage, give rise to complete virus particles. Although 80S sedimenting particles can, indeed, be isolated from cytoplasmic extracts of infected cells, their physical properties differ from those reported for procapsids. Far from being stable structures, they can be dissociated by pH 8.5 and 0.1% sodium dodecyl sulfate into slower-sedimenting subunits. The reasons for this discrepancy were investigated, and two main modalities leading to the appearance of procapsids in vitro were identified. The first involves a temperature-mediated conversion of dissociable 80S particles into stable 80S procapsids, and the second involves the self-assembly of endogenous 14S subunits, also primed by an increase in the temperature of cytoplasmic extracts.
Enhanced Mutability Associated with a Temperature-Sensitive Mutant of Vesicular Stomatitis Virus
Authors: Pringle C. R. , Devine V. , Wilkie M. , Preston C. M. , Dolan A. , McGeoch D. J.
Published: January 2020

Temperature-sensitive (
ts
) mutant
ts
D1 of vesicular stomatitis virus, New Jersey serotype, is the sole representative of complementation group D. Clones derived from this mutant exhibited three different phenotypes with respect to electrophoretic mobility of the G and N polypeptides of the virion in sodium dodecyl sulfate-polyacrylamide gel. Analysis of non-
ts
pseudorevertants showed that none of the three phenotypes was associated with the temperature sensitivity of mutant
ts
D1. Additional phenotypes, some also involving the NS polypeptide, appeared during sequential cloning, indicating that mutations were generated at high frequency during replication of
ts
D1. Furthermore, mutations altering the electrophoretic mobility of the G, N, NS, and M polypeptides were induced in heterologous viruses multiplying in the same cells as
ts
D1. These heterologous viruses included another complementing
ts
mutant of vesicular stomatitis virus New Jersey and
ts
mutants of vesicular stomatitis virus Indiana and Chandipura virus. Complete or incomplete virions of
ts
D1 appeared to be equally efficient inducers of mutations in heterologous viruses. Analysis of the progeny of a mixed infection of two complementing
ts
mutants of vesicular stomatitis virus New Jersey with electrophoretically distinguishable G, N, NS, and M proteins yielded no recombinants and excluded recombination as a factor in the generation of the electrophoretic mobility variants. In vitro translation of total cytoplasmic RNA from BHK cells indicated that post-translational processing was not responsible for the aberrant electrophoretic mobility of the N, NS, and M protein mutants. Aberrant glycosylation could account for three of four G protein mutants, however. Some clones of
ts
D1 had an N polypeptide which migrated faster in sodium dodecyl sulfate-polyacrylamide gel than did the wild type, suggesting that the polypeptide might be shorter by about 10 amino acids. Determination of the nucleotide sequence to about 200 residues from each terminus of the
N
gene of one of these clones, a revertant, and the wild-type parent revealed no changes compatible with synthesis of a shorter polypeptide by premature termination or late initiation of translation. The sequence data indicated, however, that the N-protein mutant and its revertant differed from the parental wild type in two of the 399 nucleotides determined. These sequencing results and the phenomenon of enhanced mutability associated with mutant
ts
D1 reveal that rapid and extensive evolution of the viral genome can occur during the course of normal cytolytic infection of cultured cells.
Expression of murine leukemia viruses in the highly lymphomatous BXH-2 recombinant inbred mouse strain
Authors: Bedigian H G , Taylor B A , Meier H
Published: January 2020

Among 12 recombinant inbred strains of mice derived from crossing two strains, C57BL/6J and C3H/HeJ, which have a low incidence of neoplastic disease, one strain (BXH-2) has been found to have a high incidence of lymphoma, of non-T-cell origin, at an early age. The BXH-2 strain carries the Fv-1b allele and spontaneously expresses a B-tropic murine leukemia virus beginning at as early as 10 days of gestation and continuing throughout their life. No significant differences in ecotropic virus titers were observed at any age tested (16 to 17 days of gestation through 7 months), whereas xenotropic virus was first detected in lymphoid tissues of 2-month-old mice and virus titers increased with age. Dual tropic virus(es), which induced cytopathic changes on mink lung cells, was isolated from BXH-2 lymphomatous tissues. Unlike AKR mink lung focus-forming virus (N-tropic recombinant), BXH-2 dual tropic virus is B tropic and induces cytopathic changes in mouse fibroblast cultures as well. The BXH-2 mouse provides a model system for studying the role of replication-competent viruses in spontaneously occurring leukemias of non-T-cell lineage and neurological disease.
Mouse hepatitis virus A59: mRNA structure and genetic localization of the sequence divergence from hepatotropic strain MHV-3
Authors: Lai M M , Brayton P R , Armen R C , Patton C D , Pugh C , Stohlman S A
Published: January 2020

The composition and structure of the mouse hepatitis virus (MHV)-specific RNA in actinomycin D-treated, infected L-2 cells were studied. SEven virus-specific RNA species with molecular weights of 0.6 X 10(6), 0.9 X 10(6), 1.2 X 10(6), 1.5 X 10(6), 3.0 X 10(6), 4.0 X 10(6), and 5.4 X 10(6) (equivalent to the viral genome) were detected. T1 oligonucleotide fingerprinting studies suggested that the sequences of each RNA species were totally included within the next large RNa species. The oligonucleotides of each RNA species were mapped on the 60S RNA genome of the virus. Each RNA species contained the oligonucleotides starting from the 3' end of the genome and extending continuously for various lengths in the 3' leads to 5' direction. All of the viral RNA species contained a polyadenylate stretch of 100 to 130 nucleotides and probably identical sequences immediately next to the polyadenylate. These data suggested that the virus-specific RNAs are mRNA's and have a stairlike structure similar to that of infectious bronchitis virus, an avian coronavirus. A proposal is presented, based on the mRNA structure, for the designation of the genes on the MHV genome. Using this proposal, the sequence differences between A59, a weakly pathogenic strain, and MHV-3, a strongly hepatotropic strain, were localized primarily in mRNA's 1 and 3, corresponding t genes A and C.
Mechanism of Transfection with Deoxyribonucleic Acid from the Temperate
Bacillus
Bacteriophage φ105
Authors: Rutberg Lars , Hoch James A. , Spizizen John
Published: January 2020

Bacteriophage φ105 is a temperate phage for the transformable
Bacillus subtilis
168. The infectivity of deoxyribonucleic acid (DNA) extracted from mature φ105 phage particles, from bacteria lysogenic for φ105 (prophage DNA), and from induced lysogenic bacteria (vegetative DNA) was examined in the
B. subtilis
transformation system. About one infectious center was formed per 10
8
mature DNA molecules added to competent cells, but single markers could be rescued from mature DNA by a superinfecting phage at a 10
3
- to 10
4
-fold higher frequency. Single markers in mature DNA were inactivated at an exponential rate after uptake by a competent cell. Prophage and vegetative DNA gave about one infectious center per 10
3
molecules added to competent cells. Infectious prophage DNA entered competent cells as a single molecule; it gave a majority of lytic responses. Single markers in sheared prophage DNA were inactivated at the same rate as markers in mature DNA. Prophage DNA was dependent on the bacterial
rec-1
function for its infectivity, whereas vegetative DNA was not. The mechanism of transfection of
B. subtilis
with viral DNA is discussed, and a model for transfection with φ105 DNA is proposed.
Fate of Sendai Virus Ribonucleoprotein in Virus-infected Cells
Authors: Bukrinskaya A. G. , Zhdanov V. M. , Vorkunova G. K.
Published: January 2020

The cytoplasmic extracts of Ehrlich ascites tumor cells infected with
32
PO
4
and
3
H-leucine-labeled Sendai virus have been examined during the course of infection with respect to sedimentation behavior and buoyant densities of input virus radioactivity. It was found that
32
P and
3
H radioactivities were coincident, and, at 30 min after infection, the bulk of radioactivity was recovered in the polysome region of a sucrose gradient in the position of Sendai virus ribonucleoprotein (210
S
). The heterogeneity of radioactivity profiles appeared at 1 hr after infection and increased during 6 hr of incubation. The buoyant densities of input virus components were determined by banding in CsCl gradient. Here again the bulk of coincident
32
P and
3
H radioactivity at 30 min after infection banded at the same density as Sendai virus ribonucleoprotein (1.31 g/cm
3
.) This component disappeared at 3 hr after infection, and
32
P and
3
H radioactivities were now found in components banded at densities 1.38, 1.41, 1.45, 1.49, and 1.55 g/cm
3
. The results presented are consistent with the idea that virus ribonucleoprotein is retained in the cytoplasm of infected cells during at least 6 hr of incubation, being partly deproteinized in the course of infection. The nature of components which banded at ρ = 1.41, 1.45, 1.49, and 1.55 as complexes of partly deproteinized ribonucleoprotein with ribosomes will be described in a separate paper.
Relative Sensitivities of Viruses to Different Species of Interferon
Authors: Stewart William E. , Scott Woodie D. , Sulkin S. Edward
Published: January 2020

Some viruses were found to be more sensitive than others to the action of interferons from certain species of animals but less sensitive to interferons from other species. Vaccinia virus was the most sensitive to mouse and hamster interferons of five viruses tested, but the least sensitive of these five viruses to human, rabbit, and bat interferons. The relative sensitivities of the viruses to interferons were found to be characteristic for each of the species tested, with those closely related phylogenetically exhibiting similar patterns of relative interferon-induced virus resistance. The amount of synthetic double-stranded polynucleotide polyinosinic acid-polycytidylic acid required to induce resistance to each of the viruses in each of the cell species correlated with the interferon sensitivities of the viruses.
Poliovirus-induced Cellular Injury
Authors: Blackman Kenneth E. , Bubel H. Curt
Published: January 2020

Protein leakage was used as a quantitative measure of poliovirus-induced cellular injury under suspended cell culture conditions. The requirements for protein leakage were studied in detail and it was established that events early in the infectious cycle which depend upon viral protein synthesis were responsible for cell damage. Extralysosomal β-glucuronidase appeared in infected cells before the onset of protein leakage and release of newly synthesized virus. Hydrocortisone treatment of infected cells resulted in only a slight delay in the release of β-glucuronidase from lysosomes and protein and virus from cells. These results suggest that events associated with poliovirus synthesis trigger the release of lysosomal hydrolases which in turn injure the plasma membrane, allowing cytoplasmic proteins and virus to leak out of the cell.
Lysogenic Conversion in
Bacillus amyloliquefaciens
H Affecting Viral Adsorption
Authors: Jonasson Jon , Rutberg Lars , Young Frank E.
Published: January 2020

Lysogenization of
Bacillus amyloliquefaciens
H with bacteriophage PK renders the bacteria resistant to superinfection with bacteriophage of PK type.
Reaction of Chick Embryo Cells Infected with Leukosis Strain MC29 Virus with Fluorescein-Labeled Antibody
Authors: Fritz Robert B. , Langlois A. J. , Beard J. W.
Published: January 2020

Immune serum was prepared in the rabbit with BAI strain A leukosis virus isolated by centrifugal fractionation from the plasma of chickens with myeloblastic leukemia and further purified on a potassium tartrate gradient. Antibody to group-specific antigen was demonstrated in the serum by immunoelectrophoresis and immunodiffusion. Fluorescein-conjugated serum was used unabsorbed and absorbed with chick cells for study of acetone-fixed chick embryo cells uninfected or infected with strain MC29 avian leukosis virus. With unabsorbed serum, large numbers of cytoplasmic particles stained in a few cells within 2 hr after exposure to virus, and the cell number increased greatly in 24 hr. Absorption of the serum abolished the early reaction. Staining with absorbed serum was delayed until about 14 hr after culture exposure to virus, but essentially all cells were stained within 72 hr at the time when all cells were morphologically altered. Differences between the responses to unabsorbed and absorbed serum suggested cytoplasmic formation or concentration of chick tissue antigen similar to that incorporated in leukosis virus particles. The characteristics of staining with absorbed serum were similar to those observed by others in analogous studies with avian tumor viruses.
Influence of Diethylaminoethyl-Dextran on Uptake and Degradation of Polyoma Virus Deoxyribonucleic Acid by Mouse Embryo Cells
Authors: Warden D. , Thorne H. V.
Published: January 2020

The uptake of
32
P-labeled polyoma virus deoxyribonucleic acid (DNA) (I and II + III) by mouse embryo cells was increased from two- to fivefold in the presence of 500 μg of diethylaminoethyl-dextran (DEAE-D) per ml. This concentration of DEAE-D gives maximal enhancement of infectivity; however, the increase is many thousand-fold. As the DEAE-D concentration was increased from 0 μg/ml, uptake and infectivity increased to flat maxima and then decreased in a similar manner, except that at low DEAE-D concentrations uptake was relatively much greater than infectivity. Several other polycations also increased DNA uptake but did not enhance infectivity, and uptake of viral DNA was unaffected by the presence of mouse DNA, although infectivity was reduced. Thus, increased uptake is not the sole basis for the enhancement of infectivity produced by DEAE-D. The possibilities that DNA complexed with DEAE-D penetrates more rapidly or is stabilized against degradation do not completely account for enhancement since complexes formed in mixtures of DNA and DEAE-D, which sedimented heterogeneously from 40 to 60
S
, were infectious only for monolayers treated with DEAE-D. A more likely factor in enhancement is inhibition of the cellular nuclease activity detected, since virus DNA exposed to cells was much more degraded in the absence than in the presence of DEAE-D. The nuclease activity produced single-strand breaks in double-stranded DNA. Treatment of monolayers with deoxyribonuclease after adsorption of DNA in the presence of DEAE-D reduced cell-associated radioactivity by about 70%, although the number of plaques formed was not affected. In the absence of DEAE-D, 90 to 100% was removed by deoxyribonuclease. Thus, in both cases most of the DNA was adsorbed extracellularly. The greater deoxyribonuclease-resistant fraction in the presence of DEAE-D would be consistent with another possibility: that enhancement results from an increase in DNA penetration rate due to some action of DEAE-D on the cell.
Synthesis of Replicative Form Deoxyribonucleic Acid and Messenger Ribonucleic Acid by Gene IV Mutants of Bacteriophage S13
Authors: Shleser Robert , Puga Alvaro , Tessman Ethel S.
Published: January 2020

Gene IV mutants of bacteriophage S13 are known to be blocked in infectious replicative form (RF) DNA synthesis, producing only a small fraction of the RF formed by wild-type phage. This investigation shows that gene IV mutants form only parental RF and are blocked in the synthesis of any progeny RF, either infectious or noninfectious. This was determined by density labeling of RF in cells treated with mitomycin C to suppress host deoxyribonucleic acid (DNA) synthesis. RF synthesis was also studied in untreated cells, using methylated albumin columns to separate RF from host DNA. In this case it was also found that synthesis of progeny RF by gene IV mutants is negligible. It has been found by DNA-ribonucleic acid (RNA) hybridization experiments that gene IV mutants form at least as much or more messenger RNA than wild-type phage. Therefore, parental RF alone can form messenger RNA in appreciable amounts.