| [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 ... | 1991 | 1652932 |
| 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 ... | 1991 | 1652950 |
| 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 ... | 1991 | 1653009 |
| 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 ... | 1991 | 1653173 |
| [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 ... | 1991 | 1653596 |
| 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 ... | 1991 | 1654378 |
| 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 ... | 1991 | 1654443 |
| 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 ... | 1991 | 1654923 |
| [comparison of vector properties of the usual and modified sequences of the bpv-1 genome]. | | 1991 | 1655372 |
| 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 ... | 1991 | 1655407 |
| the papillomavirus e2 regulatory proteins. | | 1991 | 1655748 |
| 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. | 1991 | 1655963 |
| 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 ... | 1991 | 1656065 |
| 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 ... | 1991 | 1656277 |
| 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 ... | 1991 | 1657721 |
| 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 ... | 1991 | 1658358 |
| 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 ... | 1991 | 1658398 |
| 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 ... | 1991 | 1658623 |
| 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 ... | 1991 | 1660837 |
| 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 ... | 1991 | 1661204 |
| 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 ... | 1991 | 1661371 |
| [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 ... | 1991 | 1661373 |
| 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 ... | 1991 | 1661672 |
| 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 ... | 1991 | 1662766 |
| 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 ... | 1991 | 1662803 |
| 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 ... | 1991 | 1662814 |
| 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 ... | 1991 | 1663110 |
| the papillomavirus e2 protein: a factor with many talents. | the products of the papillomavirus e2 open reading frame play a key role in the regulation of the viral cycle. e2 proteins can activate or repress viral promoters by several distinct mechanisms and viral dna replication requires the expression of the full-length e2 protein together with the product of the e1 open reading frame. this is an interesting example of how a single eukaryotic dna-binding protein has evolved to perform several different functions and it provides a valuable model system f ... | 1991 | 1663669 |
| structures of bovine and human papillomaviruses. analysis by cryoelectron microscopy and three-dimensional image reconstruction. | the structures of bovine papillomavirus type 1 (bpv-1) and human papillomavirus type 1 (hpv-1) were determined at 2.5 nm resolution by cryoelectron microscopy and three dimensional image reconstruction techniques. as expected, the reconstructions showed that both viruses consist of a t = 7 icosahedral capsid (approximately 60 nm in diameter) which surrounds a nucleohistone core. the capsid morphologies of the two viruses are nearly indistinguishable. each capsid consists of a shell layer (approx ... | 1991 | 1663794 |
| tumor progression in transgenic mice containing the bovine papillomavirus genome. | | 1991 | 1667568 |
| transcription factor e2 regulates bpv-1 dna replication in vitro by direct protein-protein interaction. | | 1991 | 1668086 |
| sequence-specific alkylation of dsdna with derivatives of pyrimidine oligonucleotides conjugated to 2-chloroethylamine groups. | reaction of homopyrimidine oligonucleotides bearing a 5'-terminal alkylating aromatic 2-chloroethyl-amino group with a bovine papilloma vector expressing human interferon-gamma was investigated. the oligonucleotide derivatives bound to corresponding homopurine-homopyrimidine sequences in dsdna and alkylated guanosine residues at these sites in the purine strand of the target. the alkylated dna can be cleaved at the modified residues. at ph 5.4, the reaction was highly specific to the target sequ ... | 1991 | 1668255 |
| generation of c127-derived cell lines expressing estrogen or progesterone receptors for studying gene regulation on bovine papilloma virus minichromosomes. | to study regulation of transcription by multiple steroid hormones we have stably introduced expression vectors for human estrogen and rabbit progesterone receptors into the genome of the murine fibroblast cell line c127. these cells express functional endogenous glucocorticoid receptor and support bovine papilloma virus minichromosomes, a useful system for studying the role of chromatin structure on gene expression. three clones containing progesterone receptor integrates and six containing estr ... | 1991 | 1668831 |
| diagnosis of nasopharyngeal carcinoma by means of recombinant epstein-barr virus proteins. | the immune response of patients with nasopharyngeal carcinoma to epstein-barr virus (ebv) antigens is diagnostic of the tumour. existing tests use ebv antigens produced in ebv-infected lymphoblastoid cells, but the virus replicates poorly in these cells. serum samples from 18 patients diagnosed as having nasopharyngeal carcinoma were screened by western blot analysis, enzyme-linked immunosorbent assay (elisa), and immunofluorescence tests for antibodies to the ebv-coded alkaline deoxyribonucleas ... | 1991 | 1672175 |
| the e5 oncoprotein of bovine papillomavirus binds to a 16 kd cellular protein. | the e5 oncoprotein of bovine papillomavirus type 1 is the smallest known viral transforming protein. it is a 44 amino acid polypeptide asymmetrically oriented in golgi and plasma membranes which appears to modify (either directly or indirectly) the internalization and phosphorylation of at least two growth factor receptors: egf and csf-1. to identify cellular proteins associated with e5, we have constructed two e5 fusion proteins, each of which contains a well-characterized epitope at the e5 ami ... | 1990 | 1688529 |
| a monoclonal antibody to ly-6 gene product inhibits generation of functionally active t cells and recognizes single antigenic specificity whose expression is up-regulated in virus-transformed rat fibroblast. | in order to elucidate the relationship between the structure and function of proteins encoded for by the ly-6 gene complex, a cdna was constructed for a ly-6.2 specificity and then monoclonal antibodies (mab) generated to bacterially synthesized protein. the addition of one of these mab, designated pb-19, inhibited the proliferative response of t cells to concanavalin a (con a) or major histocompatability complex (mhc) alloantigens. reactivity of pb-19 to the ly-6 specificity was blocked by a kn ... | 1990 | 1692303 |
| antibody-mediated neutralization in vivo of infectious papillomaviruses. | specific antibody-mediated neutralization of infectious human papillomavirus type 11 (hpv-11) was achieved in the athymic mouse xenograft system, in which hpv-11 induced morphological transformation of human foreskin. virus-specific neutralization was demonstrated by the ability of an hpv-11-specific polyclonal antiserum to neutralize hpv-11 infectivity and not bovine papillomavirus type 1 (bpv-1) or cottontail rabbit papillomavirus (crpv) infectivity. in all three virus infectivity systems, neu ... | 1990 | 1693698 |
| distribution and specific identification of papillomavirus major capsid protein epitopes by immunocytochemistry and epitope scanning of synthetic peptides. | monoclonal (mabs) and polyclonal antibodies were produced against the major capsid protein of detergent-disrupted, purified bovine papillomavirus type 1 (bpv-1). the precise locations of the corresponding epitopes were identified by the reactivity of mabs and selected polyclonal antibodies with synthetic, overlapping, hexameric peptides corresponding with 95% of the bpv-1 major capsid protein. the topography of these epitopes was determined by reactivity of antibodies with intact (conformational ... | 1990 | 1700026 |
| demonstration of evolutionary differences between conserved antigenic epitopes in the minor nucleocapsid protein of human papillomavirus types 6b, 16 and 18. | we studied human papillomavirus (hpv) minor nucleocapsid protein (l2) by epitope scanning. conserved antigenic epitopes identified by rabbit antiserum to bovine papillomavirus (bpv) were revealed in hpv-6b (amino acids, aa, 196-205); hpv-16 (aa:s 376-85) and hpv-18 (aa:s 221-230). l2 proteins. the first two epitopes were situated in hydrophilic regions of the proteins. aligning the aa-sequences that corresponded to the epitopes with the total l2 sequences of bpv and hpv1a revealed consensus moti ... | 1990 | 1700908 |
| enhancer activation by a single type of transcription factor shows cell type dependence. | promoter and enhancer elements contain multiple binding sites for ubiquitous and cell type-specific transcription factors which stimulate transcription synergistically. here we show that cell type-dependent enhancer activity can be achieved by mechanisms other than interactions between cell type-specific transcription factors and dna. the ability of the sv40 enhancer and the e2 transactivator from bovine papillomavirus (bpv-1) to stimulate transcription from a reporter gene with different minima ... | 1991 | 1714381 |
| comparison of neutralization of bpv-1 infection of c127 cells and bovine fetal skin xenografts. | bpv-1 induces focus formation in murine c127 cells and fibropapillomas in bovine fetal skin xenografts. in this study, we compared the specificity of neutralization of bpv-1 in both assay systems, using sera and monoclonal antibodies (mabs) selected to define neutralizing epitopes. sera from rabbits and cattle, inoculated with intact bpv-1 or pbv-2 virions, neutralize bpv-1 infectivity in both c127 cells and xenografts. selected human sera and murine mabs that react with intact bpv-1 particles, ... | 1991 | 1715330 |
| an element in the bovine papillomavirus late 3' untranslated region reduces polyadenylated cytoplasmic rna levels. | expression of the two bovine papillomavirus type 1 (bpv-1) late genes, l1 and l2, coding for the two capsid proteins, is limited to terminally differentiated keratinocytes in bovine fibropapillomas. this pattern of expression is determined both by the activity of the late promoter and by the inhibition of late region expression in less well differentiated cells. inhibition of l1 and l2 mrna production in nonpermissive cells must occur since the late region potentially could be transcribed from e ... | 1991 | 1717710 |
| identification of linear epitopes of the bpv-1 l1 protein recognized by sera of infected or immunized animals. | sera from cattle that had been inoculated with bpv-1 virions or with recombinant l1 proteins and serum from a rabbit that had been immunized with sds-denatured virions were evaluated for their reactivity with 466 overlapping synthetic peptides corresponding to 95% of the bpv-1 l1 protein. the late serological response of cattle to both intact virions and recombinant l1 proteins exhibited a similar profile of reactivity with approximately 70% (7 of 10) of l1 antigenic sites. however, the l1 serol ... | 1991 | 1718315 |
| antigenic and immunogenic epitopes shared by human papillomavirus type 16 and bovine, canine, and avian papillomaviruses. | all types of papillomaviruses (pv) share common, so-called group-specific epitopes. to identify the major group-specific epitopes, we immunized 26 guinea pigs or rabbits with purified bovine pv type 1 (bpv), canine pv, or avian pv from the common chaffinch. the resulting hyperimmune sera, as well as a commercially available rabbit antiserum to bpv and seven monoclonal antibodies to bpv, were tested in an enzyme-linked immunosorbent assay with a set of 66 overlapping 20-amino-acid peptides repres ... | 1991 | 1719234 |
| differentiation of parapoxviruses by application of orf virus-specific monoclonal antibodies against cell surface proteins. | monoclonal antibodies were produced against orf virus-specified cell surface proteins in an attempt to develop reagents capable of differentiating between members of the parapoxviridae. two immunization protocols were used to induce an anti-orf response in balb/c mice, one of which resulted in virus replication in the recipient. the monoclonal antibodies produced were tested for crossreactivity with bovine papular stomatitis virus (bps) and milker's node virus (mnv) by indirect immunofluorescenc ... | 1991 | 1719690 |
| the e5 oncoprotein target: a 16-kda channel-forming protein with diverse functions. | | 1991 | 1724370 |
| the central hydrophobic domain of the bovine papillomavirus e5 transforming protein can be functionally replaced by many hydrophobic amino acid sequences containing a glutamine. | the 44-amino-acid e5 transforming protein of bovine papillomavirus can induce growth transformation of cultured rodent fibroblast cell lines. previous studies revealed that efficient transformation of mouse c127 cells by the e5 protein required a central core of hydrophobic amino acids and several specific carboxyl-terminal amino acids. although a randomly derived sequence of hydrophobic amino acids could functionally replace the wild-type hydrophobic core, most such sequences could not. we show ... | 1992 | 1727496 |
| the 68-kilodalton e1 protein of bovine papillomavirus is a dna binding phosphoprotein which associates with the e2 transcriptional activator in vitro. | the e1 open reading frame of bovine papillomavirus type 1 encodes factors necessary for extrachromosomal maintenance of the viral genome in transformed cells. to facilitate biochemical characterization of the gene products encoded by this open reading frame, we have expressed the full-length e1 protein in a baculovirus-insect cell system. this protein was found to be phosphorylated and localized to the nucleus of infected cells. the e1 protein alone has affinity for dna but appears to lack speci ... | 1991 | 1846189 |
| characterization of the cis elements involved in basal and e2-transactivated expression of the bovine papillomavirus p2443 promoter. | transcriptional transactivation and repression by the viral e2 proteins are important regulatory mechanisms for the papillomaviruses. in the bovine papillomavirus type 1 (bpv-1), several viral promoters can be transactivated by e2 through e2-dependent enhancer elements located in the viral long control region (lcr), including promoters involved in e2 expression itself. this report demonstrates that the bpv-1 p2443 promoter is transactivated by e2-responsive elements in the lcr and that this prom ... | 1991 | 1846195 |
| homologous recombination in bovine papillomavirus shuttlevecter; effect of relative orientation of substrate sequences. | relative orientation of recombination substrates, neo gene, strongly influenced homologous recombination events in a bovine papillomavirus shuttle vector. between direct repeats, recombination occurred at a high frequency while between inverted repeats, it was rare. double strand break near the mutation site increased the recombination frequency between inverted repeats but not between direct repeats. formation of long heteroduplex as a recombination intermediate may explain this apparently para ... | 1991 | 1846540 |
| transient replication of bpv-1 requires two viral polypeptides encoded by the e1 and e2 open reading frames. | bovine papillomavirus (bpv) dna is maintained as an episome with a constant copy number in transformed cells and is stably inherited. to study bpv replication we have developed a transient replication assay based on a highly efficient electroporation procedure. using this assay we have determined that in the context of the viral genome two of the viral open reading frames, e1 and e2, are required for replication. furthermore we show that when produced from expression vectors in the absence of ot ... | 1991 | 1846806 |
| cooperative binding of the e2 protein of bovine papillomavirus to adjacent e2-responsive sequences. | the dna-binding properties of purified full-length e2 protein from bovine papillomavirus type 1 have been investigated by utilizing a quantitative gel shift analysis. by using a recombinant baculovirus which express the e2 open reading frame from the polyhedrin promoter, the full-length e2 protein was synthesized in insect cells and purified to homogeneity by using an e2 binding site (accgn4cggt)-specific oligonucleotide column. the kd of e2 binding to a 41-bp oligonucleotide containing a single ... | 1991 | 1848322 |
| transfection of lipoma cells with papilloma bovine virus subgenomic fragment. | lipoma cells with consistent chromosomal aberration have been transfected with plasmids carrying papilloma bovine virus subgenomic fragment (pbv 69). the successful transformation of the cells was ascerted on the changed growth pattern of the cells in liquid medium, colony formation in soft agar and modified cell appearance in electron microscopy; transfection with pbv 69 has not been, however, sufficient to immortalize lipoma cells. | 1991 | 1848483 |
| activation of the platelet-derived growth factor receptor by the bovine papillomavirus e5 transforming protein. | the bovine papillomavirus e5 gene encodes a 44 amino acid membrane-associated protein that can induce tumorigenic transformation of rodent fibroblast cell lines. genetic studies suggest that the e5 protein may transform cells by influencing the activity of cellular proteins involved in growth regulation. we report here that the endogenous cellular beta type receptor for the platelet-derived growth factor (pdgf) is constitutively activated in c127 and fr3t3 cells stably transformed by the e5 prot ... | 1991 | 1849073 |
| persistence of bovine papillomavirus (pbpv-1) as an extrachromosomal element in tissues of microinjected xenopus laevis. | | 1991 | 1849256 |
| histone hyperacetylation does not alter the positioning or stability of phased nucleosomes on the mouse mammary tumor virus long terminal repeat. | activation of mouse mammary tumor virus transcription by the hormone-bound glucocorticoid receptor results in disruption of a nucleosome that is specifically positioned on the promoter. limited treatment of cells with the histone deacetylase inhibitor sodium butyrate prevents receptor-dependent promoter activation and nucleosome disruption [bresnick, e. h., john, s., berard, d. s., lefebvre, p., & hager, g. l. (1990) proc. natl. acad. sci. u.s.a. 87, 3977-3981]. on the basis of this observation, ... | 1991 | 1849427 |
| the activation domain of the bovine papillomavirus e2 protein mediates association of dna-bound dimers to form dna loops. | the e2 transactivator protein of bovine papillomavirus binds its specific dna target sequence as a dimer. we have found that e2 dimers, preformed in solution independent of dna, exhibit substantial cooperativity of dna binding as detected by both nitrocellulose filter retention and footprint analysis techniques. if the binding sites are widely spaced, e2 forms stable dna loops visible by electron microscopy. when three widely separated binding sites reside on the dna, e2 condenses the molecule i ... | 1991 | 1849647 |
| the late region differentially regulates the in vitro transformation by cottontail rabbit papillomavirus dna in different cell types. | papilloma induced by the cottontail rabbit papillomavirus (crpv) progress at a high frequency to cancers. this property makes the crpv system unique to study the role of papillomaviruses in cancer development. in contrast to bovine papillomavirus type 1, no convenient in vitro transformation system for crpv has been available. here, we describe two in vitro systems that we have developed. transformation of nih 3t3 cells is greatly facilitated by deletions in the crpv late region. specifically, a ... | 1991 | 1849681 |
| positive and negative e2-independent regulatory elements in the long control region of bovine papillomavirus type 4. | the long control region (lcr) of bovine papilloma-virus type 4 demonstrated enhancer activity when cloned upstream of a bacterial chloramphenicol acetyltransferase reporter gene under thymidine kinase promoter control. deletion analysis of the lcr revealed the presence of several positive and negative control elements, all of which could function independently of the viral e2 trans-activator. each of the three positive elements present appeared to be paired with a negative element which modulate ... | 1991 | 1849970 |
| delay time for influenza virus hemagglutinin-induced membrane fusion depends on hemagglutinin surface density. | we have studied the kinetics of low-ph-induced fusion between erythrocyte membranes and membranes containing influenza virus hemagglutinin by using assays based on the fluorescence dequenching of the lipophilic dye octadecylrhodamine. stopped-flow mixing and fast data acquisition have been used to monitor the early stages of influenza virus fusion. we have compared this with the kinetics observed for fusion of an nih 3t3 cell line, transformed with bovine papillomavirus, which constitutively exp ... | 1991 | 1850019 |
| a region immediately adjacent to the origin of replication of bovine papilloma virus type 1 interacts in vitro with the nuclear matrix. | we have investigated the interaction of the 69% transforming fragment of the bovine papilloma virus type 1 (bpv1) with the nuclear matrix from 1361.5 cells (nih-3t3 cells transformed by a bpv chimeric construct). in vitro studies performed with end-labelled dna fragments and nuclear matrices prepared using a high-salt extraction procedure demonstrate the binding of a 672 bp fragment adjacent to the viral origin of replication and containing the plasmid maintenance sequence (pms-1). this fragment ... | 1991 | 1850268 |
| direct interaction between sp1 and the bpv enhancer e2 protein mediates synergistic activation of transcription. | the physical interaction of heterologous site-specific dna-binding proteins is an important theme in eukaryotic transcriptional regulation. in this paper, we show that the cellular transcription factor sp1 and the bpv-1 (bovine papillomavirus type 1) enhancer protein e2 activate transcription synergistically from two papilloma viral promoters and a series of synthetic promoter constructs in transient transfection experiments. furthermore, sp1 can target e2 to a promoter region even in the absenc ... | 1991 | 1850324 |
| transforming activity of bovine and human papillomaviruses in cultured cells. | | 1991 | 1851373 |
| malignant transformation of a papilloma induced by bovine papillomavirus type 4 in the nude mouse renal capsule. | a papillomatous cyst was induced by implanting bovine foetal palate epithelium, infected in vitro with bovine papillomavirus type 4 (bpv-4), beneath the renal capsule of a nude mouse. the benign tumour underwent malignant progression, developing into a squamous cell carcinoma with metastatic deposits in the spleen. the bovine origin of both the renal and splenic cancers was confirmed by the presence of bovine major histocompatibility complex class i antigens in the cancer cells and by sequencing ... | 1991 | 1851817 |
| characterization of bovine papillomavirus e1 region deletion mutants associated with neoplastic transformation in a murine cell line. | spontaneous focus formation in the contact-inhibited c127 cell line, cl.2, harbouring multiple copies of a bovine papillomavirus type 1 deletion mutant, was associated with the evolution of further viral genomic deletions in addition to an amplification of the viral genome copy number. three simple frameshift deletions of 308, 605 and 1291 bp, associated with separate transformation events, were mapped within the e1 open reading frame, implying a common mechanism of spontaneous transformation in ... | 1991 | 1851818 |
| the q300 gene: a novel transcription unit induced in simian virus 40-infected and -transformed mouse cells. | the q300 element is a single-copy 233-bp genomic mouse dna fragment carrying a high-affinity binding site for the simian virus 40 (sv40) large t antigen. this element was used to screen an embl3 mouse genomic library. we could identify a genomic clone containing an approximately 500-bp transcribed region flanking the q300 element. the transcribed region, termed the q300 transcription unit or q300 gene, is overexpressed in acutely sv40-infected or sv40-transformed mouse and rat cells. the q300 ge ... | 1991 | 1851876 |
| an e1m--e2c fusion protein encoded by human papillomavirus type 11 is asequence-specific transcription repressor. | we have isolated a putative, spliced e5 cdna of human papillomavirus type 11 (hpv-11) by polymerase chain reaction amplification of cdnas from an experimental condyloma. using retrovirus-mediated gene transfer, we isolated two novel hpv-11 cdnas, one of which had a splice linking nucleotides 1272 and 3377. this transcript also existed in experimental condylomata and in cervical carcinoma cells transfected with cloned genomic hpv-11 dnas. the 5' end of the transcript in transfected cells originat ... | 1991 | 1851879 |
| an interaction between the 5' flanking distal and proximal regulatory domains of the rat prolactin gene is required for transcriptional activation by estrogens. | in vitro studies have demonstrated that the estrogen receptor (er) can bind to the rat prl estrogen response element (ere) located 1700 basepairs upstream of the transcriptional start site. however, the mechanism by which the receptor-dna complex influences the activity of rna polymerase located in the promoter region is not understood. to begin investigating this process, we developed cell lines derived from gh3 cells that contain steroid-responsive bovine papillomavirus minichromosomes. within ... | 1990 | 1963474 |
| papillomavirus infection of aged persian cats. | papillomavirus infection was confirmed in 2 persian cats with sessile hyperkeratotic skin lesions. skin lesions were not typical papillomas as found in other species. papillomavirus were demonstrated in negative stain preparations of homogenized tissue and within nuclei of cells in the stratum granulosum. papillomavirus group-specific antigens were detected within nuclei corresponding to those containing virions. attempts to transmit this disease to other cats or propagate the virus in tissue cu ... | 1990 | 1965634 |
| bovine papillomavirus e2 repressor mutant displays a high-copy-number phenotype and enhanced transforming activity. | the methionine codon at bovine papillomavirus type 1 nucleotide 3091 was mutated to determine whether it may serve as an initiation codon for an e2 transcriptional repressor protein and to determine the role of the repressor in the biological activities of the virus. a series of transient expression experiments with cv1 cells documented that the mutation reduced expression of repressor activity from the viral genome and resulted in increased expression of the e5 transforming gene. viral genomes ... | 1990 | 2153255 |
| phenotypic analysis of bovine papillomavirus type 1 e2 repressor mutants. | the bovine papillomavirus type 1 (bpv-1) e2 open reading frame encodes three proteins: the e2 transcriptional transactivator, the e2 transcriptional repressor (e2-tr), and the e8/e2 fusion peptide. in this study, we describe the phenotypes of bpv-1 mutants which are disrupted in their capacity to encode either the e2 transcriptional repressor or the e8/e2 fusion peptide. we also describe experiments which demonstrate that the e8/e2 gene product functions similarly to e2-tr. in the context of the ... | 1990 | 2153256 |
| generation of cell-mediated cytotoxicity against bovine-papilloma-virus-transformed primary mouse cell lines. | the immunogenicity and immunosensitivity of primary mouse cell lines transformed by bovine papilloma virus 1 (bpv1) dna were studied in a syngeneic mouse model by determining cell-mediated cytotoxicity in the spleens of mice immunized with the transformed cells. one of the cell lines induced the generation of cell-line-specific thy1.2-positive cytotoxic effector cells. however, most of the cell lines tested induced the generation of thy1.2-positive effector cells, which in addition to bpv1-trans ... | 1990 | 2154331 |
| the dna-binding domain of hpv-16 e2 protein interaction with the viral enhancer: protein-induced dna bending and role of the nonconserved core sequence in binding site affinity. | we expressed the carboxy-terminal portion of the e2 open reading frame (orf)-encoded protein of human papillomavirus type 16 (hpv-16) and purified it to near homogeneity. using dnase i footprinting techniques, we show that like the homologous protein from bovine papillomavirus type 1 (bpv-1), hpv-18, hpv-11, it binds dna at the enhancer consensus motif accn6ggt. base and phosphate backbone contact points were determined using methylation protection and interference and ethylation interference as ... | 1990 | 2154890 |
| the e2 trans-activator can act as a repressor by interfering with a cellular transcription factor. | the e2 open reading frame (orf) of the bovine papillomavirus (bpv-1) encodes a family of site-specific dna-binding proteins. the full-length protein is a transcriptional activator, whereas the polypeptides that contain only the carboxy-terminal domain are repressors. here we show that the trans-activator can work as a repressor of transcription for one of the bpv-1 promoters by binding to a dna sequence required for basal activity of the promoter. this operator site is defined as a 12-bp sequenc ... | 1990 | 2155158 |
| sensitization of transformed rat cells to parvovirus mvmp is restricted to specific oncogenes. | the rat cell line fr3t3 was transformed with the retroviral oncogenes v-myc or v-src, with the dna tumor viruses sv40 or bovine papilloma virus strain 1 (bpv-1) or with the 69% transforming region of bpv-1. the transformants were compared with the uncloned parental line for their susceptibility to the lytic effect and to the replication of mvmp, an autonomous parvovirus. expression of v-myc and v-src proteins and of sv40 large t antigen correlated with a greater cell susceptibility to mvmp-induc ... | 1990 | 2157178 |
| serological responses to papillomavirus group-specific antigens in women with neoplasia of the cervix uteri. | certain types of human papillomaviruses have been linked to the development of carcinoma of the cervix uteri. we have analyzed 114 serum specimens from women with cervical intraepithelial neoplasia (cin) or carcinoma of the cervix uteri for the presence of serum antibodies against purified, disrupted bovine papillomavirus (bpv). the titers of immunoglobulin a (iga) antibodies against bpv were slightly elevated (p less than 0.025) in the sera from cin or cervical carcinoma patients compared with ... | 1990 | 2157738 |
| integrated hpv 1 genomes in a human keratinocyte cell line can be transactivated by a sv40/bpv1 recombinant virus which expresses bpv1 e2 proteins. | this paper describes studies carried out on an hpv 1 carrying human keratinocyte cell line (svd2) and two subclones of it. although these lines contain multiple copies of hpv 1 genomes, in situ hybridization revealed that integration was restricted to band q33 on the long arms of chromosome 2. an e4 1.25-kb mrna was specifically identified by northern blotting and a pcr generated cdna confirmed the presence of the e1/e4 spliced mrna which is abundant in hpv 1 containing papillomas. infection of ... | 1990 | 2158183 |
| mutational analysis of cis elements involved in e2 modulation of human papillomavirus type 16 p97 and type 18 p105 promoters. | cis-acting elements involved in e2 modulation of human papillomavirus type 16 (hpv-16) p97 promoter activity and hpv-18 p105 promoter activity were examined. in transfected primary human keratinocytes, each promoter had a basal activity that could be repressed by the bovine papillomavirus type 1 e2 gene product. mutational analysis of the e2-binding sites in the long control region upstream of each promoter revealed that e2 repression was mediated through the e2-binding sites proximal to each pr ... | 1990 | 2159546 |
| a bovine papillomavirus type-1 (bpv-1) containing plasmid replicates extrachromosomally in xenopus embryos. | | 1990 | 2159642 |
| tumorigenicity and h-2 expression of papillomavirus-transformed mouse cell lines. | tumorigenicity in immunocompetent syngeneic mice and h-2 class i antigen expression of bpv1-transformed mouse cell lines had no correlation. h-2 expression was examined using monoclonal anti-(h-2kb) and anti-(h-2db) antibodies in immunofluorescence staining for flow cytometry analysis and by determining the sensitivity of the cells to cytolysis by allostimulated spleen cells. nontumorigenic cell lines were as resistant as tumorigenic cell lines to natural killer activity. the results indicate th ... | 1990 | 2159847 |
| glucocorticoid receptor-dependent disruption of a specific nucleosome on the mouse mammary tumor virus promoter is prevented by sodium butyrate. | our laboratory has previously developed cell lines derived from mouse nih 3t3 fibroblasts and c127 mammary tumor cells that stably express mouse mammary tumor virus (mmtv) long terminal repeat fusion genes in bovine papillomavirus-based episomes. glucocorticoid hormone strongly activates transcription from episomes and induces the disruption of a single nucleosome in an array of phased nucleosomes on the mmtv promoter. sodium butyrate inhibits the glucocorticoid hormone-dependent development of ... | 1990 | 2160080 |
| transforming growth factor-beta expression in fibropapillomas induced by bovine papillomavirus type 1, in normal bovine skin, and in bpv-1-transformed cells. | there is substantial evidence to suggest that transforming growth factor-beta (tgf-beta) plays an important role in wound healing and tissue repair as well as in carcinogenesis. it has also been observed that naturally occurring bovine papillomavirus type 1 (bpv-1)-induced bovine fibropapillomas occur predominantly at traumatized sites of the body, suggesting that humoral factors released in wounds might be important for papillomavirus infection. we have therefore investigated the possible role ... | 1990 | 2160257 |
| evidence that replication initiates at only some of the potential origins in each oligomeric form of bovine papillomavirus type 1 dna. | in a subclone of id13 mouse fibroblasts latently infected with bovine papillomavirus type 1 (bpv-1) dna, the viral genome occurred as a mixture of extrachromosomal circular monomers and oligomers. multiple copies were also associated with the host cell genome, predominantly at a single site in a head-to-tail tandem array. we examined the replicative intermediates of extrachromosomal forms of bpv-1 dna by using two-dimensional gel electrophoresis. the results obtained indicate that initiation of ... | 1990 | 2160593 |
| transcriptional activation by the papillomavirus e6 zinc finger oncoprotein. | the introduction of the bovine (bpv) or human papillomavirus e6 gene into susceptible cells can result in their transformation, but there are few clues to the mechanism of action of the e6 gene. the characteristic features of e6 proteins are their small size (approximately 150 amino acids) and the potential to form two large zinc fingers. to determine if e6 can function as a transcription factor, the bpv e6 gene was fused to the sequence specific dna binding peptide encoded by the bpv e2 gene. t ... | 1990 | 2161335 |
| optimization of the hygromycin b resistance-conferring gene as a dominant selectable marker in mammalian cells. | the hyr gene, conferring resistance to hygromycin b (hy), has been modified for optimal expression in mammalian cells. modifications to the hyr gene and its expression cassette include: (1) removal of all upstream start codons, (2) conversion of the region around the start codon to the consensus sequence associated with efficient translation initiation, and (3) removal of downstream splice donor and acceptor sequences. the resulting hyr gene is an efficient dominant selectable marker that is use ... | 1990 | 2161383 |
| studies on vaccination against papillomaviruses: the immunity after infection and vaccination with bovine papillomaviruses of different types. | calves, free of antibodies to bovine papillomaviruses (bpv), were reared in isolation. one was infected with bpv-2, developed tumours and was resistant to homologous reinfection. groups of calves were infected with bpv-2, bpv-5 or bpv-6; they all developed and subsequently rejected type-specific tumours. they were then infected with bpv-4; they were not immune and oral papillomas were induced. groups of animals were vaccinated by intramuscular preparations of purified bpv-4 and bpv-6 and were ch ... | 1990 | 2161579 |
| studies on vaccination against papillomaviruses: a comparison of purified virus, tumour extract and transformed cells in prophylactic vaccination. | calves were vaccinated with two preparations made from one cutaneous fibropapilloma induced by bovine papillomavirus type 2 (bpv-2). one vaccine consisted of homogenised tumour; the other contained purified virus only. both produced resistance to a heavy challenge infection of bpv-2. one calf in the vaccinated group developed a small tumour and rejected it earlier than the control calves. it would appear likely that the prophylactic immune response was induced by viral structural proteins only a ... | 1990 | 2162579 |
| vaccinia recombinants expressing early bovine papilloma virus (bpv1) proteins: retardation of bpv1 tumour development. | papillomaviruses are aetiological agents of epithelial proliferative diseases in animals and in man. it was previously demonstrated that animals inoculated with live vaccinia recombinants expressing early proteins of polyoma virus resist challenge with polyoma-tumour cells, and this approach has been extended to the development of a vaccine against papillomavirus-transformed cells. bovine papillomavirus type 1 (bpv1), a virus responsible for dermal lesions in cattle, is a prototype virus of the ... | 1990 | 2163573 |
| histopathological development of equine cutaneous papillomas. | the histopathological development of equine cutaneous papillomas was studied in 78 warts naturally occurring in 50 one to 3-year-old thoroughbred or arab horses and in 54 warts experimentally induced in three 2-year-old thoroughbreds. lesions in the natural cases were categorized into three phases, growth, development and regression. main lesions of the growing phase were marked hyperplasia of the basal cells and mild to moderate acanthosis, hyper- and parakeratosis with a few intranuclear inclu ... | 1990 | 2164051 |
| the e2 transactivator of bovine papillomavirus type 1 is expressed from multiple promoters. | the e2 proteins of bovine papillomavirus type 1 (bpv-1) are a family of site-specific dna-binding proteins which regulate viral transcription by repression and activation. repressors e2-tr and e8/e2 are expressed from promoters p5 (p3080) and p3 (p890), respectively. previous reports have provided evidence that the transcript for the 48-kilodalton transactivator is initiated from a promoter proximal to the open reading frame encoding this protein (p2440 or p4). our studies extend these findings ... | 1990 | 2164604 |
| cooperative activation of transcription by bovine papillomavirus type 1 e2 can occur over a large distance. | the viral transcriptional factors encoded by the e2 open reading frame bind to the specific dna sequence elements accgnnnncggt, allowing activation or repression of transcription. we have analyzed bovine papillomavirus type 1 e2 transactivation using recombinant genes containing e2-binding sites inserted at either 3' or 5' positions relative to the heterologous transcriptional initiation site of the herpes simplex virus thymidine kinase gene. in these hybrid plasmids, strong transactivation requ ... | 1990 | 2164642 |
| the effect of retinoids, carotenoids and phenolics on chromosomal instability of bovine papillomavirus dna-carrying cells. | antioxidants were found to protect against the genotoxic effects of chemical and physical mutagenic and clastogenic agents. this study focused on the capacity of antioxidants to reduce an intrinsic and persistent chromosome instability. as a model system, strains of c127 cells, which were transformed by bovine papillomavirus (bpv) dna and which carry bpv dna varying from 20 to 160 copies, were used. transformed cells of 10 different strains showed a persistently high incidence of mitotic irregul ... | 1990 | 2165562 |
| implantation of genetically manipulated fibroblasts into mice as antitumor alpha-interferon therapy. | long-term parenteral administration of human alpha-interferon (huifn-alpha) is effective in the treatment of several malignancies, including chronic myelocytic leukemia. in the present study, a model for fibroblast-mediated huifn-alpha gene therapy for the treatment of chronic myelocytic leukemia is described. human ifn-alpha 5 complementary dna was inserted into a bovine papilloma virus plasmid vector (bmgneo) containing a neomycin resistance gene. the recombinant plasmid (bmgneo-ifn) was trans ... | 1990 | 2165855 |
| saturation mutagenesis using mixed oligonucleotides and m13 templates containing uracil. | | 1990 | 2166223 |
| human papillomavirus infection of the uterine cervix analyzed by nonisotopic in situ hybridization. | some types of human papillomaviruses (hpvs) have been suggested to be strongly related to uterine cervical carcinoma. an attempt to detect these in formalin-fixed, paraffin-embedded sections was made by either immunohistochemical or by in situ hybridization. anticapsid protein of bovine papillomavirus antibody labeled with peroxidase was used for immunohistochemistry, and biotin was used instead of radioisotopes to label probes for in situ hybridization, which resulted in low background and a ra ... | 1990 | 2167347 |
| papillomavirus trans-activator protein e2 activates expression from the promoter for the ribonucleotide reductase large subunit from herpes simplex virus type 2. | activation of the herpes simplex virus type 2 (hsv-2) large subunit of the ribonucleotide reductase (icp10) gene by papillomavirus dna encoding the e2 or e7 proteins was studied directly by immunofluorescence or by chloramphenicol acetyltransferase (cat) analysis with hybrid icp10 or ie175 and 38k promoter constructions. cotransfection with bovine papillomavirus type 1 or human papillomavirus type 16 (hpv-16) e2 dna enhanced cat expression from constructions in which cat is regulated by the icp1 ... | 1990 | 2167936 |
| identification of a 68-kilodalton nuclear atp-binding phosphoprotein encoded by bovine papillomavirus type 1. | e1 is the largest open reading frame (orf) of bovine papillomavirus type 1 (bpv-1) and is highly conserved among all papillomaviruses, maintaining its size, amino acid composition, and location in the viral genome with respect to other early genes. multiple viral replication functions have been mapped to the e1 orf of bpv-1, and evidence suggested that more than one protein was encoded by this orf. we previously identified a small protein (m) whose gene consists of two exons, one encoded by the ... | 1990 | 2168988 |
| topoisomerase ii-mediated dna damage of episomes in tumor-bearing mice. | observations of cells in culture have demonstrated that, for many antitumor agents, topoisomerase ii-mediated dna damage relates to cytotoxicity. however, there is no evidence in tumor-bearing animals to suggest that such agents induce topoisomerase ii-mediated damage of dna in solid tumors or that such damage reflects inhibition of tumor growth. to address this question, a mouse fibroblast cell line neoplastically transformed by an episomal element containing the v-ha-ras and bovine papillomavi ... | 1990 | 2169334 |
| therapeutic value of partial excision of lesions combined with administration of an autogenous vaccine during an episode of cutaneous papillomatosis in cattle of uganda. | the therapeutic value of partial excision of lesions combined with administration of an autogenous vaccine in calves during an episode of cutaneous papillomatosis was evaluated. of 10 holstein calves naturally infected with cutaneous papillomatosis, 5 were given 20 ml of autogenous vaccine in addition to undergoing partial excision of the lesions; the other 5 calves were not given vaccine. results indicate that partial excision combined with administration of autogenous vaccine has some therapeu ... | 1990 | 2170314 |
| a bovine papillomavirus constitutive enhancer is negatively regulated by the e2 repressor through competitive binding for a cellular factor. | the bovine papillomavirus type 1 long control region (lcr) contains dna sequence elements involved in the regulation of viral transcription and replication. differences in the levels of transcription have previously been noted between bovine papillomavirus type 1-infected rodent cell lines and bovine cells. to investigate these differences, fragments of the lcr were cloned into an enhancer-deleted chloramphenicol acetyltransferase expression vector and assayed for enhancer activity. a strong con ... | 1990 | 2170679 |