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growth complementation of influenza virus temperature-sensitive mutants in mouse cells which express the rna polymerase and nucleoprotein genes.in order to establish cell lines which complement the growth of temperature-sensitive (ts) mutants of influenza virus, three rna polymerase and nucleoprotein (np) genes each linked to the mouse mammary tumor virus ltr were cloned into the bovine papillomavirus vector dna. after co-transfection of mouse c127 cells with these recombinant plasmids, a cell line, clone 76, in which the expression of the three polymerase and np genes could be stimulated by dexamethasone, was established. the clone 76 ...19911663110
transactivation of heterologous promoters by hiv-1 tat.to determine whether hiv-1 tat can transactivate a heterologous promoter lacking hiv sequences other than the tar element, tar was placed downstream of the chicken beta-actin promoter. tat increased expression directed by the actin-tar promoter to a degree equal to tat induction of the hiv-1 ltr. optimal transactivation was observed when tar was positioned downstream of the actin promoter such that the expected cap site of transcripts from this promoter would be the same as in transcripts direct ...19911662814
enhancer effect of bovine papillomavirus e2 protein in replication of polyomavirus dna.in polyomavirus, both transcription from the early promoter and viral dna replication initiated at the origin of dna replication is controlled by binding of proteins to the enhancer region. we have developed a simple model system to study the role of an enhancer binding factor in the initiation of polyomavirus dna replication. a reporter plasmid was constructed which has the enhancer region replaced by two binding sites for a transcription factor, the e2 protein encoded by bovine papillomavirus ...19911662803
relationship of histone acetylation to dna topology and transcription.an autonomously replicating plasmid constructed from bovine papiloma virus (bpv) and pbr322 was stably maintained as a nuclear episome in a mouse cell culture. addition to a cell culture of sodium butyrate (5 mm) induced an increase in plasmid dna supercoiling of 3-5 turns, an increase in acetylation of cellular histones, and a decrease in plasmid transcription by 2- to 4-fold. after withdrawal of butyrate, dna supercoiling began to fluctuate in a wave-like manner with an amplitude of up to 3 tu ...19911662766
identification of the origin of replication of bovine papillomavirus and characterization of the viral origin recognition factor e1.expression of the viral polypeptides e1 and e2 is necessary and sufficient for replication of bpv in mouse c127 cells. by providing these factors from heterologous expression vectors we have identified a minimal origin fragment from bpv that contains all the sequences required in cis for replication of bpv in short term replication assays. this same sequence is also required for stable replication in the context of the entire viral genome. the identified region is highly conserved between differ ...19911661672
[recombinant murine cell lines transformed by various vectors based on bovine papillomavirus type 1 and expressing human tissue plasminogen activator].we have constructed a number of vectors which include transcriptional unit of human tpa cdna and 100% bpv-1 dna or 100% lx dna (mutant bpv variant with tandem duplication of lcr-e6-e7 region). additional hsv-1 tk-promoter was inserted in the flanks of viral dnaa in a set of constructions. a number of recombinant cell lines have been established by means of transformation using the constructed vectors. the increased focus formation activity and the improved vector properties were demonstrated for ...19911661373
high rotational mobility of dna in animal cells and its modulation by histone acetylation.dna rotational mobility in a bovine papilloma virus (bpv)-based minichromosome, autonomously replicating in mouse cells, was studied using topoisomer analysis in temperature shift experiments. it was found that in live cells the average number of topological turns increased by six in the course of temperature shift through a range of 37 degrees c. this comprised approximately 85% of the total potential mobility of naked plasmid dna. dna rotation in isolated nuclei was found to be 3.5-4.0 turns p ...19911661371
cell transformation induced by bovine papillomavirus dna as an assay for tumor promoters and chemopreventive agents.an in vitro assay was designed to examine and quantitate the action of chemical promoters and chemopreventive agents on papillomavirus dna-carrying cells. cultured c3h/10t1/2 cells transfected with bovine papillomavirus type 1 dna (plasmid pdbpv-1) were used as targets, and the frequency of transformed foci was used as an endpoint. the development of foci with a transformed phenotype was greatly enhanced by tumor promoters (e.g., mezerein, 12-o-tetradecanoyl-phorbol-13-acetate, teleocidin, and o ...19911661204
efficient selection for high-expression transfectants with a novel eukaryotic vector.we have developed a new expression vector which allows efficient selection for transfectants that express foreign genes at high levels. the vector is composed of a ubiquitously strong promoter based on the beta-actin promoter, a 69% subregion of the bovine papilloma virus genome, and a mutant neomycin phosphotransferase ii-encoding gene driven by a weak promoter, which confers only marginal resistance to g418. thus, high concentrations of g418 (approx. 800 micrograms/ml) effectively select for t ...19911660837
the bovine papillomavirus e5 oncogene can cooperate with ras: identification of p21 amino acids critical for transformation by c-rash but not v-rash.we have previously used a series of insertion-deletion mutants of the mutationally activated v-rash gene to identify several regions of the encoded protein that are dispensable for cellular transformation (b. m. willumsen, a. g. papageorge, h.-f. kung, e. bekesi, t. robins, m. johnsen, w. c. vass, and d. r. lowy, mol. cell. biol. 6:2646-2654, 1986). to determine if some of these amino acids are more important for the biological activity of c-rash, we have now tested many of the same insertion-de ...19911658623
tumorigenic transformation of murine keratinocytes by the e5 genes of bovine papillomavirus type 1 and human papillomavirus type 16.to examine the biological properties of the bovine papillomavirus type 1 (bpv) and human papillomavirus type 16 (hpv16) e5 genes, each was cloned separately into a retroviral expression vector and helper-free recombinant viruses were generated in packaging cell lines. the bpv e5 retroviruses efficiently caused morphologic and tumorigenic transformation of cultured lines of murine fibroblasts, whereas the hpv16 e5 viruses were inactive in these assays. in contrast, infection of the p117 establish ...19911658398
bovine papillomavirus with a mutation in the e2 serine 301 phosphorylation site replicates at a high copy number.the e2 open reading frame of bovine papillomavirus type 1 (bpv-1) encodes at least three proteins with transcriptional regulatory properties. the full-length e2 open reading frame encodes a transcriptional transactivator, and the 3' region encodes two smaller polypeptides that repress e2-mediated transactivation. the full-length gene product is also required for viral dna replication. we have demonstrated that the bpv-1 e2 polypeptides are phosphorylated primarily on two serine residues at a sit ...19911658358
native yeast telomeres are sufficient to stabilize linear dna in xenopus laevis oocytes.we have constructed a linear plasmid in yeast containing the entire bovine papillomavirus genome and tested its physical stability following microinjection into stage vi oocytes of xenopus laevis. our results show that unmodified telomeres, in contrast to the yeast-passaged telomeres, drastically affect the stability of the injected linear plasmid. plasmids carrying unmodified tetrahymena thermophila telomeric sequences are rapidly degraded in oocytes. when these plasmids are passed through yeas ...19911657721
activation of bpv-1 replication in vitro by the transcription factor e2.soluble extracts from uninfected murine cells supplemented with purified viral e1 and e2 proteins support the replication of exogenously added papilloma virus dna. the e2 transactivator stimulates the binding of the e1 replication protein to the minimal origin of replication and activates dna replication. these results support the concept that transcription factors have a direct role in the initiation of dna replication in eukaryotes by participating in the assembly of a complex at the origin of ...19911656277
regulation of early gene expression from the bovine papillomavirus genome in transiently transfected c127 cells.expression of bovine papillomavirus (bpv) early gene products is required for viral dna replication and establishment of the transformed phenotype. by the use of a highly efficient electroporation system, we have examined for the first time the transcriptional activity of bpv promoters in their natural genomic context in a replication-permissive cell line. we have determined that a qualitatively distinct stage of transcription is not detectable prior to dna replication in transiently transfected ...19911656065
sequencing data on the long control region of human papillomavirus type 16.a one base change (adenine at position 7861) in the long control region (lcr) of the prototype sequence of human papillomavirus type 16 was reported. with this correction, a new e2-binding site was revealed, 111 bp and 143 bp upstream from the tata box and p97, respectively, and 105 bp downstream of the keratinocyte-dependent enhancer. an a to c mutation at position 41 was found in a patient with invasive carcinoma. this mutation falls within an e2-binding site.19911655963
the papillomavirus e2 regulatory proteins. 19911655748
several different upstream promoter elements can potentiate transactivation by the bpv-1 e2 protein.the enhancer and upstream promoter regions of rna polymerase ii transcribed genes modulate the rate of transcription initiation and establish specific patterns of gene expression. both types of region consist of clusters of dna binding sites for nuclear proteins. to determine how efficiently the same factor can activate transcription when acting as an enhancer or promoter factor, we have studied transactivation by the bpv-1 e2 protein, a papillomavirus transcriptional regulator. by cotransfectin ...19911655407
[comparison of vector properties of the usual and modified sequences of the bpv-1 genome]. 19911655372
the b subgroup bovine papillomaviruses lack an identifiable e6 open reading frame.analysis of the corrected dna sequence for the bovine papillomavirus type 4 (bpv4) genome revealed that there is no open reading frame (orf) that might encode an e6 protein. the other two b subgroup bovine papillomaviruses, bpv3 and bpv6, were found to have the same arrangement of orfs in this region as bpv4. thus, we conclude that e6 functions are either not required by these viruses or are performed by another viral (or host) protein. furthermore, the position that might be expected to be occu ...19911654923
a bovine papillomavirus e1-related protein binds specifically to bovine papillomavirus dna.the e1 open reading frame of bovine papillomavirus (bpv) was expressed as a reca-e1 fusion protein in escherichia coli. the bacterially expressed reca-e1 protein exhibited sequence-specific dna binding activity; strong binding to the region from nucleotides 7819 to 93 on the bpv genome (designated region a) and weak binding to the adjacent region from nucleotides 7457 to 7818 (region b) were observed. the interaction between the bpv-derived reca-e1 protein and region a appeared to be highly spec ...19911654443
immunofluorescent detection of bovine papillomavirus e4 antigen in the cytoplasm of cells permissive in vitro for viral dna amplification.the e4 gene of several human papillomavirus types is expressed in association with vegetative viral dna synthesis in differentiated epidermal cells. to develop reagents to study expression of the bovine papillomavirus type 1 (bpv-1) e4 gene in warts and in virus-transformed cell lines, rabbit polyclonal antiserum was raised to the bpv-1 e4 antigen produced as a fusion polypeptide in escherichia coli. by immunoblotting analysis of productively infected bovine fibropapilloma tissue, e4-related pro ...19911654378
[implantation of genetically manipulated fibroblasts into mice as a model of gene therapy--supplementations of human granulocyte colony-stimulating factor (hg-csf) and interferon-alpha (ifn-alpha)].implantation of genetically manipulated fibroblasts is now coming considered to be one of the important methods for gene therapy. before the clinical application of this method, we still need to resolve several problems encountered. we have recently developed a model system for the fibroblast-mediated cytokine supplementation gene therapy. bmgneo (bovine papilloma virus-derived plasmid) (gifted from dr. karasuyama) was used for expression of hg-csf cdna or hifn-alpha cdna (gifted from dr. nagata ...19911653596
the functional bpv-1 e2 trans-activating protein can act as a repressor by preventing formation of the initiation complex.the products encoded by the e2 open reading frame of the papillomaviruses are dna-binding transcription factors involved in the positive or negative regulation of multiple viral promoters. to further understand the mechanisms by which the same transcription factor may act differentially, the full-length bpv-1 e2 protein was expressed and purified from yeast and assayed in vitro for its capacity to modulate transcription. e2 stimulated transcription of the hsv thymidine kinase (tk) promoter when ...19911653173
two dna-bound e2 dimers are required for strong transcriptional activation and for cooperation with cellular factors in most cells.the e2 transcriptional activator encoded by papillomaviruses binds as a dimer to the palindromic sequence accgnnnncggt present in several copies in the viral genomes. we show that strong activation requires that a minimum of two e2 binding sites are actually occupied by the protein. studies with constructs bearing two e2 sites separated by variable lengths of dna showed that there is no stereospecific constraint for e2 homosynergy. the capacity of e2 to cooperate with cellular factors interactin ...19911653009
illegitimate recombination in a bovine papillomavirus shuttle vector: a high level of site specificity.recombination in a bovine papillomavirus shuttle vector carrying direct repeats of moloney murine leukemia virus ltr sequence was examined. differently from similar vectors carrying direct repeats of sv40 polya addition signal or neomycin resistance gene, the vector exhibited no homologous recombination between the repeats. instead, illegitimate recombination took place. there were two major types of recombination products from the restriction cleavage pattern. the plasmids in independent cellul ...19911652950
[detection of bovine papillomavirus dna in equine sarcoids using the polymerase chain reaction (pcr)].unfixed and formalin-fixed frozen sections and paraffin-sections of histopathologically confirmed sarcoids of 20 horses were studied in the pcr. the used set of primers was located in the e5 open reading frame fitting both to bovine papillomavirus 1 (bpv-1) and bpv-2. independent of the quality of the used tissues bpv-dna was detected in all 20 sarcoids. by cleaving with restriction endonuclease bst xi it was shown that the dna-sequences amplified by pcr were identical with that of bpv-1. the re ...19911652932
studies on vaccination against papillomaviruses: prophylactic and therapeutic vaccination with recombinant structural proteins.the l1 and l2 proteins of bpv-2 have been produced in escherichia coli as beta-galactosidase fusion proteins. the fusion proteins have been used to vaccinate calves both prophylactically and therapeutically. the l1 fusion protein prevented tumor formation when administered before challenge with bpv-2, while the l2 fusion protein was very effective in promoting tumor rejection, independently from whether it was administered before or after challenge. animals vaccinated with l1, but not with l2, r ...19911651594
biological properties of the deer papillomavirus e5 gene in mouse c127 cells: growth transformation, induction of dna synthesis, and activation of the platelet-derived growth factor receptor.we determined the biological activities of the 44-amino-acid deer papillomavirus (dpv) e5 protein in mouse c127 cells. the dpv e5 gene can induce focus formation, stable and acute morphologic transformation, and dna synthesis, and it activates the platelet-derived growth factor (pdgf) beta receptor as assessed by increased constitutive tyrosine phosphorylation of mature and precursor receptor forms. thus, the dpv e5 protein has biological activities similar to those of the closely related e5 pro ...19911651413
initiation of transcription from the minute virus of mice p4 promoter is stimulated in rat cells expressing a c-ha-ras oncogene.transformation of fr3t3 rat fibroblasts by a c-ha-ras oncogene but not by bovine papillomavirus type 1 is associated with an increase in the abundance of mrnas from prototype strain mvmp of infecting minute virus of mice, an oncosuppressive parvovirus. this differential parvovirus gene expression correlates with the reported sensitization of ras- but not bovine papillomavirus type 1-transformed cells to the killing effect of mvmp (n. salomé, b. van hille, n. duponchel, g. meneguzzi, f. cuzin, j. ...19911651412
in vitro interactions between bovine papillomavirus and human monocytes and macrophages.limited data suggest that macrophages play a role in the pathogenesis of bovine papillomavirus (bpv) infections. in the present study, interactions between these cells and bpv-1 were explored by exposing in vitro human blood monocytes and monocyte-derived macrophages to purified virions. immediately or up to 28 days after exposure, cell culture supernatants as well as cell lysates were collected. interleukin 1 activity was detected in the supernatants of monocytes early after exposure to bpv (0- ...19911650765
characterization of bpv-like dna in equine sarcoids.the dna from equine sarcoid samples from new york state and switzerland was isolated and probed with bovine papillomavirus type 1 (bpv-1) to determine if bpv genomes were present. twelve of 13 sarcoids from new york state and 17/20 sarcoids from switzerland contained dna that hybridized to the bpv-1 probe. restriction enzyme analysis of the positive samples demonstrated restriction fragment profiles characteristic of bpv-1 in 22 sarcoids and restriction fragment profiles characteristic of bovine ...19911650553
in vitro "progression" of bovine papillomavirus-transformed cells: loss of contact sensitivity after multiple rounds of selection.the transformed phenotype of c127 cells harboring bovine papillomavirus shuttle vector pdbpvmmt neo(342-12) was suppressed by direct contact with untransformed c127 cells. by repeated selections of rare foci developing on untransformed cell monolayers, we obtained a cellular clone of bpv transformants which formed foci on the untransformed c127 cells as efficiently as on plastic surface. the bpv genome in the mutant cells showed extensive genetic rearrangements, duplication of upstream regulator ...19911650331
expression of epidermal growth factor precursor cdna in animal cells.this chapter outlines in detail the optimal conditions for the expression of human recombinant proteins in mouse cells using a bovine papillomavirus-based mammalian expression vector. the procedures we have described were used to successfully express high levels of the human egf precursor in our laboratory and the human insulin receptor in the laboratory of whittaker. using this experimental approach we were able to demonstrate that expression of a cdna for prepro-egf produces a glycosylated mem ...19911649948
bovine papillomavirus e5 oncoprotein binds to the 16k component of vacuolar h(+)-atpases.the major transforming protein of bovine papillomavirus type 1, e5, is mainly associated with endomembranes, specifically binding to a cellular protein of relative molecular mass 16,000 (16k). at the same time as transformation, e5 causes the phosphorylation of tyrosine residues in epidermal and platelet-derived growth factor receptors. we show here that the 16k protein associated with e5 is the 16k component of vacuolar atpases. this protein is known to be an integral membrane protein in endoso ...19911649407
formation of the complex of bovine papillomavirus e1 and e2 proteins is modulated by e2 phosphorylation and depends upon sequences within the carboxyl terminus of e1.the 68-kda bovine papillomavirus (bpv) type 1 replication protein e1 and the 48-kda transactivator protein e2 form a complex that specifically binds dna [mohr, i.j., clark, r., sun, s., androphy, e.j., macpherson, p. & botchan, m.r. (1990) science 250, 1694-1699]. we have confirmed this observation and shown that the e1-e2 complex binds to dna fragments that contain the bpv plasmid maintenance sequence 1 and a site for the initiation of bidirectional bpv dna synthesis. the e1 protein was found t ...19911648739
topological properties of bovine papillomavirus type 1 (bpv-1) dna in episomal nucleoprotein complexes: a model system for chromatin organization in higher eukaryotes.sedimentation analysis of isolated episomal bovine papillomavirus type 1 (bpv-1) nucleoprotein complexes in sucrose gradients and subsequent separation of the purified dna in chloroquine gels revealed different classes of molecules, varying in their degree of superhelicity. since torsionally stressed dna favors the adoption of secondary structures, we employed the single-strand-specific s1 nuclease to detect such structural alterations in both naked dna and native chromatin. direct examination o ...19911648363
[papillomatosis of cattle and its relationship to equine sarcoid].the aetiology and the pathogenesis of equine sarcoids are described. aspects of therapy are discussed.19911646494
bovine papillomavirus type 1 alters the processing of host glucose- and calcium-modulated endoplasmic reticulum proteins.we have previously characterized five proteins induced by the presence of the e2 open reading frame (orf) region of bovine papillomavirus type 1 (bpv-1) in c127 mouse fibroblasts (r. m. levenson, u. g. brinckmann, m. k. o'banion, e. j. androphy, j. t. schiller, f. tabatabai, l. p. turek, k. neary, m. t. chin, t. r. broker, l. t. chow, and d. a. young, virology 172:170-179, 1989). by specific immunoprecipitation, we now find that one of the papillomavirus-associated proteins (pvp1) is a highly gl ...19911645780
papillomavirus dna replication. 19911645776
genital bovine papillomavirus infection in saudi arabia.genital bovine papillomavirus infection was observed for the first time in the al-ahsa region of saudi arabia. the disease involved 1 female and 2 male 2-4-year-old crossbred cattle. fibropapillomas (warts) were limited to the prepuce and vulva. electron micrographs of thin sections of the lesions revealed the presence of intranuclear viruslike particles. using a broadly cross-reactive rabbit polyclonal antiserum directed against papillomavirus group-specific antigens, the infection was confirme ...19911645597
functional analysis of e2-mediated repression of the hpv18 p105 promoter.transcription of the transforming genes e6 and e7 of the human papillomavirus type 18 (hpv18) can be repressed by the product of the e2 open reading frame. mutations were introduced in the cis-responsive elements upstream from the e6 and e7 transcriptional promoter, p105. the effect of these mutations in the absence or presence of e2 was examined in the human cervical carcinoma cell line c33, transfected with expression plasmids. in the presence of hpv18 e2, repression was relieved only when bot ...19911645591
analysis of the influences of the e5 transforming protein on kinetic parameters of epidermal growth factor binding and metabolism.the e5 protein of the bovine papillomavirus induces cellular transformation when transfected into nih 3t3 cells, and the extent of focal transformation is enhanced by cotransfection with the epidermal growth factor (egf) receptor (martin et al., cell 59:21-32, 1989). to determine whether e5 affects egf:receptor interactions we analyzed the kinetics of 125i-egf processing using a mathematical model that enabled us to evaluate rate constants for ligand association (ka), dissociation (kd), internal ...19921639860
transcription factors junb and c-jun are selectively up-regulated and functionally implicated in fibrosarcoma development.bovine papillomavirus transgenic mice develop skin tumors arising from dermal fibroblasts in a process comprised of three distinctive stages: mild and aggressive fibromatoses, and fibrosarcoma. in both tissue biopsies and derivative cell lines, the proto-oncogenes junb and c-jun are induced in the latter two stages, in contrast to jund and fos. fibrosarcoma cell lines have increased ap-1 dna-binding activity. overexpression of junb or c-jun by transfection into the mild fibromatosis stage elicit ...19921459456
the bpv-1 e5 oncoprotein expressed in schizosaccharomyces pombe exhibits normal biochemical properties and binds to the endogenous 16-kda component of the vacuolar proton-atpase.the 44-amino-acid e5 oncoprotein of bovine papillomavirus type 1 transforms immortalized murine fibroblast cell lines. this highly hydrophobic protein forms homodimers, localizes to intracellular membrane compartments (including the golgi apparatus), and forms a complex with the 16-kda membrane-embedded constituent (16k) of the vacuolar proton-atpase. to develop a system for the genetic and biochemical analysis of the e5/16k interaction, the e5 gene was cloned into a new vector which was designe ...19921387753
levels of immunoglobulin g antibodies against defined epitopes of the l1 and l2 capsid proteins of human papillomavirus type 6 are elevated in men with a history of condylomata acuminata.sera from 159 men attending the sexually transmitted disease clinic at karolinska hospital, stockholm, sweden, were analyzed for the presence of immunoglobulin a (iga) and igg antibodies to a panel of synthetic peptides derived from the e2, l1, and l2 regions of the human papillomavirus types 1 (hpv 1), 6, 8, 11, 16, 18, 31, and 33. the study subjects were divided into three groups: (i) asymptomatic men with no history of genital warts who served as controls, (ii) men with visible condylomata, a ...19921378454
a glutamine residue in the membrane-associating domain of the bovine papillomavirus type 1 e5 oncoprotein mediates its binding to a transmembrane component of the vacuolar h(+)-atpase.the 44-amino-acid e5 oncoprotein is the major transforming protein of bovine papillomavirus type 1. it is a highly hydrophobic polypeptide which dimerizes and localizes to the golgi apparatus and endoplasmic reticulum membranes. recent evidence suggests that e5 modulates the phosphorylation and internalization of the epidermal growth factor and colony-stimulating factor 1 receptors and constitutively activates platelet-derived growth factor receptors in c127 and fr3t3 cells. although no direct i ...19921370089
growth of transformed c-127 cell in bioreactors for large-scale t-pa production. 19911369332
chemical modifications to improve uptake and bioavailability of antisense oligonucleotides. 19921364095
comparative analysis of inositol phospholipid metabolism in viral and chemical transformation of mammalian cells.1. inositol phospholipid metabolites were measured from virally and chemically transformed cells. 2. increased levels of pip and pip2 were observed from both transformed cell lines as compared with controls. 3. intracellular levels of ip3 were also increased approximately three folds in bpv-1 infected id 13 cells and in 3-mc transformed nih 3t3 cells. 4. the results suggest that phosphorylation of phosphatidylinositols and enhanced generation of ip3 second messenger molecules are the common sign ...19921360364
the efficiency and timing of plasmid dna replication in xenopus eggs: correlations to the extent of prior chromatin assembly.injection of the circular plasmid fv1 (derived from type i bovine papilloma virus) into xenopus eggs before the start of the first cell cycle dramatically increases the efficiency of plasmid replication once eggs are chemically activated. we call this the preloading effect and report kinetic and quantitative characterization of this phenomenon here. the timing and the amount of fv1 synthesis were measured by both brdutp density labelling and an optimized method of selective enzymatic digestion o ...19921336780
inducible expression bovine papillomavirus shuttle vectors containing ferritin translational regulatory elements.the combination of transcriptional and translational control elements in an inducible expression vector suitable for use in stably transformed cell lines was explored. to this end, ferritin translational control elements have been inserted downstream from a mouse metallothionein (mmt-i) transcriptional promoter (pmmt-i), and upstream from various reporter protein-encoding open reading frames (orfs), all carried on a bovine papillomavirus shuttle vector. protocols which stimulate transcription (w ...19921336755
interaction with the nuclear matrix of a chimeric construct containing a replication origin and a transcription unit.we have studied the interaction of a chimeric construct containing an origin of replication (from bovine papilloma virus) and a hormonally regulated transcription unit (long terminal repeat from the mouse mammary tumor virus, driving the v-ha-ras gene) with the nuclear scaffold and matrix from mouse fibroblasts. we used two experimental approaches because the nuclear matrix protein composition depends largely on the isolation conditions, making its definition mostly operational. in situ studies ...19921336395
does cruciform dna provide a recognition signal for dna-topoisomerase ii?topoisomerase ii displays higher affinity for supercoiled dna compared to the same relaxed dna. moreover, cruciform structures are formed in topologically constrained dna. here we report that, using s1 nuclease experiments on supercoiled dna, hairpin structures are located close to numerous topoisomerase ii cleavage sites on the bpv i genome. therefore, dna secondary structure may play a role in the recognition mechanism of dna by topoisomerase ii.19921335757
acquisition of interleukin-3 independence in fdc-p2 cells after transfection with the activated c-h-ras gene using a bovine papillomavirus-based plasmid vector.since the ras family of proto-oncogenes is supposed to be involved in leukemogenesis by point-mutational activation, we studied the effect of the activated ras gene on the growth of a murine interleukin-3 (il-3)-dependent cell line, fdc-p2. the human activated c-h-ras gene was transfected into fdc-p2 cells by electroporation using a high-level expression vector, bmghph, which contains a partial dna sequence from bovine papillomavirus (bpv) and a hygromycin b (hmb)-resistant gene as a selectable ...19921334732
papillomavirus l1 major capsid protein self-assembles into virus-like particles that are highly immunogenic.infection by certain human papillomavirus types is regarded as the major risk factor in the development of cervical cancer, one of the most common cancers of women worldwide. analysis of the immunogenic and structural features of papillomavirus virions has been hampered by the inability to efficiently propagate the viruses in cultured cells. for instance, it has not been established whether the major capsid protein l1 alone is sufficient for virus particle assembly. in addition, it is not known ...19921334560
the bpv-1 e5 protein, the 16 kda membrane pore-forming protein and the pdgf receptor exist in a complex that is dependent on hydrophobic transmembrane interactions.the e5 oncoprotein of bovine papillomavirus type 1 is a 44 amino acid, highly hydrophobic protein that induces the stable transformation of immortalized murine fibroblasts, presumably through its activation of growth factor receptors. previous studies have shown that the e5 protein complexes with the 16 kda (16k) pore-forming protein of vacuolar h(+)-atpases. this integral membrane protein is essential for the acidification and function of subcellular compartments that process growth factor rece ...19921334459
the e2 binding sites determine the efficiency of replication for the origin of human papillomavirus type 18.human papillomaviruses (hpv-s) have been shown to possess transforming and immortalizing activity for many different, mainly keratinocyte cell lines and they have been detected in 90% of anogenital cancer tissues, which suggests a causative role in the induction of anogenital and other tumours. we have exploited a quantitative assay to identify and characterize the origin of replication of the human papillomavirus type 18 (hpv-18), one of the most prevalent types in the high-risk hpv group. repl ...19921334259
association of bovine papillomavirus type 2 and bracken fern with bladder cancer in cattle.the bladder cancer syndrome that often accompanies chronic enzootic hematuria in cattle grazing on pastures infested by bracken fern has been experimentally reproduced in animals fed a diet of bracken. the experimentally induced tumors were histologically and pathologically indistinguishable from the naturally occurring ones and comprised two main types: (a) carcinoma of the urothelium identical to that seen in humans; and (b) hemangioendotheliomas of the subjacent capillaries. often the two typ ...19921333885
properties of bovine papillomavirus e1 mutants.ostensibly comparable mutants of bovine papillomavirus type 1 (bpv-1) affecting the e1 open reading frame that were constructed in several laboratories have been reported to exhibit either reduced or increased transformation efficiencies in established mouse cell lines relative to wild-type bpv-1 dna. to resolve these discrepancies, we have reexamined many of the mutants in mouse c127 cells by using focus formation assays. our primary conclusions are that all e1 mutants tested consistently gener ...19921333131
human papillomavirus type 16 expresses a variety of alternatively spliced mrnas putatively encoding the e2 protein.the full-length e2 protein of human papillomavirus type 16 is believed to act as a trans-repressor of the viral p97 promoter. previous reports have provided evidence that transcripts with the potential to encode the e2 protein contain the 880/2708 splice junction. we have further analyzed the structure of the e2-encoding transcripts. employing the rna polymerase chain reaction (pcr) technique and analyses of the rna pcr products by southern blot hybridization and dna sequencing, we revealed the ...19921333130
rolling-circle replication of a high-copy bpv-1 plasmid.we investigated the replicating form of a bovine papillomavirus type 1 (bpv-1) deletion mutant by direct electron-microscopic analysis of low molecular weight cellular dna fractions. the detection of viral plasmid dna replication intermediates was facilitated by the isolation of a spontaneously transformed mouse cell subclone containing an unusually high viral genome copy number (approx. 1000 per cell), and by employing a slight modification of the hirt fractionation procedure to reduce the leve ...19921333015
purification and characterization of epstein-barr virus gp340/220 produced by a bovine papillomavirus virus expression vector system.our initial results with a bovine papilloma virus (bpv) vector expression system indicated that we could produce significant amounts of epstein-barr virus (ebv) gp340/220 in the supernatant of a mouse fibroblast cell line. we have now extended these findings to show that the truncated version of gp340/220, where the membrane anchor sequence is deleted, is produced even after extended passage of the cells, at a level of approximately 1 mg/4 x 10(8) cells. a simple purification protocol using seph ...19921332270
glucocorticoid modulation of transformed cell proliferation is oncogene specific and correlates with effects on c-myc levels.in the presence of the glucocorticoid hormone dexamethasone, bovine papillomavirus-1 (bpv-1)-transformed c127 mouse fibroblasts assume a flattened morphology and reach a saturation density of only 50% of that attained without hormone. this phenotypic reversion of transformation is dependent on the continued presence of dexamethasone and occurs with concentrations as low as 1 nm. dexamethasone also suppresses the growth of the parental c127 cells as well as that of cells transformed by polyoma mi ...19921331773
a constitutive enhancer in the bovine papillomavirus upstream regulatory region shares genetic elements with the viral p1 promoter.the bovine papillomavirus upstream regulatory region represents a common element in the regulation of transcription from the five early viral promoters. we have determined the sequences required for transcription from the viral p1 promoter, which is located at the 5' end of the upstream regulatory region. in vitro transcription from p1 requires a 123-bp fragment (nucleotides 7153 to 7275; -33 to +90) consisting of an upstream tata-like sequence as well as an unidentified protein which binds to s ...19921331522
random-choice replication of extrachromosomal bovine papillomavirus (bpv) molecules in heterogeneous, clonally derived bpv-infected cell lines.using fluorescence in situ hybridization and southern blot analysis, we show that three clonally derived cell lines transformed with bovine papillomavirus (bpv), including id13, the cell line commonly employed for bpv replication studies, are heterogeneous populations having extensive cell-to-cell variation in both the distribution and amount of bpv dna. different subclones of id13 were found to differ in the form and amount of bpv dna they contain. most subclones showed no detectable bpv sequen ...19921331505
the induction of il-6 and gelatinase b by il-1 in mouse cell lines transformed with bovine papillomavirus: decreased production in tumorigenic cells.six cell lines, that were cloned from murine c127 cells infected by bovine papillomavirus type 1 (bpv1), were found to differ in the degree of transformation in vitro and of tumorigenicity in vivo. in these cell lines the degree of tumorigenicity was inversely correlated with il-6 induction by il-1 beta. whereas the parental c127 cell line produced 15-30 u/ml of il-6 spontaneously, none of the transformed cell lines produced significant levels of il-6 constitutively. on induction by human il-1 b ...19921330001
search for bovine papilloma virus dna in bovine ocular squamous cell carcinomas (boscc) and boscc-derived cell lines.although the cause of bovine ocular squamous cell carcinoma (boscc) is attributed to viruses in addition to cofactors (eg, uv light), to our knowledge, the final causative agent has not been described. bovine papilloma virus (bpv)-like particles were detected in approximately 33% of various putative precursor lesions of boscc. in contrast, it was reported that, using bpv-specific antibodies, it was not possible to detect viral antigens in boscc. fourteen established boscc and 9 boscc-derived cel ...19921329585
the spermicide nonoxynol-9 does not inactivate papillomavirus.vaginal spermicides are effective contraceptive, and are also capable of inactivating many sexually transmitted pathogens by their detergent effect on bacterial cell membranes and viral envelopes. a 5% concentration of nonoxynol-9, the most frequently used active ingredient of spermicides, was tested for its ability to reduce the transforming activity of bovine papillomavirus type 1 (bpv-1), and the infectivity of bk virus (bkv) and cytomegalovirus (cmv). nonoxynol-9 markedly reduced the infecti ...19921329236
crystal structure at 1.7 a of the bovine papillomavirus-1 e2 dna-binding domain bound to its dna target.the dominant transcriptional regulator of the papillomaviruses, e2, binds to its specific dna target through a previously unobserved dimeric antiparallel beta-barrel. the dna is severely but smoothly bent over the barrel by the interaction of successive major grooves with a pair of symmetrically disposed alpha-helices. the specific interface is an 'interwoven' network of interactions where the identifying base pairs of the target contact more than one amino-acid side chain and the discriminating ...19921328886
analysis by polymerase chain reaction of the physical state of human papillomavirus type 16 dna in cervical preneoplastic and neoplastic lesions.integration of human papillomavirus (hpv) dna into the host cell genome is believed to be essential for malignant progression. however unambiguous detection of the physical state of hpv is a difficult and time-consuming procedure. to resolve this issue a simple, rapid and highly sensitive technique of polymerase chain reaction (pcr) has been utilized for detecting the physical state of hpv-16 dna. investigations were carried out in 122 cervical specimens comprising the whole spectrum of cervical ...19921328489
evidence that the transcriptional trans-activating function of the bovine papillomavirus type 1 e2 gene is not required for viral dna amplification in division-arrested cells.amplification of bovine papillomavirus type 1 (bpv-1) dna in growth-arrested mouse cell cultures appears to mimic the process of induction of vegetative bpv-1 dna synthesis in cells of the stratum spinosum in productively infected bovine warts. in both cases, cells permissive for viral dna amplification express large amounts of viral e2 protein which accumulates within the cell nucleus. whereas in latently infected virus-transformed cells truncated transcriptional repressor forms of e2 predomina ...19921328476
replication of bovine papillomavirus vectors in murine cells.varying capacities for autonomous replication have been obtained with bovine papillomavirus type 1 (bpv-1)-based expression vectors in mouse c127 cells. both integration of the vector dna into the genome of the host cell and replication as monomeric extrachromosomal elements have been observed. in this study, we have examined what features of bpv-1 vectors influence their replication potential. transfection of the entire bpv-1 genome into c127 cells resulted in the replication of extrachromosoma ...19921327973
separation of the transcriptional activation and replication functions of the bovine papillomavirus-1 e2 protein.replication of bovine papillomavirus-1 (bpv-1) dna requires two viral gene products, the e1 protein and the full-length e2 protein. the 48 kda e2 protein is a site-specific dna-binding protein that binds to several sites which lie adjacent to the bpv-1 origin of replication. the 85 amino acid c-terminal domain contains the specific dna binding and dimerization properties of the protein. the approximately 200 amino acid n-terminal domain is crucial for transcriptional activation. both of these do ...19921327758
molecular cloning, analysis, and chromosomal localization of a mouse genomic sequence related to the human papillomavirus type 18 e5 region.the e5 open reading frame (orf) from bovine papillomavirus type 1 (bpv 1) as well as the e5 orfs from human papillomaviruses (hpv) type 6 and type 16 have been reported to transform immortalized rodent cells. in an analysis of murine and human tumors for the presence of putative papillomavirus-related sequences, we cloned amplified cellular sequences from the mouse cell line eb that cross-hybridized with the e5 orf of hpv 18. a 2.1-kb fragment termed hc1 was sequenced. in normal murine cells, it ...19921326990
mammalian and viral dna sequences which interfere with the maintenance of a centromeric vector in yeast.we constructed a recombinant plasmid by inserting into the prs314 yeast centromeric plasmid vector the mouse dna sequence responsible for the maintenance in transgenic mice of plasmid p12b1 (1). such constructs could constitute convenient shuttle vectors between yeast and mouse cells. however, the recombinant molecule could not be established as a stable plasmid in saccharomyces cerevisiae. a region with a limited similarity to the yeast centromere (cen element) is present in this mouse sequence ...19921326955
two cellular single-strand-specific dna-binding proteins interact with two regions of the bovine papillomavirus type 1 genome, including the origin of dna replication.we have identified and purified to near homogeneity two specific single-stranded dna-binding factors (spsf i and ii) with molecular masses of 42 and 39 kda, respectively, from calf thymus. gel retention analysis and competition experiments demonstrate that the ubiquitous proteins spsf i and ii specifically interact with single-stranded dna derived from the minimal in vitro origin of replication of bovine papillomavirus type 1 and a region of the viral genome proposed to be involved in plasmid ma ...19921326653
transient replication of human papillomavirus dnas.information on papillomavirus dna replication has primarily derived from studies with bovine papillomavirus type 1 (bpv-1). our knowledge of dna replication of the human papillomaviruses (hpvs) is quite limited, in part because of the lack of a cell culture system capable of supporting the stable replication of hpv dna. this study demonstrates that the full-length genomic dnas of hpv types 11 and 18 (hpv-11 and hpv-18), but not hpv-16, are able to replicate transiently after transfection into se ...19921326651
phylogenetic analysis of 48 papillomavirus types and 28 subtypes and variants: a showcase for the molecular evolution of dna viruses.papillomaviruses are attractive models for studying the molecular evolution of dna viruses because of the large number of isolates that exhibit genomic diversity and host species and tissue specificity. to examine their relationship, we selected two amino acid sequences, one of 52 residues within the early gene e1 and the other of 44 residues within the late gene l1, which allowed insertion- and deletion-free alignment of all accessible papillomavirus sequences. we constructed phylogenetic trees ...19921326639
synergism between bovine papillomavirus type 4 and the flavonoid quercetin in cell transformation in vitro.bovine papillomavirus type 4 (bpv-4) morphologically transforms primary bovine cells in vitro only in the presence of an activated ras gene. the transformed cells are capable of anchorage-independent growth, but are not immortal and are incapable of inducing tumors in nude mice, suggesting that other events are needed to convert the cells to the fully transformed phenotype. we show here that treatment of the cells with a single dose of the flavonoid quercetin leads to full oncogenic transformati ...19921325710
conserved cysteine residue in the dna-binding domain of the bovine papillomavirus type 1 e2 protein confers redox regulation of the dna-binding activity in vitro.the bovine papillomavirus type 1 e2 open reading frame encodes three proteins involved in viral dna replication and transcriptional regulation. these polypeptides share a carboxyl-terminal domain with a specific dna-binding activity; through this domain the e2 polypeptides form dimers. in this study, we demonstrate the inhibition of e2 dna binding in vitro by reagents that oxidize or otherwise chemically modify the free sulfhydryl groups of reactive cysteine residues. however, these reagents had ...19921323841
transcription of bpv-1 genes in transfected f9 cells.in f9 cells transformed with bovine papillomavirus type 1 (bpv-1) sequences two different phenotypes can be recognized. one cell type shows the characteristics of the parental stem cell line, whereas the other comprises cells with spindle-like morphology that do not adhere to each other, similar to retinoic acid-treated f9 embryonal carcinoma cells. the phenotypically altered cells plate more efficiently than the stem cells, grow well in soft agar and show an extended lifespan in the differentia ...19921323821
control of human papillomavirus type 11 origin of replication by the e2 family of transcription regulatory proteins.replication of human papillomavirus type 11 (hpv-11) dna requires the full-length viral e1 and e2 proteins (c.-m. chiang, m. ustav, a. stenlund, t. f. ho, t. r. broker, and l. t. chow, proc. natl. acad. sci. usa 89:5799-5803, 1992). using transient transfection of subgenomic hpv dna into hamster cho and human 293 cells, we have localized an origin of replication (ori) to an 80-bp segment in the upstream regulatory region spanning nucleotide 1. it overlaps the e6 promoter region and contains a sh ...19921323690
stable association between the bovine papillomavirus e5 transforming protein and activated platelet-derived growth factor receptor in transformed mouse cells.the 44-amino acid e5 transforming protein of bovine papillomavirus is the shortest protein known to induce tumorigenic transformation of fibroblasts. we showed previously that expression of the e5 protein activates the cellular beta receptor for platelet-derived growth factor (pdgf) and proposed that the activated receptor transmits the transforming signal to the cell. here we use coimmunoprecipitation analysis to show that the e5 protein and the activated pdgf receptor exist in a stable complex ...19921323117
multiple hpv infection: microanatomy by in situ hybridization and immunohistochemistry.specific human papillomavirus (hpv) types have been shown to be associated with proliferative epithelial lesions with variable biological consequences in infected patients. simultaneous infection by more than one hpv type has been infrequently reported, and its clinical significance is unknown. we have examined four biopsies of cervical and vulvar tissue, each with evidence of infection by two different hpvs. using both in situ hybridization and immunohistochemical techniques, we determined the ...19921323102
characterization of a stable eukaryotic cell line expressing the rous sarcoma virus integrase.the rous sarcoma virus integration protein (in) is required for efficient integration of viral dna into the host genome. in was expressed in mouse c127 cells using a bovine papillomavirus vector. this system utilizes the mouse metallothionein promoter and the sv40 late polyadenylation signal for efficient expression of in. a stable cell line derived from a single hygromycin-resistant colony was characterized. the expression of in increased significantly upon zn2+ induction of the metallothionein ...19921322585
effect of interferon gamma on the sensitivity of bovine-papilloma-virus(bpv1)-transformed cell lines to cell-mediated cytotoxicity.the effect of interferon gamma (ifn gamma) on the immunogenicity and immunosensitivity of mouse cell lines transformed by bovine papillomavirus type 1 (bpv1) dna was examined in a syngeneic mouse model. the overnight incubation of bpv1-transformed cell lines with 100 iu/ml ifn gamma did not affect their ability to induce the generation of cytotoxic effector cells but it clearly increased their sensitivity to lysis by interleukin-2-induced lymphokine-activated killer (lak) cells and by non-specif ...19921322243
viral e1 and e2 proteins support replication of homologous and heterologous papillomaviral origins.we have shown that e1 and e2 proteins of human papillomavirus type 11 (hpv-11) were essential to support the replication of the homologous viral origin (ori) in a transient replication assay, similar to reports on bovine papillomavirus type 1 (bpv-1). unexpectedly, matched or even mixed combinations of e1 and e2 proteins from hpv-11 or bpv-1 replicated either ori in human, monkey, and rodent cell lines of epithelial or fibroblastic lineage, albeit with varied efficiencies. either set of viral pr ...19921321423
identification and genetic definition of a bovine papillomavirus type 1 e7 protein and absence of a low-copy-number phenotype exhibited by e5, e6, or e7 viral mutants.the bovine papillomavirus type 1 (bpv-1) genome replicates as a multiple-copy plasmid in murine c127 cells transformed to neoplasia by virus infection or by transfection with bpv-1 dna. it was reported previously that bpv-1 genomes harboring frameshift mutations in the e6 or e7 open reading frame (orf) replicated in c127 cells transformed by these mutants at a low copy number. furthermore, the characterization of a bpv-1 mrna in which the e6 and e7 orfs were spliced together in frame has led to ...19921321280
papillomavirus associated skin lesions in a cat seropositive for feline immunodeficiency virus.a cat was presented with skin lesions consisting of slightly raised pigmented plaques, 2-7 mm in diameter with a rough slightly verrucous surface. histologically these lesions were identified as papillomas. a papillomavirus infection was demonstrated: virus-like particles were present in the nuclei of cells within the lesions, and staining with an anti-bovine papillomavirus (bpv-1) antibody was obtained. an infection with feline immunodeficiency virus was diagnosed in this cat; this condition ha ...19921320786
localization of bovine papillomavirus type 1 e5 protein to transformed basal keratinocytes and permissive differentiated cells in fibropapilloma tissue.we examined expression of the e5 transforming protein of bovine papillomavirus type 1 (bpv-1) in naturally and experimentally infected bovine cells. bovine conjunctival fibroblasts transformed in vitro by experimental infection with purified bpv-1 virions expressed significantly higher amounts of the 7-kda e5 protein than bpv-1-transformed murine c127 cells. indirect immunofluourescence analysis revealed a cytoplasmic, predominantly juxtanuclear, localization of e5 protein in the in vitro virus- ...19921319069
bovine papillomavirus type 1-transformed primary mouse fibroblasts show no correlation between tumorigenicity and viral gene expression, but c-myc gene expression is elevated in tumorigenic cell lines.bovine papillomavirus type 1 (bpv-1)-transformed primary mouse fibroblasts containing episomal or integrated bpv-1 sequences were analysed for virus-specific transcripts and c-myc gene expression. total bpv-1-specific expression was high in cell lines containing episomal bpv-1 dna in comparison to lines containing integrated bpv-1 sequences, mainly due to higher expression of the e6/e7 sequences. no correlation was found between the viral transcription and tumorigenicity, although bpv-1 gene exp ...19921318945
early promoters of genital and cutaneous human papillomaviruses are differentially regulated by the bovine papillomavirus type 1 e2 gene product.the physical state of the human papillomavirus (hpv) genome is usually different in malignant lesions of the skin, in which it is generally found in episomal form, and genital mucosa, in which it is frequently integrated with disruption of the e2 gene. using chimeric or natural hpv promoters in the presence of the bovine papillomavirus type 1 e2 gene product, we observed transcription activation or repression, depending on the distance of e2-binding motifs from the start site. we found a clear d ...19921318941
inhibition of bovine papillomavirus plasmid dna replication by adeno-associated virus.the helper-dependent human parvovirus adeno-associated virus type 2 (aav) inhibits both the oncogenic transforming abilities and the dna replication of its helper viruses, adenovirus (ad), and herpes simplex virus (hsv). as aav-2 also inhibits the transforming ability of bovine papillomavirus type 1 (bpv), aav-2 was assayed for its ability to inhibit bpv plasmid dna replication. here we find that the aav-2 rep78 gene is able to trans-inhibit bpv plasmid dna replication and that the aav-2 termina ...19921318608
vanadate enhances transformation of bovine papillomavirus dna-transfected c3h/10t1/2 cells.bovine papillomavirus (bpv) dna-transfected c3h/10t1/2 cells respond to tumor promoters by enhanced production of transformed foci. vanadate, a suspected carcinogen, is a mitogen, generates active oxygen species and alters phosphorylation of proteins. we investigated whether vanadate would enhance transformation of bpv dna-transfected c3h/10t1/2 cells. transformed foci in bpv dna transfected c3h/10t1/2 cells exposed continuously to vanadate for 21 days increased in a dose-dependent manner to 50- ...19921317748
mechanism of action of the papillomavirus e2 repressor: repression in the absence of dna binding.repression of papillomavirus e2-dependent gene expression was studied by using transient transfections into mouse embryo fibroblast cells. cotransfection of a gene corresponding to the naturally occurring repressor e2-tr along with the full-length e2 gene resulted in up to 98% repression of e2-dependent reporter gene expression. a series of e2 dna-binding domain mutants were transferred into the e2-tr form and characterized for their ability to repress e2-dependent transactivation. all mutants w ...19921316493
a new retrovirus packaging cell for gene transfer constructed from amplified long terminal repeat-free chimeric proviral genes.the retroviral gene transfer system is a powerful tool for somatic gene therapy. a retroviral stock with a high viral titer and lacking replication-competent virus (rcv) is desirable for this type of gene transfer. to fulfill these requirements, we made a new packaging cell line, designated ampli-gpe. to reduce the homology between proviral dna in the packaging cell and retroviral vector, the gag-pol and env genes of moloney murine leukemia virus were separated onto two different plasmids, pgp-k ...19921316479
reconstitution of an episomal mouse aprt gene as a consequence of recombination.when a functional murine adenine phosphoribosyltransferase (aprt) gene linked to bovine papilloma virus (bpv) dna is transfected into aprt- l cells, the cells are rendered aprt+ and the aprt gene persists as an episome. cotransfection with two bpv vectors, one containing the 5' half of the aprt gene and the other the 3' half of the gene, that share about 300 bp of common sequence in intron 2, produces aprt+ cells with functional aprt as an episome. southern blot analysis of low molecular weight ...19921313148
lack of immortalizing activity of a human papillomavirus type 16 variant dna with a mutation in the e2 gene isolated from normal human cervical keratinocytes.the oncogenic potential of a human papillomavirus type 16 (hpv16) variant cloned from normal human cervical keratinocytes has been tested in vitro using primary rodent epithelial cells and human cervical keratinocytes. the hpv16 variant was able to extend the lifespan of, but failed to immortalize, human keratinocytes. it could however cooperate with an activated ras oncogene to transform primary rodent cells. radioimmunoprecipitation assays of the rodent cells showed that they expressed the e7 ...19921312701
the bovine papillomavirus constitutive enhancer is essential for viral transformation, dna replication, and the maintenance of latency.bovine papillomavirus type 1 (bpv-1) has served as the prototype papillomavirus for the study of viral transcription, dna replication, and latency. however, no cis essential transcription control regions which are necessary for both transformation and replication of bpv-1 or any other papillomavirus have yet been defined. we have found that bpv-1 mutants with deletions in the long control region were defective for transformation and replication, with the essential region in the 5' long control r ...19921312634
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