bluuebunny/crossref_metadata_2025 huggingface dataset:
Herpes-Type Virus of the Frog Renal Adenocarcinoma
Authors: Stackpole Christopher W.
Published: January 2020

Development of the herpes-type virus of the frog kidney tumor was investigated by electron microscopy and high-resolution autoradiography in eyechamber transplants of tumor maintained at 7.5 C for up to 27 weeks. Virus particles were first detected at 10 weeks in nuclei containing aggregates of dense granular material. The initial incorporation of a pulse of
3
H-thymidine into these aggregates indicated that they contained newly synthesized viral deoxyribonucleic acid. Capsids enclosing doubleshelled cores were labeled with
3
H-thymidine before capsids with dense cores, and intermediate core forms were observed, suggesting that the double-shelled core transforms into the dense core. Particles with dense cores were observed while being enveloped by budding through the inner membrane of the nuclear envelope, and subsequently while being unenveloped in passing through the outer membrane into the cytoplasm. Virus particles within the cytoplasm acquired fibrillar coats and budded into vesicles, from which they were released, in enveloped form, at the cell surface. Tubular forms and particles considerably smaller than virus particles were regularly encountered in infected nuclei, and the relationship of these forms to virus replication is discussed.
Deoxyribonucleic Acid of Adeno-associated Satellite Virus
Authors: Mayor Heather D. , Jordan Liane , Ito Michio
Published: January 2020

Staining patterns suggest that in the adeno-associated satellite virion there exist quasi single-stranded regions which are renatured after extraction to exhibit double strandedness.
Dependence of Vegetative Recombination Among
Haemophilus influenzae
Bacteriophage on the Host Cell
Authors: Boling Maxon E. , Setlow Jane K.
Published: January 2020

Vegetative recombination of temperature-sensitive mutants of
Haemophilus influenzae
phage HP1
c
l was measured in wild-type
H. influenzae
strain Rd and in strain DB117, an ultraviolet-sensitive, transformation-defective mutant of the Rd strain. Recombinants are formed with low frequency in wild-type cells, but no recombination was detectable in DB117. It is concluded that these phage make use of the host cell enzymes for vegetative recombination. Lysogenization readily takes place in both strains.
Persistent Infection of a Rat Nephroma Cell Line with Kilham Rat Virus
Authors: Wozniak Jeanette , Hetrick Frank
Published: January 2020

A rat nephroma cell line was found to be a carrier culture of the Kilham rat virus. Infectious virus was demonstrable only by passage of culture materials into other host systems.
Temperature-Sensitive Behavior of the Hemagglutinin in a Temperature-Sensitive Mutant Virion of Sindbis
Authors: Yin Fay Hoh
Published: January 2020

The hemagglutinating ability of a temperature-sensitive mutant virion was reversibly lost when the temperature of hemagglutination was increased from 27 to 37 C.
Properties of Simian Virus 40 Rescued from Cell Lines Transformed by Ultraviolet-Irradiated Simian Virus 40
Authors: Kit Saul , Kurimura T. , Dubbs D. R.
Published: January 2020

Simian virus 40 (SV40) strains have been rescued from various clonal lines of mouse kidney cells that had been transformed by ultraviolet (UV)-irradiated SV40. To learn whether some of the rescued SV40 strains were mutants, monkey kidney (CV-1) cells were infected with the rescued virus strains at 37 C and at 41 C. The SV40 strains studied included strains rescued from transformed cell lines classified as “good,” “average,” “poor,” and “rare” yielders on the basis of total virus yield, frequency of induction, and incidence of successful rescue trials. Four small plaque mutants isolated from “poor” yielder lines and fuzzy and small plaque strains isolated from an “average” and a “good” yielder line, respectively, were among the SV40 strains tested. Virus strains rescued from all classes of transformed cells were capable of inducing the transplantation antigen, and they induced the intranuclear SV40-T-antigen, thymidine kinase, deoxyribonucleic acid (DNA) polymerase, and cellular DNA synthesis at 37 C and at 41 C. With the exception of four small plaque strains rescued from “poor” yielders, the rescued SV40 strains replicated their DNA and formed infectious virus with kinetics similar to parental SV40 at either 37 or 41 C. The four exceptional strains did replicate at 37 C, but replication was very poor at 41 C. Thus, only a few of the rescued virus strains exhibited defective SV40 functions in CV-1 cells. All of the virus strains rescued from the “rare” yielder lines were similar to parental SV40. Several hypotheses consistent with the properties of the rescued virus strains are discussed, which may account for the significant variations in virus yield and frequency of induction of the transformed cell lines.
In Vitro Transformation by the Adenovirus-Simian Virus 40 Hybrid Viruses
Authors: Levin Myron J. , Black Paul H. , Coghill Susan L. , Dixon Cynthia B. , Henry Patrick H.
Published: January 2020

The ribonucleic acid-deoxyribonucleic acid hybridization technique was utilized to determine the presence of adenovirus (ad) and SV40 genetic information and to determine which ad genomes were present in clones of hamster cells transformed with the ad 2-SV40 and ad 12-SV40 transcapsidant hybrid virus populations. The results were correlated with the morphology of the transformed cells and colonies. It was found that cells transformed by either transcapsidant virus which had an SV40 morphology contained the ad 7 and SV40 genomes, whereas cells with a typical ad morphology contained only ad genetic information. Cells and colonies with morphological features of both ad- and SV40-transformed cells contained either the ad 2, or ad 12 genomes, depending on the transcapsidant used, together with the ad 7 and SV40 genomes. The results indicate the following: at least three different events occurred during transformation of hamster cells by the transcapsidant virus populations; the morphology of the resulting clones is determined by the viral genome(s) present; the linkage of the ad 7-SV40 genomes is confirmed since the ad 7- SV40 genomes were never found to be dissociated; the defective ad 7-SV40 genomes are capable of causing transformation; and the transcapsidant particle is probably composed of only ad 7 and SV40 genetic information.
Morphogenesis of Newcastle Disease Virus in Chorioallantoic Membrane
Authors: Feller Ursula , Dougherty Robert M. , Di Stefano Henry S.
Published: January 2020

Chick embryo chorioallantoic membrane, infected with the Blacksburg strain of Newcastle disease virus, was examined with an electron microscope to investigate the sequence of viral-induced host cell alterations. These were evident mostly in the endodermal epithelial cells lining the allantoic sac and were divided arbitrarily into three stages. Stage 1 was characterized by commencement of cell hypertrophy and hyperplasia and presence of fewer cytoplasmic inclusion bodies normally found in the cells; in stage 2, juxtanuclear nucleocapsid-glycogen aggregates appeared, and there were increased numbers of microvilli; stage 3 was characterized by increased cytoplasmic density and evidence of viral assembly and release. The morphological features of viral assembly and the virion are also described.
Morphogenesis of Influenza A Virus in Ehrlich Ascites Tumor Cells as Revealed by Thin-Sectioning and Freeze-Etching
Authors: Bächi T. , Gerhard W. , Lindenmann J. , Mühlethaler K.
Published: January 2020

The budding of a tumor-adapted strain of influenza A
0
virus at the surface of Ehrlich ascites tumor cells was studied by electron microscopy. Thin sections of budding sites showed the formation of a fuzzy coat on the outside of the cell membrane and simultaneously the apposition of a dark layer on the inner side. The continuity of cellular and viral membrane seemed to be preserved up to the point where the virion remained attached by only a thin stalk. Freeze-etching of virus budding sites yielded pictures in which a clear differentiation between the viral membrane and the host cell membrane was visible. The breaks across the fuzzy coat revealed striations corresponding to the “spikes” seen in negative contrast, whereas tangentially broken virus particles were best interpreted by assuming that splitting occurred midway between the two outer layers of the envelope.
Structure and Development of Viruses as Observed in the Electron Microscope
Authors: Morgan Councilman , Rosenkranz Herbert S. , Mednis Baiba
Published: January 2020

Stages in the direct penetration of adenovirus through the cell membrane are illustrated. Phagocytosis with rupture of the vacuole and release of virus into the cytoplasm may also account for entry of some particles. Uncoating by digestion within phagosomes was not observed. Rather, alteration of capsid and core occurred to virions free in the cytoplasm. Nucleoprotein released from virus close to the nucleus was transported to the nuclear matrix by a unique mechanism. These events were not prevented by puromycin and hence were not dependent upon the synthesis of new enzymes. They were, however, energy-dependent.
Ribonucleic Acid and Protein Synthesis in Chick Embryo Cells Infected with Fowl Plague Virus
Authors: Joss A. , Gandhi S. S. , Hay A. J. , Burke D. C.
Published: January 2020

Fowl plague virus comprised four major protein components and several minor ones, two strains of the virus giving similar results. One of the components was identified as the nucleocapsid protein. Synthesis of the virion proteins could readily be detected in infected cells 3 hr after infection. The two subcellular fractions associated with viral ribonucleic acid (RNA) polymerase activity (nuclei and ribosomal pellet) were associated with the protein of the nucleocapsid and a second virion protein of unidentified function. Measurement of viral RNA and protein synthesis in cells infected with preparations of ultraviolet irradiated virus showed that the capacity to synthesise the RNA and protein species of highest molecular weight was lost most quickly, suggesting that the pieces of viral RNA function independently.
Characterization of Deoxyribonucleases Induced by Poxviruses
Authors: Jungwirth C. , Launer J. , Dombrowski G. , Horák I.
Published: January 2020

Increases in deoxyribonuclease activity assayed at alkaline
p
H can be observed in poxvirus-infected cells when native or denatured deoxyribonucleic acid (DNA) is used as substrate. The deoxyribonuclease assayable with native DNA as substrate, induced in HeLa cells by cowpoxvirus or vaccinia virus WR, can be separated from the corresponding enzyme present in normal cells by chromatography on diethylaminoethyl cellulose. In addition, the two enzymes induced in the virus-infected cells differ from each other in their chromatographic properties. The two induced enzymes have been further characterized with respect to properties of enzymatic reaction.
Two virus-specific rna species are present in cells transformed by defective leukemia virus OK10
Authors: Chiswell D J , Ramsay G , Hayman M J
Published: January 2020

OK10 is a defective leukemia virus which shares some biological and biochemical properties of avian myelocytomatosis virus (MC29). We investigated the pattern of transcription of OK10 in both quail and chicken cells. In both cell types, OK10 produced two polyadenylated RNA species of 8.6 and 3.5 kilobases, which both contained sequences derived from the 5' end of the genome and also the presumed transforming gene (myc). This is a novel form of expression for defective leukemia viruses of the MC29 subgroup and may indicate that there is an as-yet-unidentified protein produced in OK10-infected cells which may be involved in transformation.
Deletion of a 9,000-base-pair segment of the vaccinia virus genome that encodes nonessential polypeptides
Authors: Moss B , Winters E , Cooper J A
Published: January 2020

Deletions contained within the genomes of unstable and stable variants of vaccinia virus (strain WR) were analyzed. Restriction endonuclease mapping and hybridization to specific 32P-labeled DNA probes indicated that more than 6 X 10(6) daltons of DNA were deleted from the variants. In each case, the deletion occurred on the left side of the genome and started very close to the junction of the inverted terminal repetition and unique sequence. Both variants also contained a new SstI side on the right side of the genome. Hybridization selection and cell-free translation experiments indicated that these variants lost the ability to synthesize at least eight early mRNA's mapping within the deleted region. Although the deleted DNA was not essential for replication of the WR strain of vaccinia virus under laboratory conditions of infection, it presumably has a defined role under other circumstances. This conclusion was based on the conservation within the Elstree strain of vaccinia, the Utrecht strain of rabbitpox, and the Brighton strain of cowpox virus of sequences homologous to the deleted DNA. Moreover, mRNA's that hybridized to the deleted vaccinia virus DNA segment and encoded similar size polypeptides were made in cells infected with rabbitpox and cowpox viruses.
phi X174-directed DNA and protein syntheses in infected minicells
Authors: Reeve J N
Published: January 2020

Phi X174-infected minicells, produced by Escherichia coli PC2251, synthesized 11 phi X174-encoded polypeptides. The infecting single-stranded viral genome was converted to a double-stranded, closed circular, replicative form (replicative form I). Little, if any, replicative form I replication took place, and synthesis of progeny single-stranded molecules could not be detected.
Comparisons of rotavirus polypeptides by limited proteolysis: close similarity of certain polypeptides of different strains
Authors: Dyall-Smith M L , Holmes I H
Published: January 2020

The polypeptides of SA11 rotavirus produced in virus-infected cells were analyzed by limited proteolysis, using Staphylococcus aureus V8 protease. This clearly distinguished between all the known primary gene products of the virus and allowed relationships between other infected-cell proteins, and between infected-cell and virus structural proteins, to be ascertained. A comparison of the proteolysis cleavage patterns between SA11 rotavirus and the human rotavirus Wa was also performed which demonstrated a marked conservation in the digestion patterns among nonstructural and inner-shell structural proteins, but a marked variation in the digestion patterns among outer-shell structural proteins.
Ultraviolet irradiation inhibits encapsidation of simian virus 40 chromatin
Authors: Roman A , Edenberg H J
Published: January 2020

During normal maturation and majority of pulse-labeled simian virus 40 DNA progresses from chromatin to previrions and virions within 5 h. UV light inhibits this progression. In heavily irradiated cultures (108 J m-2) most of the simian virus 40 DNA synthesized immediately before irradiation remains as chromatin for at least 5 h. This inhibition of maturation seems to be a result of the inhibition of protein synthesis. The data suggest that the pool of proteins required for maturation is sufficient to convert one-third of the simian virus 40 DNA molecules labeled in a 10-min pulse (at 33 h postinfection) from chromatin to previrions and virions and is exhausted within 1 h.
Sequence analysis of cDNA's derived from the RNA of Sindbis virions and of defective interfering particles
Authors: Monroe S S , Ou J H , Rice C M , Schlesinger S , Strauss E G , Strauss J H
Published: January 2020

Sindbis virus generates defective interfering (DI) particles during serial high-multiplicity passage in cultured cells. These DI particles inhibit the replication of infectious virus and can be an important factor in the establishment and maintenance of persistent infection in BHK cells. In an effort to understand how these DI particles are generated and how they interfere with the replication of standard virus, we performed a partial sequence analysis of the RNA obtained from two independently isolated populations of DI particles and from two Sindbis virus variants and compared these with the RNA of the parental wild-type virus. The 3'-terminal regions of the RNAs were sequenced by the dideoxy chain terminating method. Internal regions of the RNA were examined by restriction endonuclease digestion of cDNA's made to the various RNAs and by direct chemical sequencing of 5' end-labeled restriction fragments from cDNA made to the DI RNAs. One of the variant viruses examined was originally derived from cells persistently infected with Sindbis virus for 16 months and is resistant to interference by the DI strains used. In the 3'-terminal region of the RNA from this variant, only two base changes were found; one of these occurs in the 20-nucleotide 3'-terminal sequence which is highly conserved among alphaviruses. The DI RNA sequences were found to have been produced not by a single deletional event, but by multiple deletion steps combined with sequence rearrangements; all sequences examined are derived from the plus strand of Sindbis virion RNA. Both DI RNAs had at least 50 nucleotides of wild-type sequence conserved at the 3' terminus; in addition, they both contained conserved and perhaps amplified sequences derived from the non-26S region of the genome which may be of importance in their replication and interference ability.
In vitro and in vivo inhibition of primary transcription of vesicular stomatitis virus by a defective interfering particle
Authors: Bay P H , Reichmann M E
Published: January 2020

A unique defective interfering (DI) particle, generated by a heat-resistant (HR) mutant of Indiana serotype vesicular stomatitis virus, was capable of inhibiting primary transcription by heterologous New Jersey serotype virions. The correlation between this phenomenon and the lowering of viral yields from doubly infected cells was investigated by the construction of chimeric DI particles containing the HR DI particle genome with a thermolabile polymerase. At the nonpermissive temperature, these DI particles were unable to self-transcribe, inhibit virion primary transcription, or reduce virion yield, but were able to be replicated. These results suggested that self-transcription of the HR DI particle genome was a prerequisite for heterotypic interference, but not for its own replication. Inhibition of virion primary transcription by HR DI ribonucleocapsids was also observed in vitro. At low HR DI to virion ribonucleocapsid ratios, the extent of inhibition was concentration dependent, whereas at high ratios, the amount of inhibition was concentration independent, approaching a limiting maximum value. A speculative mathematical model, which quantitatively accounts for these data, is presented. According to this model, the higher affinity for polymerase molecules by the HR DI ribonucleocapsids is explained in terms of dissociation events during transcription, which are more frequent in the longer virion ribonucleocapsids.
Cloning and characterization of an envelope-specific probe from xenotropic murine leukemia proviral DNA
Authors: Buckler C E , Hoggan M D , Chan H W , Sears J F , Khan A S , Moore J L , Hartley J W , Rowe W P , Martin M A
Published: January 2020

An 8.9-kilobase EcoRI restriction fragment was cloned from mink cells chronically infected with NFS-Th-1 xenotropic murine leukemia virus by using a lambda phage host vector system. After its transfer into pBR322, the EcoRI DNA insert was characterized and found to contain 6.7 kilobases of proviral DNA sequences and 2.2 kilobases of mink cellular DNA flanking the 5' end of the viral genome. A 500-base pair fragment which was located at the 3' terminus of the cloned DNA insert and which mapped to the env region of xenotropic proviral DNA was subcloned into pBR322. This xenotropic envelope proviral DNA segment did not hybridize to ecotropic murine leukemia proviruses but did anneal to representative alpha and beta xenotropic and seven different mink cell focus-inducing proviral DNAs. The cloned xenotropic envelope-specific probe was also used in blot hybridization experiments to analyze the arrangement of related sequences in preparations of different mouse liver DNAs.
Initiation of adenovirus DNA replication: detection of covalent complexes between nucleotide and the 80-kilodalton terminal protein
Authors: Challberg M D , Ostrove J M , Kelly T J
Published: January 2020

We have previously shown that the 5'-terminal deoxycytidine residue of each nascent adenovirus 5 DNA strand synthesized in vitro is covalently linked to the 80-kilodalton (kd) terminal protein precursor via a phosphodiester bond to a serine residue in the protein. When extracts prepared from adenovirus 5-infected cells are incubated with [alpha-33P]dCTP as the only added deoxynucleoside triphosphate, complexes consisting of nucleotide covalently linked to the 80-kd protein can be detected. The nucleotide moieties present in such complexes include d(pC) and d(pCpA), the 5'-terminal nucleotide and dinucleotide of adenovirus 5 DNA, respectively, as well as some longer oligonucleotides. The formation of these complexes requires the presence of adenovirus DNA containing the attached 55-kd terminal protein and ATP. Extracts from H5ts125-infected cells which are defective in DNA replication catalyze complex formation to the same extent as extracts prepared from wild-type infected cells; thus, the presence of the adenovirus-coded 72-kd DNA-binding protein is apparently not required. Most, if not all, of the 80-kd protein-nucleotide complexes that are formed are noncovalently bound to the input viral DNA. These observations are consistent with the protein-priming model for the initiation of adenovirus DNA replication.
Two large virion envelope glycoproteins mediate Epstein-Barr virus binding to receptor-positive cells
Authors: Wells A , Koide N , Klein G
Published: January 2020

The four major Epstein-Barr virion envelope components were separated by column chromatography and reconstituted into artificial liposomes. These liposomes were tested for their ability to bind selectively to Epstein-Barr virus receptor-positive cells. Only when the two high-molecular-weight glycoproteins, VE1 and VE2, were present together was a stable binding complex formed. The addition of the other virion envelope components did not increase the levels of binding. This binding was inhibited by unlabeled viable virions and by neutralizing antisera, which recognized the two components. Adsorption of viable virus was also eliminated by the antisera. The enzyme susceptibility pattern of the cell-liposome interaction is similar to that of the virus-cell interaction, thus confirming the specificity of the binding site. A model for Epstein-Barr virus binding in which VE1 and VE2 coordinately recognize the same binding site is presented.
Inhibition of poliovirus polymerase by guanidine in vitro
Authors: Tershak D R
Published: January 2020

Extracts from poliovirus-infected HeLa cells synthesized 35s viral RNA, replicative intermediate, and double-stranded RNA in vitro. Guanidine inhibited the synthesis of all three species of RNA; production of 35s RNA was most sensitive to the inhibitor. Pulse-chase experiments with [3H]UTP indicated that guanidine had no detectable effect on elongation of polynucleotide chains or the release of completed RNA chains from the viral replication complex. Experiments in which short pulses of precursor were used suggest that guanidine blocked the initiation step of RNA synthesis in vitro.
Multimeric forms of herpes simplex virus type 2 glycoproteins
Authors: Eberle R , Courtney R J
Published: January 2020

Herpes simplex virus type 2-specific glycoproteins present in detergent extracts of infected cells were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under conditions designed to permit detection of multimeric forms of these glycoproteins. Two high-molecular-weight glycosylated species were detected when samples were disrupted at lower temperatures or in the absence of any reducing agents. One multimer having an apparent molecular weight of 275,000 was identified as a multimer of the gA or gB glycoprotein or both. The second glycoprotein, having a molecular weight of approximately 230,000, was identified as a multimeric form of the gC glycoprotein. These data indicate that the gC as well as the gA and gB glycoproteins of herpes simplex virus type 2 may exist in a multimeric form.
Occurrence of temperature-sensitive influenza A viruses in nature
Authors: Chu C M , Tian S F , Ren G F , Zhang Y M , Zhang L X , Liu G Q
Published: January 2020

The origin and characteristics of the first naturally occurring temperature-sensitive (ts) strain of influenza A virus identified in 1973, Xia-ts, are described. Natural ts strains were found to occur in the early egg passage material of all influenza A subtypes examined, but the proportion of ts virus varied from 8.3% for old H1N1 virus (1949 to 1957) to 82.4% for recent H3N2 virus (1979 to 1980). A number of strains were found to be composed of a mixture of ts and wild-type (ts+) particles. Six natural ts strains with different shutoff temperatures and one ts+ strain of the H1N1 subtype were tested in antibody-free volunteers. Strains with a shutoff temperature of 38 degrees C or lower caused very mild symptoms, whereas those with a shutoff temperature of 39 degrees C and the ts+ strain were much more reactogenic. By complementation tests against a set of prototype WSN ts mutants with a defined genetic lesion, the ts lesion of two H3N2 viruses (HK/8/68 and Xia-ts) was located on the NP gene and that of two H1N1 viruses (Tianjin/78/77 and Beijing/1/79) was located on the M protein gene. The present study demonstrates the widespread occurrence in nature of influenza viruses of different degrees of temperature sensitivity and presumably of different degrees of virulence.
Characterization of proviruses cloned from mink cell focus-forming virus-infected cellular DNA
Authors: Khan A S , Repaske R , Garon C F , Chan H W , Rowe W P , Martin M A
Published: January 2020

Two proviruses were cloned from EcoRI-digested DNA extracted from mink cells chronically infected with AKR mink cell focus-forming (MCF) 247 murine leukemia virus (MuLV), using a lambda phage host vector system. One cloned MuLV DNA fragment (designated MCF 1) contained sequences extending 6.8 kilobases from an EcoRI restriction site in the 5' long terminal repeat (LTR) to an EcoRI site located in the envelope (env) region and was indistinguishable by restriction endonuclease mapping for 5.1 kilobases (except for the EcoRI site in the LTR) from the 5' end of AKR ecotropic proviral DNA. The DNA segment extending from 5.1 to 6.8 kilobases contained several restriction sites that were not present in the AKR ecotropic provirus. A 0.5-kilobase DNA segment located at the 3' end of MCF 1 DNA contained sequences which hybridized to a xenotropic env-specific DNA probe but not to labeled ecotropic env-specific DNA. This dual character of MCF 1 proviral DNA was also confirmed by analyzing heteroduplex molecules by electron microscopy. The second cloned proviral DNA (designated MCF 2) was a 6.9-kilobase EcoRI DNA fragment which contained LTR sequences at each end and a 2.0-kilobase deletion encompassing most of the env region. The MCF 2 proviral DNA proved to be a useful reagent for detecting LTRs electron microscopically due to the presence of nonoverlapping, terminally located LTR sequences which effected its circularization with DNAs containing homologous LTR sequences. Nucleotide sequence analysis demonstrated the presence of a 104-base-pair direct repeat in the LTR of MCF 2 DNA. In contrast, only a single copy of the reiterated component of the direct repeat was present in MCF 1 DNA.
Further characterization of mRNA's of mouse hepatitis virus: presence of common 5'-end nucleotides
Authors: Lai M M , Patton C D , Stohlman S A
Published: January 2020

The mouse hepatitis virus strain A59 codes for seven RNA species in the infected cells. These virus-specific RNAs were found to be polysome associated and therefore likely to represent mRNA's. All of them have common 3'-end sequences (Lai et al., J. Virol. 39:823-834, 1981). Their structure was further studied with respect to their 5'-end sequences. It was found that all of these mRNA's contained cap structures at their 5' ends. Furthermore, the cap-containing oligonucleotides which represent the sequences immediately adjacent to the 5' ends were found to be the same for most, if not all, of the seven virus-specific mRNA's. These sequences are also identical to the 5'-end sequences of the virion RNA genome. The 5'-end sequences were tentatively determined to be 5'-cap-N-UAAG. The presence of the common nucleotides in all of the virus-specific RNAs in mouse hepatitis virus strain A59 suggests several possible mechanisms of synthesis for these RNAs. The significance of these findings is discussed.
Guanidine-resistant defective interfering particles of poliovirus
Authors: Tershak D R
Published: January 2020

A mixture containing standard poliovirus and D3 particles (mutants with deletions in the capsid locus) was serially passaged in the presence of guanidine. Within five growth cycles, the standard virus was guanidine resistant, but the D3 particles were guanidine sensitive, even after 21 passages with the inhibitor. By passage 40 with guanidine, D3 particles were eliminated, and a new deletion mutant (DX) appeared in the virus population. D3 particles contained a 15% deletion, and DX particles contained a 6% deletion in the capsid locus. Although neither mutant induced the synthesis of NCVP1a or a complete complement of capsid proteins after infection, cells infected with DX particles produced two novel proteins, which had molecular weights of approximately 68,000 and 25,000.
Viral gene products in adenovirus type-2 transformed hamster cells
Authors: Esche H
Published: January 2020

I have analyzed viral gene products expressed in five adenovirus type 2 (Ad2)- cytoplasmic, viral RNA which was selected by hybridization to cloned restriction endonuclease fragments of Ad2 DNA. Proteins synthesized in vitro were analyzed by electrophoresis in sodium dodecyl sulfate-polyacrylamide gels and compared with those directed by RNAs prepared from productively infected cells. The early regions E1 and E4 of adenovirus type 2 (Ad2) were found to be expressed in all of five Ad2-transformed hamster embryo cells lines. RNA transcribed from early region E2, which codes for the 72,000-molecular-weight (72K) DNA-binding protein was detected in cell line HE1 only, and early region E3 was expressed exclusively in cell line HE4. RNA transcribed from the region between approximately 12 and 35 map units, coding for immediate early (13.5K, 52/53K) and immediate early proteins (13.6K, 16K, 17K, 87K), as well as RNA from late genes, was not found in any of the cell lines HE1 to HE5 had electrophoretic mobilities similar to those programmed by RNA from productively infected cells.
Orientation of the Genome of
Autographa californica
Nuclear Polyhedrosis Virus: a Proposal
Authors: Vlak Just M. , Smith Gale E.
Published: January 2020

The nuclear polyhedrosis virus of the alfalfa looper
Autographa californica
contains a double-stranded, circular DNA genome. Fourteen scientists agreed to accept an orientation of this circular genome with respect to a physical map of the restriction endonuclease cleavage sites.
UV irradiation analysis of complementation between, and replication of, RNA-negative temperature-sensitive mutants of Newcastle disease virus
Authors: Peeples M E , Bratt M A
Published: January 2020

Random UV irradiation-induced lesions destroy the infectivity of Newcastle disease virus (NDV) by blocking downstream transcription from the single viral promoter. The nucleocapsid-associated polypeptides most likely to be involved in RNA synthesis are located at the extreme ends of the genome: NP and P are promoter proximal genes, and L is the most distal gene. We attempted to order the two temperature-sensitive (ts) RNA-negative (RNA-) mutant groups of NDV by determining the UV target sizes for the complementing abilities of mutants A1 and E1. After UV irradiation, E1 was unable to complement A1, a result compatible with the A mutation lying in the L gene. In contrast, after UV irradiation, A1 was able to complement E1 for both virus production and viral protein synthesis, with a target size most consistent with the E mutation lying in the P gene. UV-irradiated virus was unable to replicate as indicated by its absence in the yields of multiply infected cells, either as infectious virus or as particles with complementing activity. After irradiation, ts mutant B1 delta P, with a non-ts mutation affecting the electrophoretic mobility of the P protein, complemented E1 in a manner similar to A1, but it did not amplify the expression of delta P in infected cells. This too is consistent with irradiated virus being unable to replicate despite the presence of the components needed for replication of E1. At high UV doses, A1 was able to complement E1 in a different, UV-resistant manner, probably by direct donation of input polypeptides. Multiplicity reactivation has previously been observed at high-multiplicity infection by UV-irradiation paramyxoviruses. In this case, virions which are noninfectious because they lack a protein component may be activated by a protein from irradiation virions.
RNA-dependent RNA polymerase activity in coronavirus- infected cells
Authors: Dennis D E , Brian D A
Published: January 2020

An enzymatic activity which incorporates [3H]UMP into acid-precipitable material in the presence of endogenous template was found in the cytoplasm of porcine cells infected with the transmissible gastroenteritis virus of swine. This activity was not found in uninfected control cells, nor was it found in purified virus. The activity was associated with the mitochondrial fraction of infected cells, suggesting that the enzyme is membrane bound. The activity required the presence of all three ribonucleoside triphosphates in addition to [3H]UTP, and it was not inhibited by actinomycin D. The heated product was digested by RNase but not by DNase. Mg2+ was required for enzymatic activity, and its optimal concentration was approximately 5 mM. The size of the in vitro products was compared by electrophoresis with that of in vivo-synthesized virus-specified RNA to confirm the viral specificity of the polymerase activity. Virus-specified RNA from infected cells consisted of 10 species of single-stranded, polyadenylated RNA with molecular weights of 6.8 X 10(6), 6.2 X 10(6), 3.15 X 10(6), 1.40 X 10(6), 1.05 X 10(6), 0.94 X 10(6), 0.66 X 10(6), 0.39 X 10(6), 0.34 X 10(6), and 0.24 X 10(6). In vitro synthesized RNA consisted of a high-molecular-weight species, of apparently higher molecular weight than genomic RNA, and two single-stranded species that electrophoretically comigrated with the species of 1.40 X 10(6) and 0.66 X 10(6) molecular weight made in vivo.
Structural analysis of virion proteins of the avian coronavirus infectious bronchitis virus
Authors: Stern D F , Burgess L , Sefton B M
Published: January 2020

We have found six major polypeptides in virions of the avian coronavirus infectious bronchitis virus grown in tissue culture: four glycoproteins, GP84, GP36, GP31, and GP28, and two non-glycosylated proteins, P51 and P23. In addition, we detected three minor species: two glycoproteins, GP90 and GP59, and one non-glycosylated protein, P14. Two-dimensional tryptic peptide mapping showed that GP36, GP31, GP28, and P23 comprise a group of closely related proteins which we have designated the "P23 family," but that the other proteins are distinct. Analysis by partial proteolytic digestion of P23 family, but that the other proteins are distinct. Analysis by partial proteolytic digestion of the P23 family labeled biosynthetically with [35S] methionine, and P23, labeled with [35S] formyl-methionine by in vitro translation of RNA from infected cells, revealed that the proteins of the P23 family differ in their amino-terminal domains. Similar analysis of GP31 and Gp36 labeled with [3H] mannose showed that the partial proteolytic fragments unique to these proteins were glycosylated. This suggests that differences in glycosylation in the amino-terminal domains contributes to the marked polymorphism os the P23 family. The results are discussed with respect to possible models for synthesis of the virion proteins.
Electron microscopic study of equine herpesvirus type 1 DNA
Authors: Ruyechan W T , Dauenhauer S A , O'Callaghan D J
Published: January 2020

Electron microscopic studies of equine herpesvirus DNA revealed that single strands that were allowed to reanneal formed single-stranded loops with double-stranded stems only at one end of the molecule. These observations support restriction enzyme analyses which indicate that the 92-megadalton DNA molecule exists as a long region of unique sequences covalently linked to a short region. The short region is comprised of an internal unique sequence, which forms the loop during reannealing of single strands, and two terminal inverted repeat sequences that bracket the unique sequence and form the double-stranded stem structure observed upon reannealing of single strands. Measurements of the unique sequence and terminal inverted repeat subgenomic sequences indicate a size of 6.4 megadaltons for each and thus fix the size of the short region at approximately 19.2 megadaltons.
Mechanism of replication of bacteriophage phi X174 XIX. Initiation of phi X174 viral strand DNA synthesis at internal sites on the genome
Authors: Matthes M , Weisbeek P J , Denhardt D T
Published: January 2020

Bacteriophage phi X174 viral strand DNA molecules shorter than genome length found late in the infectious cycle in Escherichia coli were 5' end labeled with 32P. Hybridization of the 32P-labeled molecules to restriction enzyme fragments of phi X replicative form DNA revealed an excess of phi X molecules whose 5' ends mapped in HaeIII fragments Z3 and Z4 in comparison with fragments Z1 and Z2. This suggests that initiation of phi X174 viral strand DNA synthesis may occur at internal sites on the complementary strand. There are several appropriately located sequences that might serve as n' (factor Y) recognition sequences and thereby facilitate discontinuous synthesis of the viral strand.
Linear mapping of tryptophan residues in Vesiculovirus M and N proteins by partial chemical cleavage
Authors: Brown E , Prevec L
Published: January 2020

Nonlimit chemical cleavage at tryptophan residues of protein labeled at the amino terminus afforded a simple procedure for generating specific fragments and for mapping tryptophan positions. A comparison of the matrix (M) and nucleocapsid (N) proteins of four members of the Vesiculovirus group by this procedure suggests considerable conservation of tryptophan number and location in the four serotypes examined.
NS phosphoprotein of vesicular stomatitis virus: subspecies separated by electrophoresis and isoelectric focusing
Authors: Hsu C H , Kingsbury D W
Published: January 2020

The NS protein of vesicular stomatitis virus is the only phosphorylated nucleocapsid protein. The amount of NS phosphorylation appears to regulate the activity of the protein in the transcription of the virus genome. Several methods have been used to separate NS subspecies containing different amounts of phosphate, but the relationships among the subspecies separated by different workers have been unclear. We report that the isoelectric points of NS molecules were abnormally acidic in some commercial ampholytes, but favorable ampholytes resolved multiple phosphorylated NS subspecies with isoelectric points ranging from pH 6.8 to 7.2. The most highly phosphorylated NS molecules had more acidic isoelectric points, and they exhibited greater electrophoretic mobilities in two previously employed electrophoretic systems.
Nucleotide Sequence of the Akv
env
Gene
Authors: Lenz Jack , Crowther Robert , Straceski Anthony , Haseltine William
Published: January 2020

The sequence of 2,191 nucleotides encoding the
env
gene of murine retrovirus Akv was determined by using a molecular clone of the Akv provirus. Deduction of the encoded amino acid sequence showed that a single open reading frame encodes a 638-amino acid precursor to gp70 and p15E. In addition, there is a typical leader sequence preceding the amino terminus of gp70. The locations of potential glycosylation sites and other structural features indicate that the entire gp70 molecule and most of p15E are located on the outer side of the membrane. Internal cleavage of the
env
precursor to generate gp70 and p15E occurs immediately adjacent to several basic amino acids at the carboxyl terminus of gp70. This cleavage generates a region of 42 uncharged, relatively hydrophobic amino acids at the amino terminus of p15E, which is located in a position analogous to the hydrophobic membrane fusion sequence of influenza virus hemagglutinin. The mature polypeptides are predicted to associate with the membrane via a region of 30 uncharged, mostly hydrophobic amino acids located near the carboxyl terminus of p15E. Distal to this membrane association region is a sequence of 35 amino acids at the carboxyl terminus of the
env
precursor, which is predicted to be located on the inner side of the membrane. By analogy to Moloney murine leukemia virus, a proteolytic cleavage in this region removes the terminal 19 amino acids, thus generating the carboxyl terminus of p15E. This leaves 15 amino acids at the carboxyl terminus of p15E on the inner side of the membrane in a position to interact with virion cores during budding. The precise location and order of the large RNase T
1
-resistant oligonucleotides in the
env
region were determined and compared with those from several leukemogenic viruses of AKR origin. This permitted a determination of how the differences in the leukemogenic viruses affect the primary structure of the
env
gene products.
Construction of a cloned library of the EcoRI fragments from the human cytomegalovirus genome (strain AD169)
Authors: Tamashiro J C , Hock L J , Spector D H
Published: January 2020

The DNA genome of human cytomegalovirus (HCMV) strain AD169 is 158 x 10(6) Mr. Cleavage of the HCMV DNA with the restriction endonuclease EcoRI yields 35 major fragments ranging in size from 0.54 x 10(6) Mr. We have constructed a cloned library of the EcoRI fragments of this strain of HCMV, using the plasmid pACYC184 and the recipient bacterium Escherichia coli strain HB101 RecA-. The viral origin of the cloned inserts was determined by hybridization to viral DNA. The fragments were characterized further by digestion with other restriction enzymes. Several clones were obtained which contained sequences spanning the junction between the long (L) and short (S) components of the viral DNA sequences. These clones differed in molecular weight by multiples of 0.3 x 10(6) to 0.4 x 10(6) Mr. The variability found in the clones was also reflected in the genome. Each clone containing a junction sequence hybridized to a series of bands on Southern filters of EcoRI-digested HCMV DNA. This "ladder effect" provided evidence for a region of heterogeneity within the L-S junction.
Expression of the Bottom-Component RNA of Cowpea Mosaic Virus: Evidence that the 60-Kilodalton VPg Precursor Is Cleaved into Single VPg and a 58-Kilodalton Polypeptide
Authors: Goldbach Rob , Rezelman Geertje , Zabel Pim , van Kammen Albert
Published: January 2020

In cowpea protoplasts infected with cowpea mosaic virus, a bottom-component (B) RNA-encoded 60-kilodalton (60K) polypeptide is synthesized, which is membrane-bound and represents the direct precursor to the genome-bound protein VPg. The relationship between this VPg precursor and other B-RNA-encoded polypeptides was studied. Digestion of the B-RNA-encoded 170K and 84K polypeptides with
Staphylococcus aureus
protease V8 and subsequent analysis of the generated peptides with antiserum against VPg showed that a VPg sequence resides internally in these polypeptides. Furthermore, a new B-RNA-encoded polypeptide was detected, with a size of 58K, which differed from the 60K polypeptide only in the lack of VPg sequences. A model is presented in which the 60K VPg precursor is generated from the 200K primary translation product from B RNA and further processed to a 58K polypeptide and single VPg.
Dependence of tumor-forming capacities of cells transformed by recombinants between adenovirus types 5 and 12 on expression of early region 1
Authors: Shiroki K , Maruyama K , Saito I , Fukui Y , Yazaki K , Shimojo H
Published: January 2020

Recombinants between an adenovirus type 5 (Ad5) deletion mutant and the Ad12 DNA fragment containing early region 1 (E1) were isolated from cells cotransfected with the EcoRI-C fragment of Ad12 DNA and Ad5 dl312 (deletion in E1A) DNA (rcA) and from cells cotransfected with the SalI-C fragment of Ad12 DNA and Ad5 dl312 DNA (rcB). No recombinant was isolated from cells cotransfected with Ad5 dl313 (deletion in E1B) DNA and restriction fragments of Ad12 DNA. Both rcA and rcB are defective and able to replicate in human embryo kidney (HEK) and KB cells with complementation by dl312. Both rcA and rcB formed Ad12 T antigen g, but not T antigen f, in infected HEK and KB cells. In rcA- and rcB-infected cells, Ad5 E1B and Ad12 E1A genes are transcribed. Heteroduplex and size analyses of rcA-1 or rcB-1 DNA fragments hybridized with Ad12 DNA revealed that rcA-1 DNA has a deletion between 5 and 15 map units with an insertion of a portion of Ad12 DNA (10%) and that rcB-1 DNA has a deletion between 70 and 80 map units with an insertion of a portion of Ad12 DNA (10%). The transformed cell lines, RCAY and RCBY, were established after infection of rat 3Y1 cells with rcA and rcB, respectively. Both Ad5 and Ad12 DNA sequences are contained in these cells. In RCAY cells, Ad12 T antigen g is detected, but Ad12 T antigen f is not. In RCBY cells, both Ad12 T antigen g and f are detected. Only the Ad12 E1A gene is transcribed in RCAY cells, whereas Ad5 E1B, Ad12 E1A, and Ad12 E1B genes are transcribed in RCBY cells. In soft-agar cultures, RCBY cells form large colonies, whereas RCAY cells form only tiny colonies. RCBY cells form tumors as efficiently as 12WY cells in transplanted rats. RCAY cells formed tumors inefficiently. Ad5-transformed 5WY cells do not form tumors. These observations indicate that the efficient tumor formation by RCBY cells is dependent on the expression of the Ad12 E1A and E1B genes, whereas the inefficient tumor formation by RCAY cells is due to the expression of only the Ad12 E1A gene.