bluuebunny/crossref_metadata_2025 huggingface dataset:
Anatomy of herpes simplex virus DNA VII. alpha-RNA is homologous to noncontiguous sites in both the L and S components of viral DNA
Authors: Jones P C , Hayward G S , Roizman B
Published: January 2020

Previous reports from this laboratory (Honess and Roizman, 1974) have operationally defined alpha polypeptides as the viral proteins that are synthesized first in HEp-2 cells treated with cycloheximide from the time of infection with herpes simplex virus type 1 until the withdrawal of the drug 12 to 15 h after infection. It has also been shown that the viral RNA (designated alpha RNA) that accumulates in the cytoplasm during cycloheximide treatment and on polyribosomes immediately upon withdrawal of the drug is homologous to 10 to 12% of viral DNA, whereas the viral RNA accumulating in the cytoplasm of untreated cells at 8 to 14 h after infection is homologous to 43% of viral DNA (Kozak and Roizman, 1974). In the present study, alpha RNA and cytoplasmic RNA extracted from untreated cells 8 h after infection were each hybridized in liquid to in vitro labeled restriction endonuclease fragments generated by cleavage of herpes simplex virus type 1 DNA with Hsu I, with Bgl II, and with both enzymes simultaneously. The data show that only a subset of the fragments hybridized to alpha RNA, and these are scattered within both the L and S components of the DNA. There are at least five noncontiguous regions in the DNA homologous to alpha RNA; two of these are located partially within the reiterated sequences in the S component. All fragments tested hybridized more extensively with 8-h cytoplasmic RNA than with alpha RNA. Four adjacent fragments, corresponding to 30% of the DNA and mapping within the L component, hybridized exclusively with the cytoplasmic RNA extracted from cells 8 h after infection.
Complementation analysis of measles virus temperature-sensitive mutants
Authors: Breschkin A M , Rapp F , Payne F E
Published: January 2020

Two sets of independently isolated measles virus temperature-sensitive mutants were quantitatively tested for complementation. Analysis of the nine possible combinations of representative mutants indicated that only one pair of mutants is noncomplementing. Thus, the measles virus mutants studied to date define five complementation groups.
Temperate Bacillus subtilis bacteriophage phi 3T: chromosomal attachment site and comparison with temperate bacteriophages phi 105 and SPO2
Authors: Williams M T , Young F E
Published: January 2020

The temperate Bacillus subtilis bacteriophage phi 3T contains within its genome a locus, designated thyP3, that encodes for a protein with thymidylate synthetase activity. Bacteriophage phi 3T is different from the two previously characterized temperate phages, phi 105 and SPO2, in: heteroimmunity, response to bacteriophage antisera, endonuclease digestion pattern, induction in the presence of 6-(p-hydroxyphenylazo)-uracil, and effect on the lytic cycle of bacteriophage phi 1. The mean burst size of phi 3T is 56. The dose response curve with bacteriophage phi 3T DNA is linear for transfection and transformation to the Thy+ phenotype. The inserted prophage has been mapped by PBS1 transduction; it is between chromosomal markers ilvA8 and gltA in the terminus of the chromosome. Thus thyP3 maps at a site separate from, but between, the bacterial markers thyA and thyB when thyP3 is in the prophage state.
Replication process of the parvovirus H-1. VIII. Partial denaturation mapping and localization of the replication origin of H-1 replicative-form DNA with electron microscopy
Authors: Singer I I , Rhode S L
Published: January 2020

Partial denaturation mapping, restriction endonuclease digestion, and electron microscopy were used to determine which end of the linear duplex replicative-form (RF) DNA molecule contains the origin of RF replication for the parvovirus H-1. This origin was localized within approximately 300 base pairs of the arbitrarily designated right end of the RF DNA, in the EcoRI or HaeII-A fragment. Based on denaturation behavior in formamide, the right end was also found to have a relatively high guanine plus cytosine content, whereas the region adjacent to the left terminus of the RF DNA molecule was adenine plus thymine rich.
Rifampin and vaccinia DNA
Authors: Esteban M
Published: January 2020

The effect of rifampin on the replication of vaccinia DNA was studied in mouse L cells by a cytochemical techinque and by alkaline sucrose sedimentation analysis of newly synthesized viral DNA molecules. By the use of a fluorescent DNA-binding compound (Hoechst 33258), the sequential appearance, size, and location of the viral "factories" in rifampin-treated, virus-infected cells were found to be indistinguishable from those observed in untreated, infected cells. Sedimentation analysis in alkaline scurose gradients of the viral DNA molecules labeled in pulse-chase experiments showed that formation of small fragments, elongation into "intermediate"-sized molecules, and maturation into full-length viral DNA and, finally, into cross-linked viral DNA molecules occurred in the absence or presence of rifampin. The results support the view that the primary effect of the drug is related to assembly or morphogenesis.
Electron microscopy of late adenovirus type 2 mRNA hybridized to double-stranded viral DNA
Authors: Meyer J , Neuwald P D , Lai S P , Maizel J V , Westphal H
Published: January 2020

R loops were generated with late adenovirus type 2 (Ad2) mRNA in double-stranded viral DNA, and visualized by electron microscopy. Unpaired DNA sequences in Ad2:Ad2+ND4 heteroduplex DNA served as a visual marker for the orientation of R loops with respect to the conventional DNA map. The most abundant classes of late Ad2 mRNA observed by this technique hybridized, in order of R-loop frequency, with midpoints near posit1ons 0.57, 0.88, 0.77, and 0.40 to 0.50 of the DNA map. The R loop at position 0.57, 0.88, 0.77, and 0.40 containing the hexon gene; the one at position 0.88 corresponded to a region containing the fiber gene. The relative frequencies of these two R loops paralleled those of the encoded gene products. The mRNA sizes, calculated from those of the respective R loops, were slightly larger than needed to code for these polypeptides. Using the R-loop technique, two locations at which adjacent mRNA's hybridized to different strands were accurately mapped at positions 0.61 and 0.91 of the DNA. The map positions of late Ad2 mRNA correlated well to published RNA and protein maps.
Biochemical studies on a reovirus-like agent (rotovirus) from lambs
Authors: Todd D , McNulty M S
Published: January 2020

Ten polypeptides were detected in double-capsid lamb rotavirus; four of these appeared to be associated with the outer capsid. Lamb rotavirus RNA, which consisted of 11 or 12 segments, differed from pig rotavirus RNA in the electrophoretic mibility of one of the genome segments.
Biological and biochemical studies of cells transformed by simian virus 40 temperature-sensitive gene A mutants and A mutant revertants
Authors: Tenen D G , Martin R G , Anderson J , Livingston D M
Published: January 2020

The growth properties of hamster cells transformed by wild-type Simian virus 40 (SV40), by early SV40 temperature-sensitive mutants of the A complementation group, and by spontaneous revertants of these mutants were studied. All of the tsA mutant-transformed cells were temperature sensitive in their ability to form clones in soft agar and on monolayers of normal cells except for CHLA-30L1, which was not temperature sensitive in the latter property. All cells transformed by stable revertants of well-characterized tsA mutants possessed certain growth properties in common with wild-type-transformed cells at both temperatures. Virus rescued from tsA transformants including CHLA30L1 was temperature sensitive for viral DNA replication, whereas that rescued from revertant and wild-type transformants was not thermolabile in this regard. T antigen present in crude extracts of tsA-transformed cells including CHLA30L1, grown at 33 degreeC, was temperature sensitive by in vitro immunoassay, whereas that from wild-type-transformed cells was relatively stable. T antigen from revertant transformants was more stable than the tsA protein. Partially purified T antigen from revertant-transformed cells was nearly as stable as wild-type antigen in its ability to bind DNA after heating at 44 degrees C, whereas T antigen from tsA30 mutant-transformed cells was relatively thermolabile. These results further indicate that T antigen is a product of the SV40 A gene. Significantly more T antigen was found in extracts of CHLA30L1 grown to high density at the nonpermissive temperature than in any other tsA-transformed cell similarly grown. This is consistent with the suggestion that the amount of T antigen synthesized in CHLA30L1 is large enoughto allow partial expression of the transformed phenotype at the restrictive temperature. Alternatively, the increase in T antigen concentration may be secondary to one or more genetic alterations that independently affect the transformed phenotype of these cells.
Inverted repetition in the chromosome of pseudorabies virus
Authors: Stevely W S
Published: January 2020

An electron microscope examination of pseudorabies virus DNA single strands after self-annealing shows a loop of single-stranded DNA at one end of the molecule contiguous to a double-strand region. The molecule then terminates in a further single-stranded region that does not form a loop. It is suggested that the DNA contains a sequence of 13.3 x 106 daltons at one end, which is repeated internally with opposite polarity. The segment of the genome separating the repeats has a double-strand molecular weight of 5.4 x 106. The whole native DNA has a molecular weight of 90 x 106 to 95 x 106.
Genetic studies of the ploidy of Moloney murine leukemia virus
Authors: McCarter J A
Published: January 2020

An assay for Moloney murine leukemia virus was developed that made use of the production of morphologically altered foci in nonproducer mouse cells (15F) carrying murine sarcoma virus. Wild-type (wt) virus gave a ratio of titers at 39 degrees C/34degrees C = 1.05 +/- 0.45 (standard deviation;n = 20). A spontaneous, thermosensitive (ts) mutant of Moloney murine leukemia virus, ts3, defective in a late viral function, gave 39 degrees C/34degrees C = 0. A murine cell line (TB) was mixedly infected with ts3 and wt (multiplicities of infection, 7.8:4.3), cloned after infection, and shown to be infected by both viruses. At 34 degrees C it produced wt, ts, and particles of mixed parentage. The heterozygotes (hz) had ratios of assays 39 degrees C/34 degrees C = 0.06 to 0.84 (mean, 0.36). To eliminate possible interference by multiploid particles with determination of the proportions of the three types of particles, the virus produced by the mixedly infected, cloned cell line at 34 degrees C was distributed by velocity sedimentation in a sucrose gradient, and virus was picked from the lightest part of the gradient. The proportions of ts, wt, and hz were 0.27, 0.26, and 0.47. Those particles identified as hz segreated ts, wt, and hz in the proportions 0.24, 0.27, and 0.49, respectively. These values were not significantly different from those predicted from a diploid model of the genome.
Cell cycle dependency of murine cytomegalovirus replication in synchronized 3T3 cells
Authors: Muller M T , Hudson J B
Published: January 2020

Synchronized murine 3T3 cells have been used to investigate the possible dependency of murine cytomegalovirus replication upon the cell cycle. The normal latent period of 12 h characteristic of asynchronous 3T3 cells was protracted to more than 24 h after an early G1 infection in synchronous cells. In this case viral progeny were not detected until after the initiation of the host S-phase. Cells maintained in the G1 phase did not replicate virus. This failure could not be explained by a decrease in virus penetration but was apparently due to a requirement for an event associated with the host S-phase. Thymidine-induced inhibition of cell cycle traverse also blocked virus replication. Viral DNA synthesis did not initiate until after the initiation of host DNA. In contrast, herpes simplex virus type 1 replicated in 3T3 cells independently of the cell cycle.
Replication process of the parvovirus H-1. IX. Physical mapping studies of the H-1 genome
Authors: Rhode S L
Published: January 2020

The cleavage map of H-1 replicative-form DNA to the bacterial restriction endonuclease EcoRI, HaeII, HaeIII, HindII, HindIII, and HpaII has been determined. The 5'-phosphoryl end of the viral strand is on the right end of the molecule at or near the replication origin. Evidence is presented for the presence of inverted self-complementary sequences at the right end that differ from those at the left end. These sequences allow a foldback of the DNA after denaturation, and a minority of the native replicative-form DNA has the foldback configuration. The possible role of these structures in H-1 DNA synthesis is discussed.
Immunofluorescence Study of the Adenovirus Type 2 Single-Stranded DNA Binding Protein in Infected and Transformed Cells
Authors: Sugawara Kenji , Gilead Zvee , Wold William S. M. , Green Maurice
Published: January 2020

High-titer monospecific antiserum against highly purified adenovirus 2 (Ad2) single-stranded DNA binding protein (DBP) was used to study, by indirect immunofluorescence (IF), the synthesis of DBP in Ad2-infected human cells and adenovirus-transformed rat, hamster, and human cell lines. In infected cells the synthesis of DBP was first detected in the cytoplasm at 2 to 4 h postinfection and reached a maximum intensity at 6 h postinfection. At this time DBP began to accumulate in the nucleus, where it reached maximum intensity at about 14 h postinfection. The cytoplasmic IF was diffuse, whereas nuclear IF appeared as dots that coalesced into large globules as infection progressed. In cells treated with 1-β-
d
-arabinofuranosylcytosine to inhibit viral DNA synthesis, strong nuclear IF was observed in the form of dots, but the large fluorescent globules were not observed. The Ad2 (oncogenic group C) anti-DBP serum reacted very strongly by IF with Ad5 (group C)-infected, to a lesser extent with Ad7 and Ad11 (group B)-infected, and weakly with Ad12 and Ad18 (group A)-infected KB cells (treated with 1-β-
d
-arabinofuranosylcytosine). These results may indicate that Ad2 DBP is closely related immunologically to DBPs induced early after infection by adenovirus serotypes in oncogenic group C, moderately related to DBPs of serotypes in oncogenic group B, and perhaps distantly related to DBPs of serotypes in oncogenic group A. The following adenovirus-transformed cell lines were examined for DBP synthesis by IF with the Ad2 anti-DBP serum: six rat cell lines (T2C4, F17, 8662, 8638, 8617, and F161) transformed by Ad2 virus, three hamster cell lines transformed by Ad2 virus (Ad2HT1) and Ad2-simian virus 40 hybrid virus (ND1HK1 and ND4HK4), and one rat (5RK) and one human (293-31) cell line transformed by transfection with Ad5 DNA. T2C4 and 8662 appeared weakly positive, whereas Ad2HT1 and ND4HK1 were strongly positive. The other transformed cell lines did not produce DBP detectable by IF. Thus, some but not all transformed cell lines produce DBP, which indicates that DBP is not required for maintenance of cell transformation and that transformed cells can express “nontransforming” viral genes as protein.
Alteration of the Escherichia coli membrane by addition of bacteriophage T4 protein synthesized after infection
Authors: Ennis H L , Kievitt K D
Published: January 2020

Many T4-induced proteins were found associated with the Escherichia coli membrane during infection. Some of these were apparently ionically bound, but many could be identified as integral parts of the inner and outer bacterial membranes by their selective solubilities in guanidine or Sarkosyl. The synthesis and insertion of these proteins into the bacterial membrane were temporally controlled and, once in the membrane, these proteins were stably integrated. Host membrane protein synthesis continued after infection of non-UV-irradiated cells, but was not present, if the cells were irradiated. There were no major redistribution or loss of bacterial proteins from E. coli membranes as a consequence of T4 infection.
Virus-directed post-translational cleavage in Sindbus virus-infected cells
Authors: Schupham R K , Jones K J , Sagik B P , Bose H R
Published: January 2020

The viral polypeptides synthesized in cells coinfected with group C and group D or E Sindbis virus mutants were studied. Cleavage of the ts2 protein occurs in cells coinfected with ts2 and ts20. Since the ts2 protein fails to chase in cells infected with ts2 alone, the activity effecting this cleavage must be, at least in part, virus specified.
Antigenic characterization of flavivirus structural proteins separated by isoelectric focusing
Authors: Trent D W
Published: January 2020

Isoelectrofocusing of nonionic-detergent-disrupted flaviviruses separated the envelope glycoprotein of 53,000 to 58,000 daltons and the nucleocapsid protein of 14,000 daltons. The envelope protein and nucleocapsid protein were isolated at isoelectric points of pI 7.8 and 10.3, respectively. The antigenic determinants of St. Louis encephalitis, Japanese encephalitis, and dengue virus envelope and nucleocapsid proteins were examined by solid-phase competition radioimmunoassay. By the appropriate selection of antiserum and competing proteins, it was possible to distinguish type-specific, complex-reactive and flavivirus group-reactive antigenic determinants. The envelope glycoproteins of St. Louis encephalitis, Japanese encephalitis, and dengue viruses were found to contain each of these three classes of antigenic determinants. Most of the determinants on the envelope protein were type specific, some were complex reactive, and a small fraction were flavivirus group reactive. The nucleocapsid protein contained only flavivirus group-reactive antigenic determinants.
In vitro system that synthesizes circular viral DNA of bacteriophage phi X 174
Authors: Mukai R , Hayashi M
Published: January 2020

An extract prepared from Escherichia coli cells infected with phi chi 174 bacteriophage was capable of incorporating dTTP into phage-specific DNAs in vitro. The synthesized DNAs were associated with proteins and sedimented with S values of 20, 50, and 90 in a sucrose gradient sedimentation. DNA isolated from 20S material was open circular replicative form (RF), DNA in 50S material was replicative-form DNA with an extended single-stranded viral DNA that ranged up to one genome in length, and DNA in 90S material consisted of circular and linear single-stranded viral DNA of full genome length and single-stranded viral DNA shorter than full genome length. Pulse and pulse-chase experiments indicated that 90S material derived from 50S material.
Transduction of bacteriophage Mu by bacteriophage T1
Authors: Bendig M M , Drexler H
Published: January 2020

Phage T1 transduces phage Mu PFU from Mu-lysogenic donor cells to sensitive recipient cells. The efficiency of transduction depends on the chromosomal location of the Mu prophage. T1, therefore, appears to package different regions of the bacterial chromosome with different efficiencies. Although T1 transduces bacterial markers with different efficiencies, there is no direct correlation between the efficiency of transduction of a bacterial marker and the efficiency of transduction of Mu PFU from donor cells with the Mu prophage located in that marker.
Prophage F116: Evidence for Extrachromosomal Location in
Pseudomonas aeruginosa
Strain PAO
Authors: Miller Robert V. , Pemberton J. M. , Clark Alvin J.
Published: January 2020

F116 is a temperate-generalized transducing phage of
Pseudomonas aeruginosa.
Genetic evidence leads to the conclusion that F116 prophage DNA is maintained extrachromosomally as a plasmid. Preliminary physical evidence is presented to support this hypothesis.
Physiological State of Human Embryonic Lung Cells Affects Their Response to Human Cytomegalovirus
Authors: DeMarchi Jean M. , Kaplan Albert S.
Published: January 2020

Cultures of human embryonic lung (HEL) cells in different physiological states were studied for their susceptibility to infection with human cytomegalovirus (CMV) with respect to production of infectious virus, synthesis of viral antigens, and virus-induced stimulation of cellular DNA synthesis. In general, subconfluent, actively growing cells yielded higher amounts of infectious virus than did confluent contact-inhibited cells. The higher yield of infectious virus was correlated with a greater percentage of cells producing viral antigens within the first 48 h after infection. In confluent cultures, 25 to 50% of the cells produced viral antigens within the first 48 h postinfection. This proportion did not change over a 10-fold range of multiplicity of infection, indicating that many of the cells in confluent cultures did not support productive infection. However, virtually all the cells in subconfluent cultures were susceptible. Also, in contrast to herpes simplex virus and pseudorabies virus, infectious CMV is not produced by cells treated with 5-fluorouracil and thymidine. Virus-induced stimulation of cellular DNA synthesis in cells infected at high multiplicities of infection could be detected only in confluent cultures, in which cellular DNA synthesis had been previously suppressed, but could not be detected in similarly treated cultures of subconfluent cells. The lack of detectable stimulation of cellular DNA synthesis in the latter was related to the fact that practically all the cells in the culture synthesized viral antigens within the first 48 h after infection, productive infection and detectable synthesis of cellular DNA being mutually exclusive.
Squirrel monkey retrovirus: an endogenous virus of a new world primate
Authors: Colcher D , Heberling R L , Kalter S S , Schlom J
Published: January 2020

Squirrel monkey retrovirus (SMRV) was isolated by cocultivation of squirrel monkey lung cells with canine cells. 3H-labeled 60-70S SMRV RNA, isolated from virus grown in canine cells, hybridized to the same extent and to the same Cot1/2 value to the DNA of all tissues of all squirrel monkeys tested; Cot1/2 values show that SMRV proviral sequences are present in the low repetitive range. No SMRV proviral sequences were detected in tissues from a variety of other New World monkeys, Old World monkeys, or apes. Murine, feline, bovine, and canine cells also contain no detectable SMRV proviral sequences. Competitive molecular hybridization studies revealed no detectable sequence homology between the 60-70S RNAs of SMRV and Mason-Pfizer virus (MPV). The virion-associated DNA polymerase of SMRV is similar to that of MPV in that it has a molecular weight of approximately 80,000 and prefers magnesium as a divalent cation using oligo(dG)-poly(rC) as primer-template. The virion-associated DNA polymerase of SMRV can be clearly distinguished from those of MPV and the mouse mammary tumor viruses, however, by its preference for manganese as a divalent cation in the presence of high salt.
Characterization of a retravirus isolated from squirrel monkeys
Authors: Schochetman G , Fine D , Arthur L , Gilden R , Heberling R
Published: January 2020

A new retravirus (SMRV) isolated from a squirrel monkey, Saimiri sciureus, has an Mg2+-dependen reverse transcriptase and a buoyant density of 1.17 g/cm3 in sucrose and 1.21 g/cm3 in cesium chloride, similar to the mouse mammary tumor virus and the Mason-Pfizer monkey virus. The polypeptide patter of SMRV as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was distinct from the reported polypeptide patterns of known retraviruses. Four major polypeptides of molecular weights 40,000, 20,000, 14,000 and 8,000 were resolved in virus propagated in human, mink, and canine cells. In A204 human rhabdomyosarcoma cells, a protein of 73,000 daltons (gp73) represented the major viral glycoprotein as determined by [3H]glucosamine labeling. Additional proteins were also observed, but their presence depended on the cell type in which the virus was propagated. In both species-and interspecies-specific assays, no antigenic relatedness was observed between SMRV and Mason-Pfizer monkey virus, mouse mammary tumor virus, baboon endogenous virus (BaLV), woolly monkey virus (SSV-1), murine leukemia virus, endogenous feline type C virus (RD-114), bovine leukemia virus, and equine infectious anemia virus. These findings indicate that SMRV represents a new retravirus and the first isolate from a New World monkey.
DNA of Epstein-Barr Virus. II. Comparison of the Molecular Weights of Restriction Endonuclease Fragments of the DNA of Epstein-Barr Virus Strains and Identification of End Fragments of the B95-8 Strain
Authors: Hayward S. Diane , Kieff Elliott
Published: January 2020

Incubation of the DNA of the B95-8 strain of Epstein-Barr virus [EBV (B95-8) DNA] with
Eco
RI,
Hsu
I,
Sal
I, or
Kpn
I restriction endonuclease yielded 8 to 15 fragments separable on 0.4% agarose gels and ranging in molecular weight from less than 1 to more than 30 × 10
6
.
Bam
I and
Bgl
II yielded fragments smaller than 11 × 10
6
. Preincubation of EBV (B95-8) DNA with lambda exonuclease resulted in a decrease in the
Hsu
I A and
Sal
I A and D fragments, indicating that these fragments are positioned near termini. The electrophoretic profiles of the fragments produced by cleavage of the DNA of the B95-8, HR-1, and Jijoye strains of EBV were each distinctive. The molecular weights of some
Eco
RI,
Hsu
I, and
Sal
I fragments from the DNA of the HR-1 strain of EBV [EBV (HR-1) DNA] and of
Eco
RI fragments of the DNA of the Jijoye strain of EBV were identical to that of fragments produced by cleavage of EBV (B95-8) DNA with the same enzyme, whereas others were unique to each strain. Some
Hsu
I,
Eco
RI, and
Sal
I fragments of EBV (HR-1) DNA and
Kpn
I fragments of EBV (B95-8) DNA were present in half-molar abundance relative to the majority of the fragments. In these instances, the sum of the molecular weights of the fragments was in excess of 10
8
, the known molecular weight of EBV (HR-1) and (B95-8) DNA. The simplest interpretation of this finding is that each EBV (HR-1), and possibly also (B95-8), DNA preparation contains two populations of DNA molecules that differ in the arrangement of DNA sequences about a single point, such as has been described for herpes simplex virus DNA. Minor fragments could also be observed if there were more than one difference in primary structure of the DNAs. The data do not exclude more extensive heterogeneity in primary structure of the DNA of the HR-1 strain. However, the observation that the relative molar abundance of major and minor fragments of EBV (HR-1) DNA did not vary between preparations from cultures that had been maintained separately for several years favors the former hypothesis over the latter.
Two infectious forms of bacteriophage phi X 174
Authors: Fujisawa H , Hayashi M
Published: January 2020

Infectious particles with S values of 114 and 132 were isolated from cells infected with bacteriophage phi chi 174. Electron micrographs of the 132S particle revealed a spherical structure with a diameter of about 40 nm. The 114S particle had spikelike projections and a diameter of about 32 nm. The 132S particles could be converted to 114S particles in vitro. However, pulse and pulse-chase experiments indicated no precursor-product relationship between these two particles in vivo.
Biochemical and immunological characterization of the major envelope glycoprotein of bovine leukemia virus
Authors: Devare S G , Stephenson J R
Published: January 2020

The major envelope glycoprotein of bovine leukemia virus was isolated by lectin-bound Sepharose and DEAE-cellulose column chromatography. This protein was shown to have a molecular weight of about 41,000 and to lack detectable immunological cross-reactivity with glycoproteins of other oncornaviruses. Sera obtained from 100% of cattle examined with clinically diagnosed lymphosarcoma contained high-titered antibody to 125I-labeled bovine leukemia virus glycoprotein, whereas sera from animals in a disease-free herd were antibody negative.
Effects of mutations in the immunity system of bacteriophage P1
Authors: D'Ari R
Published: January 2020

A mutant of bacteriophage P1 that made an altered c1 repressor is described. The mutant c1 product had two configurations: in lysogens, at high temperatures, it permitted constitutive expression of the normally repressed DNA replication function ban and was insensitive to the action of ant, a product expressed by the virulent mutant P1virs and by the heteroimmune phage P7 (formerly phiamp+) and normally able to overcome c1 repression; in mutant lysogens at low temperatures, the mutant repressor was apparently normal (able to repress ban and sensitive to ant action). Genetic studies of this mutant led to the isolation of a derivative that formed unstable lysogens. These studies suggested that the ban product was normally under c1 control; they further showed that ant overcame c1 repression by inactivating c1 rather than by creating a bypass of repressor activity.
Feline leukemia virus: biochemical and immunological characterization of gag gene-coded structural proteins
Authors: Khan A S , Stephenson J R
Published: January 2020

The major non-glycosylated structural proteins of feline leukemia virus have been isolated, and competition immunoassays have been developed for each. These proteins include the 27,000- to 30,000-molecular-weight major internal antigen designated p30, a 15,000-molecular-weight protein (p15), an acidic protein of 12,000 molecular weight (p12), and a highly basic 10,000-molecular-weight protein (p10). Immunologically and biochemically corresponding proteins of feline and murine leukemia viruses have been identified. and, on the basis of analogy to the known sequence of a prototype type C virus of mouse origin, the map order of the gag region of the feline type C viral genome has been tentatively deduced as NH2-p15-p12-p10-COOH. The demonstration of two feline leukemia virus gag gene-coded proteins, p15 and p12, expressed in the form of an uncleaved precursor in a mink cell line nonproductively transformed by feline sarcoma virus provides indirect support for the proposed sequence.
Bacteriophage T4 Virion Dihydrofolate Reductase: Approaches to Quantitation and Assessment of Function
Authors: Mosher Richard A. , DiRenzo Anthony B. , Mathews Christopher K.
Published: January 2020

This paper is concerned with the physiological role(s) of T4 phage-coded dihydrofolate reductase, which functions both in DNA precursor metabolism and as a virion protein. (i) We have detected enzyme activity in noninfectious particles produced under restrictive conditions by gene 11 mutants. This supports the conclusion of Kozloff et al. (J. Virol.
16
:1401-1408, 1975) that the protein lies in the baseplate, covered by the gene 11 protein. (ii) We have obtained further evidence for virion dihydrofolate reductase as the target for neutralizing activity of T4 dihydrofolate reductase antiserum and as a determinant of the heat lability of the virion. This derives from our observation that the reductases specified by T4B and T4D differ in several properties. (iii) We have investigated several anomalous properties of T4 mutants bearing deletions that reportedly extend into or through the
frd
gene, which codes for dihydrofolate reductase. Evidence is presented that the deletions in fact do not extend through
frd.
These strains direct the synthesis of material that cross-reacts with antiserum to homogeneous dihydrofolate reductase. Moreover, they are all quite sensitive to the phage-neutralizing effects of this antiserum. In addition, they are restricted by several of the hospital strains, wild-type strains of
Escherichia coli
supplied by the California Institute of Technology group. (iv) We have attempted to detect dihydrofolate reductase among early-synthesized proteins present in T4 tails. Two such proteins are seen, one of which is evidently the gene 25 product and one that is a bacterial protein. Quantitation of our electrophoretic technique has allowed determination of the number of molecules of some T4 tail components present per virion. (v) Finally, we have compared the T4 dihydrofolate reductase with the corresponding enzyme specified by two plasmids conferring resistance to trimethoprim (Skold and Widh, J. Biol. Chem.
249
:4324-4325, 1974). Although the enzymes are similar in some properties, they differ in several important respects, including immunological activity.
Extensive in vitro transcription of rous sarcoma virus RNA by avian myeloblastosis virus DNA polymerase and concurrent activation of the associated RNase H
Authors: Darlix J L , Bromley P A , Spahr P F
Published: January 2020

Conditions are described that promote the efficient reverse transcription of most of Rous sarcoma virus (RSV) RNA sequences by avian myeloblastosis virus DNA polymerase in vitro. A detailed analysis of the reverse transcription reaction was carried out using two procedures: in situ analysis of the RNA sequences transcribed and DNA-RNA annealing studies. Under optimal conditions, after 1 h of reaction, practically all RSV RNA sequences were transcribed with a frequency varying from 30 to 90%. The DNA product was at least 95% single stranded, had a chain length ranging from a few hundred up to 5,000 necleotide residues, half of it being larger than 1,000 residues, and, after hybridization at RNA excess, protected the entire RSV genome from RNase digestion, as monitored by the large T1 oligonucleotides of RSV RNA. Analysis of the product of a very short reaction time (5 min) showed that DNA synthesis occurs mainly at three sites, one near the 5' end and two near the center of the subunit RNA. This in in agreement with our previous analysis of a much less efficient reverse transcription reaction. Under optimal conditions of reverse transcription, we find now that the RNase H associated with the avian myeloblastosis virus DNA polymerase is active in degrading the RNA moiety of the RNA-DNA hybrids synthesized.
Dissociation of polyoma virus by the chelation of calcium ions found associated with purified virions
Authors: Brady J N , Winston V D , Consigli R A
Published: January 2020

Analysis of polyoma virions by X-ray fluorometry demonstrated that calcium (Ca2+) was associated with the purified virion. Treatment of purified virions with ethyleneglycol-bis-N,N'-tetraacetic acid (EGTA), which chelates Ca2+, and the reducing agent dithiothreitol caused the virions to dissociate. Electron microscopy revealed that the virions were dissociated to the capsomere level. Incubation of polyoma virions with 150 mM NaCl, 10 mM EGTA, and 3 mM dithiothreitol was optimum for the dissociation reaction. The pH for the dissociation reaction ranged from 7.5 to 10.5. Cesium chloride density gradient centrifugation indicated that both EGTA and dithiothreitol were necessary for dissociation to occur; neither reagent alone dissociated the virus. The major protein product of the dissociated viral particles sedimented at 12S. Relationships between these experiments and the alkaline carbonate-bicarbonate dissociation of polyoma are discussed.
Correlation of virus polypeptide structure with attenuation of poliovirus type 1
Authors: Milstien J B , Walker J R , Eron L J
Published: January 2020

Several avirulent samples of poliovirus type 1 derived in the process attenuating the neurovirulent Mahoney strain show an altered virus capsid polypeptide, VP-1, on polyacrylamide gel electrophoresis of sodium dodecyl sulfate-disrupted virions.
Analysis of polyoma virus DNA replicative intermediates by agarose gel electrophoresis
Authors: Martin R F
Published: January 2020

Agarose gel electrophoresis has been used to fractionate polyoma virus DNA replicative intermediates (RI) according to maturity. Approximate electrophoretic mobility versus maturity relationships were obtained for both intact (supercoiled) and nicked (relaxed) RI. There was considerable overlap between the supercoiled and relaxed RI populations after electrophoretic fractionation. Intact RI could be recovered from preparative agarose gels for further analysis by centrifugation, electron microscopy, re-electrophoresis, or nuclease digestion.
Bacteriophage PMB12 conversion of the sporulation defect in RNA polymerase mutants of Bacillus subtilis
Authors: Bramucci M G , Keggins K M , Lovett P S
Published: January 2020

The pseudotemperate phage PMB12 was isolated from soil on the basis of its ability to enhance the rate of sporulation of Bacillus subtilis 168. PMB12 was subsequently shown to convert the sporulation defect in two genetically distinct classes of sporulation mutants. One class includes those rifampin-resistant mutants that are also spore-negative (mutated at the rif locus). The other class includes a strain carrying the sporulation mutation spoCM-1. The spoCM-1 mutation is linked to cysA15 by PBS1 transduction but is distinct from the rif locus. Several other sporulation mutants were not converted by PMB12. PMB12 is related to phage PBS1. However, PBS1 did not convert the above sporulation mutants. The replication of PBS2, a clear-plaquing derivative of PBS1, is rifampin insensitive, apparently due to a phage-induced rifampin-insensitive RNA polymerase. PMB12 replication is also rifampin insensitive.
Physical map of the bacteriophage T5 genome based on the cleavage products of the restriction endonucleases SalI, SmaI, BamI, and HpaI
Authors: Hamlett N V , Lange-Gufstafson B , Rhoades M
Published: January 2020

A physical map of the bacteriophage T5 genome was constructed by ordering the fragments produced by cleavage of T5 DNA with the restriction endonucleases SalI (4 fragments), SmaI (4 fragments), BamI (5 fragments), and HpaI (28 fragments). The following techniques were used to order the fragments. (i) Digestion of DNA from T5 heat-stable deletion mutants was used to identify fragments located in the deletable region. (ii) Fragments near the ends of the T5 DNA molecule were located by treating T5 DNA with lambda exonuclease before restriction endonuclease cleavage. (iii) Fragments spanning other restriction endonuclease cleavage sites were identified by combined digestion of T5 DNA with two restriction endonucleases. (iv) The general location of some fragments was determined by isolating individual restriction fragments from agarose gels and redigesting the isolated fragments with a second restriction enzyme. (v) Treatment of restriction digests with lambda exonuclease before digestion with a second restriction enzyme was used to identify fragments near, but not spanning, restriction cleavage sites. (vi) Exonucleases III treatment of T5 DNA before restriction endonuclease cleavage was used to locate fragments spanning or near the natural T5 single-chain interruptions. (vii) Analysis of the products of incomplete restriction endonuclease cleavage was used to identify adjacent fragments.
Ultrastructural studies of H-1 parvovirus replication. IV. Crystal development and structure with the temperature-sensitive mutant ts1
Authors: Singer I I , Rhode S L
Published: January 2020

Electron microscopy was used to study the development and structure of viral crystals of ts1, a temperature-sensitive mutant of H-1 parvovirus. At early times postinfection, at the restrictive temperature, empty H-1 capsids aggregated to form conspicuous noncrystalline conglomerates in human NB cell nuclei; these particles did not associate with euchromatin as in wild-type H-1 infections. Later on, the capsid aggregated appeared to form polycrystals exhibiting rod-like, hexagonal, and cubic patterns that were interconvertible using a goniometer specimen stage. The unit cell of this crystal was cubic, consisted of 16 empty particles, and measured 50 nm on each side. Full particles made at the permissive temperature were never observed under restrictive conditions. Experiments in which cultures were shifted form the permissive to the restrictive temperature showed that full virions were not incorporated into crystals. The crystals dissociated into individual particles when changes were made from restrictive to permissive conditions. Correlations between the formation of crystals at the restrictive temperature, their dissociation into capsid components after shifting from the restrictive to the permissive state, and the extent of host cell damage were also observed. Possible roles of cellular functions in regulating ts1 H-1 polycrystal assembly and dissociation are discussed.
Evidence of a repetitive sequence in vaccinia virus DNA
Authors: Pedrali-Noy G , Weissbach A
Published: January 2020

Analysis of vaccinia DNA by reassociation kinetics revealed that 7% of the genome contains a sequence repeated 10 times. This sequence does not contain any host cell DNA, is viral specific, and is found in virions passed at either high or low multiplicities of infection.
Adenovirus type 12 DNA sequences in primary hamster tumors
Authors: Lee K C , Mak S
Published: January 2020

In five out of six primary hamster tumors induced by adenovirus type 12, less than 55% of the adenovirus type 12 genome is present. Various fragments of the integrated viral DNA were present in non-equimolar amounts.
Isolation of the viral DNA replication complex from adeno-associated virus type 1-infected cells
Authors: Handa H , Shimojo H
Published: January 2020

The replication complex active in adeno-associated virus type 1 (AAV-1) DNA synthesis in vitro was solubilized, with a nonionic detergent, from the nuclei of human embryonic kidney cells coinfected with AAV-1 and an early temperative-sensitive mutant (ts125) of human adenovirus type 5 at the nonpermissive temperature (40.5 degrees C). The complex sedimented with a mean size of 23S and contained parental AAV-1 DNA. Most of the DNA synthesized with the AAV-1 DNA replication complex in vitro was AAV-1 DNA, as revealed by DNA-DNA hybridization and sedimentation in a neutral sucrose gradient. However, it sedimented in an alkaline sucrose gradient as molecules smaller than AAV-1 DNA (14.4S). The AAV-1 DNA replication complex was not formed in cells infected with AAV-1 alone.
Characterization of Gazdar murine sarcoma virus by nucleic acid hybridization and analysis of viral expression in cells
Authors: Pang R H , Phillips L A , Haapala D K
Published: January 2020

Gazdar murine sarcoma virus (Gz-MSV) and Moloney murine sarcoma virus (M-MSV) are closely related. The complete M-MSV-specific nucleic acid sequences constituted a major portion of Gz-MSV-specific sequences. The MSV-specific sequences in both Gz-MSV and M-MSV genomes shared homology with hamster leukemia virus nucleic acid sequences. Both rat cells (S+L+) and hamster (S+L-) cells expressed two viral proteins of 68,000 and 70,000 daltons. These proteins were immunologically related to p60 purified from m1 virions of M-MSV.
In vivo functional interaction between DNA polymerase and dCMP-hydroxymethylase of bacteriophage T4
Authors: Chao J , Leach M , Karam J
Published: January 2020

Some mutations in the structural gene for T4 DNA polymerase (gene 43) behave as suppressors of a deficiency in T4 dCMP-hydroxymethylase (gene 42). The suppression appears to involve a functional interaction between the two enzymes at the level of DNA replication. The hydroxymethylase deficiency caused DNA structural abnormalities in replication, and DNA polymerase lesions appeared to partially reverse these abnormalities. The results do not necessarily imply protein-protein interactions between the two enzymes, although both enzymes appear to play roles in controlling the fidelity of phage DNA replication.
Evidence for two nucleotide sequence orientations within the terminal repetition of adeno-associated virus DNA
Authors: Spear I S , Fife K H , Hauswirth W W , Jones C J , Berns K I
Published: January 2020

Duplex adeno-associated virus (AAV) DNA, produced by annealing plus and minus virion single strands, has been digested with several bacterial restriction endonucleases. These studies reveal the existence of alternate secondary structures at the termini of duplex AAV DNA. Analysis of the sites of endo R-Hpa II cleavage, the products of complete endo R-Hpa II digestion, and the multiple terminal secondary structures leads to the conclusion that there are two possible nucleotide sequences at each end of AAV DNA. A model that attributes the terminal nucleotide sequence heterogeneity to two possible orientations of the first 120 nucleotides at each end of the DNA is proposed; in one case the sequence is 1 to 120; in the other case the sequence is inverted. An origin of the inversion is suggested based on previously described intermediates in AAV DNA replication.
In vitro transcription of the avian retrovirus genome by the alpha form of the viral RNA-directed DNA polymerase
Authors: Collett M S , Grandgenett D P , Faras A J
Published: January 2020

The nature of transcription of the avian retrovirus RNA genome by the alpha form of the viral RNA-directed DNA polymerase has been investigated. Transcription was most efficient when Mn2+ was provided as the divalent metal ion. The patterns of DNA transcription using 70S RNA, 35S RNA-tRNAtrp, or 35S RNA-oligo(dT)12-18 template-primer complexes by the alpha DNA polymerase were essentially identical to those obtained using the alphabeta form. The alpha DNA polymerase appears to be deficient in the synthesis of true duplex DNA but is able to synthesize hairpin-structured DNA initiated at the 5' terminus of the viral genome on the tRNAtrp primer molecule.
Properties of influenza C virus grown in cell culture
Authors: O'Callaghan R J , Loughlin M , Labat D D , Howe C
Published: January 2020

Influenza C virus was propagated successfully in primary chicken embryo lung (CEL) and fibroblast cells and in Madin-Darby canine kidney (MDCK) cells. In other cell lines, either no virus or only noninfectious hemagglutinin (HA) was produced. In productively infected cells (CEL), HA and infectious virus appeared by 24 h and reached a maximum by 36 to 48 h, cell-associated virus remaining at a constant low level. Infected Vero cells produced noninfective HA by 24 h which also remained predominantly cell associated until 60 to 72 h, when the cells disintegrated. Viral antigen was demonstrable on membranes of both CEL- and Vero-infected cells at 24 h; Vero cells yielded membrane vesicles containing HA, but none of the spherical or filamentous viral particles synthesized in CEL cells. Influenza C virus produced in cell culture or in eggs differed in several important respects from A and B viruses and from Newcastle diseases virus. All influenza C preparations, regardless of infectivity or source, lacked detectable neuraminidase activity, yet retained the ability specifically to inactivate receptors only for influenza C. Influenza C HA was not inhibited by soluble glycoproteins highly active against HA of A virus. A rat serum glycoprotein uniquely inhibited influenza C by binding to the surface components of virious.