| reindeer papillomavirus transforming properties correlate with a highly conserved e5 region. | a papillomavirus was isolated from the epithelial layer of a cutaneous fibropapilloma on a swedish reindeer (rangifer tarandus). reindeer papillomavirus (rpv) is morphologically indistinguishable from other papillomaviruses, but the restriction enzyme cleavage pattern of its genome is different. no sequence homology was detected between rpv dna and the dnas of bovine papillomavirus type 1 (bpv-1) and avian papillomavirus when hybridization was performed under stringent conditions. however, the r ... | 1987 | 2822949 |
| proteins present in bovine papillomavirus particles. | analysis by two-dimensional gel electrophoresis and silver staining of heavy full, light full, and empty bovine papillomavirus particles has shown that the major capsid protein l1 is highly modified. besides exhibiting at least 13 isoelectric point variants of approximately the same molecular mass (54 kilodaltons), it is suggested that an additional heavier protein chain (69 kilodaltons) is also derived from l1 by glycosylation. these modifications may stabilize the particle structure. treatment ... | 1987 | 2822965 |
| stimulation of cellular dna synthesis by wild type and mutant bovine papillomavirus dna. | microinjection of recombinant plasmids containing bovine papillomavirus type 1 dna into the nuclei of mouse c127 cells results in the stimulation of cellular dna synthesis. mutations in the viral e2 gene have no apparent effect on this activity even though the same mutations prevent efficient c127 cell focus formation and inhibit transactivation by this gene. | 1987 | 2823817 |
| expression of human uterine tissue-type plasminogen activator in mouse cells using bpv vectors. | human tissue-type plasminogen activator (t-pa) cdna was cloned from uterine tissue and engineered in expression vectors for production in mouse c127 cells. the vectors consisted of the bovine papilloma virus-1 (bpv-1) genome and t-pa transcriptional unit with a mouse metallothionein (mt-1) promoter at the 5' end and mt-1 genomic sequences or sv40 early introns and polyadenylation signals at the 3' end. analysis of the expression vectors transfected into cells revealed that t-pa is expressed 100- ... | 1987 | 2824147 |
| the p39 promoter of minute virus of mice directs high levels of bovine growth hormone gene expression in the bovine papilloma virus shuttle vector. | the promoter of the capsid-coding genes of the autonomous parvovirus minute virus of mice (mvm) is shown to drive high levels of expression of the heterologous bovine growth hormone (bgh) gene in a bovine papilloma virus (bpv)-based shuttle vector. the expression of bgh directed by the mvm p39 promoter was, on average, higher than that obtained from the widely used metallothionein promoter. these results indicate that the mvm-p39/bpv shuttle vector will be generally useful for the high-level exp ... | 1987 | 2824293 |
| human cytomegalovirus (hcmv) enhances bovine papilloma virus (bpv) transformation in vitro. | infection of nih 3t3 cells with a combination of hcmv and bpv resulted in more foci than infection with bpv alone. foci were microscopically apparent at 4 days in the mixed infection and did not appear until 2 days later in the cultures infected with bpv alone. the enhancement was abolished by heat inactivation of the hcmv and also when the hcmv was replaced by a "mock inoculum." southern blot analysis of cellular dna from transformed cells showed a similar amount of extrachromosomal bpv dna in ... | 1987 | 2824682 |
| mutational analysis of the 3' open reading frames and the splice junction at nucleotide 3225 of bovine papillomavirus type 1. | functional analysis of the 3' open reading frames (orfs) of bovine papillomavirus type 1 (bpv-1) has been complicated by the organization of that part of the genome. a region between nucleotides (nt) 3173 and 3551 contains three overlapping orfs (e2, e3, and e4), as well as a 3' splice junction at nt 3225 which is used by many of the bpv-1 transcripts. to more clearly assign functions to specific orfs in this region, single-base substitution mutations were generated which introduced translationa ... | 1987 | 2824822 |
| cloning and characterization of a papillomavirus associated with papillomas and carcinomas in the european harvest mouse (micromys minutus). | individuals in a colony of european harvest mice (micromys minutus) were diagnosed with a variety of skin tumors including papillomas, trichoepitheliomas, and sebaceous carcinomas. papillomavirus group-specific antigens and viruslike particles were detected in the papillomas. a 7.6-kilobase supercoiled circular dna, which was cleaved once by ecori, was visualized in papilloma extracts by low-stringency southern blot hybridization with a bovine papillomavirus type 2 probe. the molecule was cloned ... | 1988 | 2824849 |
| messenger rnas from the e1 region of bovine papillomavirus type 1 detected in virus-infected bovine cells. | bovine papillomavirus type 1 dna replicated to a high copy number in virus-infected bovine fibroblasts. infected bovine cells were therefore used as a source of rna for northern blotting analysis to search for viral transcripts hybridizing to the e1 gene region, implicated in viral dna replication. cytoplasmic polyadenylated rna preparations contained at least five different e1-region transcripts, ranging from 1200 to approximately 4500 nucleotides in length. all of these species contained seque ... | 1987 | 2825116 |
| replication of plasmids derived from bovine papilloma virus type 1 and epstein-barr virus in cells in culture. | the major components encoded by bpv-1 and ebv that act in plasmid replication of these viral dnas in latently infected cells are now known. the minimal dna sequences required in cis have been delineated, and the genes whose products are required in trans have been identified. the only required trans-acting gene of ebv, ebna-1, has been shown to bind specifically to the cis-acting element, orip. the current advanced understanding of plasmid replication of mtdna and sv40 dna is likely to aid in th ... | 1987 | 2825737 |
| papillomas and cancer in cattle. | papillomaviruses induce hyperproliferation of epithelial cells of the skin or mucosa (papillomas), and certain types can also infect fibroblasts. they are a very heterogeneous group of viruses, and individual types are associated with specific lesions. the papillomas are mostly benign but some tumours may eventually undergo malignant conversion when genetic or environmental factors are involved. in cattle, bovine papillomavirus type 4 (bpv-4) is the causative agent of papillomas of the alimentar ... | 1987 | 2825987 |
| cis activation of the c-myc gene in bovine papilloma virus type 1/human c-myc hybrid plasmids. | the c-myc gene amplification observed in human tumors is likely to represent an activation mechanism aiming at an increased transcription level. in order to evaluate the biological significance of this amplification in the malignant transformation we have designed an experimental model that could possibly mimic this situation in vitro. we have constructed a series of plasmids which physically link the human c-myc gene to the bovine papilloma virus type 1 genome (bpv1) and therefore should be mai ... | 1988 | 2826197 |
| detection of dna of human papillomavirus types 6/11 and 16/18 in cell scrapings of the uterine cervix by filter in situ hybridisation. correlation with cytology, colposcopy and histology. | the application of filter in situ hybridisation (fish) to detect the presence of the dna of human papillomavirus genotypes 6/11 and/or 16/18 in cell scrapings of the uterine cervix of 248 women in western australia is described. the results obtained by fish are related to cervical dysplasia as assessed by cytology, colposcopy and histology. the detection of hpv infection was more sensitive and specific by fish than by either histological/cytological evidence of an hpv cytopathic effect (koilocyt ... | 1987 | 2826222 |
| identification of the human papillomavirus e2 protein in genital tract tissues. | a 27-kilodalton protein representing approximately 60% of the e2 open reading frame of human papillomavirus type 6 (hpv-6) was synthesized in a bacterial expression system. affinity-purified polyclonal antibody to this protein detected the probable e2 gene product as a 50-kilodalton protein in most condylomas by western blot (immunoblot) analysis. the e2-positive condylomas were associated with hpv-6, hpv-11, hpv-16, or unidentified hpvs. | 1988 | 2826817 |
| multiple cis-active elements in the long control region of bovine papillomavirus type 1 (bpv-1). | a 1.0 kb region of the bpv-1 genome (the long control region, lcr), contains controls for transcription and the origin of replication. transcription directed by the lcr is activated by the viral encoded e2 protein. to define the essential cis acting elements that are required to control transcription we have constructed a series of deletions throughout the lcr. we have identified three important domains in the lcr, two of which respond to e2. we have analysed the ability of small subcloned regio ... | 1987 | 2827118 |
| the bpv1-e2 trans-acting protein can be either an activator or a repressor of the hpv18 regulatory region. | the human papillomavirus 18 (hpv 18) long control region contains promoter and enhancer elements whose activity is restricted to several human cell lines of epithelial origin. this enhancer possesses a considerable constitutive activity which is further stimulated in the presence of the e2 trans-activating protein of bovine papillomavirus 1 (bpv1). surprisingly the same bpv1 protein strongly repressed transcription from the genuine hpv18 enhancer-promoter dna sequences. we suggest that binding o ... | 1987 | 2828029 |
| vaccines for latent viruses. | there are two traditional ways to modify a virus for immunization: (1) kill the virus or (2) use a live, attenuated virus. there are three modern ways to prepare vaccines: (1) extract and purify a part of the virus that is immunogenic, (2) synthesize a polypeptide immunogen piece of the virus, or (3) use recombinant deoxyribonucleic acid or gene splicing to prepare an immunogenic portion of the virus. the last three produce subunit vaccines that can be made to contain no deoxyribonucleic acid. t ... | 1988 | 2828442 |
| papillomavirus in the vapor of carbon dioxide laser-treated verrucae. | vapor produced by the carbon dioxide laser during the vaporization of papillomavirus-infected verrucae was analyzed for viral dna content. two models were used for evaluation: an in vitro cutaneous bovine fibropapilloma and an in vivo human verruca model. four bovine fibropapillomas were exposed to various laser parameters with power densities of 38,200 to 130 w/cm2 and energy fluences of 3820 to 130 j/cm2. the generated vapor was collected in a chamber in line with a vacuum system. hybridizatio ... | 1988 | 2828703 |
| structure and genetic expression of papillomaviruses. | this article reviews the physical structures, genetic organization, expression, and regulation of papillomaviruses. in view of the extensive characterization of cellular transformation and viral functions that have been achieved in experimentally infected animals and in transformed cell cultures, the bovine papillomavirus type 1 (bpv-1) and shope cottontail rabbit papillomavirus (crpv) are compared and contrasted with the human papillomaviruses. | 1987 | 2829072 |
| hepatitis b virus suppresses expression of human beta-interferon. | to determine whether hepatitis b virus (hbv) regulates the expression of the human beta-interferon gene, a series of recombinant bovine papilloma virus plasmids containing the human interferon gene and various fragments of the hbv genome were constructed and used to transform c127 cells, a murine fibroblast line. analysis of the dna from transformed c127 cells indicated that the interferon gene was intact and that the plasmids replicated as stable multicopy elements. the 1828-base-pair bamhi hbv ... | 1988 | 2829171 |
| integration and transcription of human papillomavirus type 6 recombinant dna in mouse cells. | human papillomavirus (hpv) dna is found in nature mostly in an episomal form. however, in permanent cell lines established from cervical carcinomas in which hpv sequences are present, they are usually integrated in the host genome. in vitro studies of hpv have been hampered because of the difficulty of stably maintaining hpv sequences in transfected cells. we have cloned the entire hpv6 genome into three vectors: pml2, a derivative of pbr322 lacking the "poison sequences"; p142-6, a plasmid cont ... | 1987 | 2829459 |
| the bovine papillomavirus genome and its uses as a eukaryotic vector. | | 1987 | 2829815 |
| secretion of soluble functional insulin receptors by transfected nih3t3 cells. | in order to determine whether the human insulin receptor ectodomain can be expressed as a functional protein, the coding regions for the transmembrane and cytoplasmic domain of a full-length human insulin receptor cdna were deleted by site-directed mutagenesis, and the resultant construct was inserted into a bovine papilloma virus vector under the control of the mouse metallothionein promoter. after transfection of mouse nih3t3 cells, a cell line secreting an insulin binding protein was isolated ... | 1988 | 2830271 |
| cis-acting negative control of dna replication in eukaryotic cells. | we show that in stable monkey cell lines, the replication of a chimeric sv40-bpv episomal replicon occurs once and only once per cell cycle. the copy number of this episome is stably maintained even when an excess of the limiting initiation factor t antigen is provided. these experiments therefore uncover a cis-acting negative control mechanism whereby replication control is not focused on limiting the activity of positive factors; rather, replication is permitted in unreplicated replicons but i ... | 1988 | 2830984 |
| establishment of mouse cell lines which constitutively secrete large quantities of interleukin 2, 3, 4 or 5, using modified cdna expression vectors. | mouse cell lines of different lineages have been established which constitutively secrete large quantities of recombinant mouse interleukins (mil2, mil3, mil4 or mil5). an existing bovine papilloma virus-based expression vector, pbv-1mtha, was modified to allow transformed x63ag8-653 myeloma cells, nih 3t3 fibroblasts and c127 mammary tumor cells to stably carry multiple copies of the vector, to express the inserted cdna encoding a single interleukin constitutively, and to secrete the interleuki ... | 1988 | 2831066 |
| dna bending is induced in an enhancer by the dna-binding domain of the bovine papillomavirus e2 protein. | the e2 gene of bovine papillomavirus type 1 has been shown to encode a dna-binding protein and to trans-activate the viral enhancer. we have localized the dna-binding domain of the e2 protein to the carboxyl-terminal 126 amino acids of the e2 open reading frame. the dna-binding domain has been expressed in escherichia coli and partially purified. gel retardation and dnase i "footprinting" on the bovine papillomavirus type 1 enhancer identify the sequence motif accn6ggt (in which n = any nucleoti ... | 1988 | 2831538 |
| dna sequence of the hpv-16 e5 orf and the structural conservation of its encoded protein. | infection of cervical epithelium by human papillomavirus type 16 (hpv-16) appears to be closely associated with the development of cervical dysplasia and carcinoma. by inference from genetic and biochemical studies of the bovine papillomavirus, the e5 orf of the human papillomaviruses is anticipated to encode a "transforming" protein. in an effort to compare the e5 orf of hpv-16 with other human papillomaviruses and bovine papillomavirus, we sequenced this region from a new isolate of hpv-16 whi ... | 1988 | 2831662 |
| calmodulin is involved in regulation of cell proliferation. | a chicken calmodulin (cam) gene has been expressed in mouse c127 cells using a bovine papilloma virus (bpv)-based vector (bpv-cm). the vector-borne genes produce a mature mrna of the expected size that is present on cytoplasmic polyribosomes. in clonal cell lines transformed by bpv-cm, expression of the cam gene produced cam levels 2- to 4-fold above those observed in cells transformed by bpv alone. increased intracellular cam caused a reduction of cell cycle length that is solely due to a reduc ... | 1987 | 2832147 |
| cross-hybridization and relationships of various papillomavirus dnas at different degrees of stringency. | cloned dnas of 21 different papillomaviruses which naturally infect mammals and one bird papillomavirus were compared for relative homology by southern blot hybridization. blots were carried out under low (tm-40 degrees), medium (tm-33 degrees), and high (tm-22 degrees) stringency conditions. at higher stringency, human papillomaviruses cross-hybridized with each other reflecting species-specific similarities. bovine papillomavirus types 1, 2, 5, european elk papillomavirus, and deer papillomavi ... | 1987 | 2832347 |
| functional mapping of the human papillomavirus type 11 transcriptional enhancer and its interaction with the trans-acting e2 proteins. | the transcriptional enhancer sequences of the papillomaviruses are regulated by trans-acting factors encoded by the viral e2 open reading frame. we have performed detailed functional and physical analyses of the enhancer of the human papillomavirus type 11 (hpv-11). using the chloramphenicol acetyltransferase (cat) assay in transiently transfected monkey cv-1 cells, the enhancer region has been localized to a 270-bp tract immediately preceding the e6 open reading frame, and it consists of two fu ... | 1988 | 2833426 |
| study of the e2 gene product of the cottontail rabbit papillomavirus reveals a common mechanism of transactivation among papillomaviruses. | the long control region (lcr) of the cottontail rabbit papillomavirus (crpv) harbors a transcriptional promoter which can be transactivated, as reflected by cat gene expression, by cotransfection with plasmids which express the intact e2 open reading frame of crpv, human papillomavirus type 18 (hpv18), and bovine papillomavirus type 1 (bpv1). the e2 protein of crpv can also transactivate the lcrs of bpv1, hpv1, and hpv18 inserted in front of the cat gene in enhancer or promoter configuration. co ... | 1988 | 2833608 |
| [new technology of vaccine production--international prospect of the development--subunit vaccine obtained by genetic engineering. b. genetic engineering method using animal cells]. | | 1987 | 2834577 |
| "hit and run" transformation of mouse c127 cells by bovine papillomavirus type 4: the viral dna is required for the initiation but not for maintenance of the transformed phenotype. | morphological transformation of c127 mouse fibroblasts by bovine papillomavirus type 4 (bpv-4) dna depends on additional factors, including cell density, the presence of tpa, the concentration of fetal calf serum, and the physical state of the input dna. low cell density or the presence of tpa allows the achievement of full transformation, suggesting that disturbance of cell-to-cell contact may be necessary for the expression of the malignant phenotype. tpa also induces a burst of viral dna synt ... | 1988 | 2834874 |
| the specific dna recognition sequence of the bovine papillomavirus e2 protein is an e2-dependent enhancer. | the upstream regulatory region (urr) of the bovine papillomavirus (bpv) genome contains an enhancer that is activated by a bpv e2 gene product. we have previously found that a bacterially derived e2 fusion protein specifically interacted with several fragments of urr dna, suggesting that e2 may activate transcription by directly binding to the enhancer. each of the bound fragments contains at least one copy of a conserved motif (accn6ggt). to determine if this motif is required and sufficient fo ... | 1988 | 2835231 |
| the carboxy-terminal domain shared by the bovine papillomavirus e2 transactivator and repressor proteins contains a specific dna binding activity. | the e2 open reading frame of bovine papilloma virus 1 (bpv-1) has been shown to encode both positive and negative acting transcriptional regulatory factors. the dna binding properties of these factors were analysed to investigate the mechanism by which they might regulate viral gene expression. polypeptides corresponding to the full-length e2 product and a shorter protein thought to represent the repressor function were synthesized in vitro by translation of t7 polymerase generated transcripts. ... | 1988 | 2835232 |
| interaction of the bovine papillomavirus type 1 e2 transcriptional control protein with the viral enhancer: purification of the dna-binding domain and analysis of its contact points with dna. | the e2 gene of bovine papillomavirus type 1 positively and negatively regulates the transcriptional enhancer located in the long control region of the viral genome. the dna-binding domain of the e2 gene product was suspected to interact with the dna sequence motif accn6ggt. we have shown that the carboxy-terminal 126 amino acids of the e2 protein constitute the dna-binding domain. in this paper we described the expression of the e2 carboxy terminus in escherichia coli and its subsequent purifica ... | 1988 | 2835497 |
| the product of the bovine papillomavirus type 1 modulator gene (m) is a phosphoprotein. | the m gene of bovine papillomavirus type 1 has been genetically defined as encoding a trans-acting product which negatively regulates bovine papillomavirus type 1 replication and is important for establishment of stable plasmids in transformed cells. the gene for this regulatory protein has been mapped in part to the 5' portion of the largest open reading frame (e1) in the virus. we constructed a trpe-e1 fusion gene and expressed this gene in escherichia coli. rabbits were immunized with purifie ... | 1988 | 2836626 |
| the e5 gene of bovine papillomavirus type 1 is sufficient for complete oncogenic transformation of mouse fibroblasts. | the transforming 69% fragment of the bovine papillomavirus type-1 genome was inserted into a retrovirus vector, which also expresses g418 resistance, and the resulting construct was used for transfection of psi 2 cells. c127 cells infected with virus-containing medium from g418 resistant psi 2 clones were selected for g418 resistance and/or transformation. g418 resistant cells contained invariably a 4.4 kb provirus. the transformed cells, in contrast, contained either a 2.8 kb or a 5.4 kb provir ... | 1988 | 2836779 |
| expression of the e2 open reading frame of papillomaviruses bpv1 and hpv6b in silkworm by a baculovirus vector. | to produce and characterize the nature of the e2 protein of papillomaviruses, we have developed a system to express the dna sequence containing an open reading frame (orf) as a fusion protein in cultured insect cells and silkworms. the dna fragments of the e2 orf predicted from the dna sequence of bovine papillomavirus type 1 and human papillomavirus type 6b were linked to the n-terminal part of polyhedrin gene of the baculovirus bombyx mori nuclear polyhedrosis virus (bmnpv) vector. hybrid prot ... | 1988 | 2837019 |
| trans-activation of class ii (i-a alpha) gene by i-a beta gene transfection using bovine papilloma virus as a shuttle vector system. | we have engineered a bovine papilloma virus to carry the class ii mhc (a beta d) gene. the recombinant plasmid was introduced into various mouse b cell hybridomas by co-transfecting with the neomycin-resistance gene. several transfectants which received only the beta-chain gene of i-ad, expressed i-ad proteins on the cell surface. their presence was determined by direct immunofluorescence and by northern blot hybridization as well as rna dot blot hybridization. these i-ad molecules could induce ... | 1988 | 2837510 |
| immunohistochemical identification of human papillomavirus infection in tissues from cervical precancerous and early cancerous lesions among indian women. | paraffin sections of 50 cervical condyloma biopsies from patients with precancerous and early cancerous lesions of the uterine cervix were screened for human papillomavirus (hpv) antigen by peroxidase-antiperoxidase (pap) staining using genus specific anti-bovine papillomavirus serum (rabbit). the intra-nuclear hpv positivity was observed in 20 percent (10/50) of biopsies studied. further, proportionately larger number of cases with moderate dysplasia (cin ii) associated with koilocytotic change ... | 1988 | 2837927 |
| analysis of the l1 gene product of human papillomavirus type 16 by expression in a vaccinia virus recombinant. | the l1 open reading frame of human papillomavirus type 16 (hpv16) has been expressed in vaccinia virus under the control of both the 7.5k early and late promoter, and the 4b major late promoter. antibodies to a beta-galactosidase fusion protein containing a c-terminal portion of the hpv16 l1 gene product were used to compare the levels of l1 expression in the two recombinants, and showed that greater levels of expression were obtained when the gene was placed under the control of the 4b late pro ... | 1988 | 2838573 |
| functional analysis of the individual enhancer core sequences of polyomavirus: cell-specific uncoupling of dna replication from transcription. | polyomavirus (py) enhancer core elements were compared for their ability to activate py early transcription and dna replication in mouse 3t6 cells, lymphoid cell lines, and undifferentiated embryonal carcinoma cells. by examining the pattern of genetic change in a number of cell-specific py variants, we identified subenhancer sequences that may be functionally important for virus replication. four such distinct enhancer consensus sequences were synthesized and designated as the a core (homologou ... | 1988 | 2838739 |
| phenotypic transformation of primary mouse fibroblasts by bpv 1 dna. | cultures of primary fibroblasts of c57bl/6j mice were used as targets for transformation by bovine papillomavirus type 1 (bpv 1) dna. although no foci were observed, several lines of transformed cells were established by subculturing. these immortalized cell lines had in vitro growth characteristics in high and low serum media and saturation densities typical of transformed cells. karyotype analyses revealed extensive aneuploidic changes. in two of the three cell lines analyzed, viral dna was pr ... | 1988 | 2839131 |
| effect of retinoic acid on bovine papillomavirus (bpv) dna-induced transformation and number of bpv dna copies. | the effect of all-trans-retinoic acid (ra) was examined on (1) transformation induced in c127 cells by transfection with plasmid pdbpv-1 (142-6), which contains dna of bovine papillomavirus (bpv), (2) the capacity of transformed bpv dna-containing clones to form colonies with transformed properties (e.g., piling up into multilayered colonies), and (3) the number of bpv dna copies in transformed cells. at nontoxic doses ranging from 10(-7) to 10(-5) m, ra reduced the frequency of transformed foci ... | 1988 | 2839430 |
| promoters of bovine papillomavirus type 1: in vitro activity and utilization. | five of six bovine papillomavirus type 1 (bpv-1) promoters which were previously mapped by determining the 5' termini of viral mrnas from bovine fibropapillomas and bpv-1-transformed cells were found to be active under in vitro transcription conditions. transcription initiation at each of these promoters was accurate at the nucleotide level as determined by primer extension analysis. the most active promoter in vitro was p89, a typical rna polymerase ii promoter with both tata and caat boxes. th ... | 1988 | 2839684 |
| regulation of human papillomavirus type 11 enhancer and e6 promoter by activating and repressing proteins from the e2 open reading frame: functional and biochemical studies. | e2-c, a protein consisting mainly of the carboxy-terminal 45% of the human papillomavirus type 11 (hpv-11) e2 protein, was expressed from the rous sarcoma virus long terminal repeat in mammalian cells. it competitively repressed the stimulatory action of the full-length e2 protein on the hpv-11 enhancer located in the upstream regulatory region, as assayed by the expression of a reporter gene from the simian virus 40 (sv40) early promoter in transiently transfected monkey cv-1 cells. a mutation ... | 1988 | 2839716 |
| site-specific dna recombination in mammalian cells by the cre recombinase of bacteriophage p1. | the cre protein encoded by the coliphage p1 is a 38-kda protein that efficiently promotes both intra- and intermolecular synapsis and recombination of dna both in escherichia coli and in vitro. recombination occurs at a specific site, called lox, and does not require any other protein factors. the cre protein is shown here also to be able to cause synapsis of dna and site-specific recombination in a mammalian cell line. a stable mouse cell line was established that expresses the cre protein unde ... | 1988 | 2839833 |
| activation of t cell-derived lymphokine genes in t cells and fibroblasts: effects of human t cell leukemia virus type i p40x protein and bovine papilloma virus encoded e2 protein. | the effects of p40x, a product of an human t cell leukemia virus type i, on the activation of lymphokine genes were examined. the mouse gm-csf and il-3 genes were activated by cotransfection with a px containing plasmid both in jurkat and cv1 cells. mouse gm-csf gene was also activated by phytohaemagglutinin a (pha)/phorbol myristate acetate (pma) or pma/calcium ionophore a23187 stimulation. the 5'-flanking region of the mouse gm-csf gene which is required for activation by px or mitogen was map ... | 1988 | 2840644 |
| bovine papillomavirus mutant temperature sensitive for transformation, replication and transactivation. | the genetic analysis of the papillomaviruses has been hampered by the lack of mutants conditionally defective for viral biological activities. we report here the construction and characterization of a temperature-sensitive papillomavirus mutant. the mutation is predicted to insert the sequence pro-arg-ser-arg into the n-terminal half of the bovine papillomavirus type 1 (bpv1) orf e2 protein, the major viral regulatory protein. the cloned mutant viral dna displays temperature-sensitive defects in ... | 1988 | 2841117 |
| stable expression of the hepatitis b virus surface antigen containing pre-s2 protein in mouse cells using a bovine papillomavirus vector. | the large bglii fragment (2.8 kilobases) of hepatitis b virus dna including the transcription unit for the hepatitis b surface antigen (hbsag) was inserted into a bovine papillomavirus vector containing the neomycin resistance gene. the recombinant dna was transfected into mouse c127 cells. a stable transformed cell line (ms128) secreting a large amount of 22 nm hbsag particles containing pre-s2 protein was established. the secreted hbsag particles had the receptor for polymerized human serum al ... | 1988 | 2841407 |
| evidence for cooperativity between e2 binding sites in e2 trans-regulation of bovine papillomavirus type 1. | the long control region of bovine papillomavirus type 1 (bpv-1) can function in an orientation- and position-independent manner as an e2-dependent enhancer. dissection of the long control region has revealed two e2-responsive elements, e2re1 and e2re2, which map, respectively, between nucleotides 7611 and 7806 and between nucleotides 7200 and 7386 of the bpv-1 genome. in this study, we have carried out a detailed analysis of e2re1, which has previously been shown to be involved in the regulation ... | 1988 | 2841467 |
| [warts and viruses]. | the discovery that papillomaviruses are correlated with various types of cancer in man has led to increased interest in this virus group. a more detailed study of these viruses has only become possible with the introduction of recombinant dna techniques. the most thoroughly studied representative, the bovine papillomavirus type 1, has now itself become a tool in genetic engineering. | 1988 | 2841612 |
| identification of the bovine papillomavirus l1 gene product using monoclonal antibodies. | monoclonal antibodies (moabs) produced against sds-disrupted bovine papillomavirus type 1 (bpv-1) were used to identify the product of the l1 open reading frame (orf) of bpv-1. moabs were tested in elisa with purified bpv-1 major capsid protein, fusion proteins from two constructions of the bpv-1 l1 orf, and one construction of the l2 orf. all moabs were reactive with purified mcp and both l1 fusion proteins. no moabs were identified that were reactive with the l2 fusion protein. polyclonal anti ... | 1988 | 2841806 |
| expression of human papillomavirus type 6b e2 gene product with dna-binding activity in insect (bombyx mori) cells using a baculovirus expression vector. | human papillomavirus type 6b (hpv6b) has been shown to be a major etiologic agent of genital condylomas. the e2 gene, one of the early genes, has been shown to activate the enhancer element in trans in cells transformed with bovine papillomavirus type 1a (bpv1a) but the e2 gene product of any hpv has not been identified. the e2 gene of hpv6b was inserted into the polyhedrin gene of a baculovirus, bombyx mori nuclear polyhedrosis virus (bmnpv), 156 bp downstream from the translational start codon ... | 1988 | 2842232 |
| use of a stable bovine papillomavirus vector to study inducible genes. | the human beta interferon (hifn beta 1) gene has been cloned into a bovine papillomavirus type 1 (bpv-1)/pml2 vector. the recombinant dnas can be maintained as stable plasmids in mouse cells, with no detectable rearrangements. the linked hifn beta 1 gene is inducible with little line-to-line variability in independently transformed cell lines. the hifn beta 1 gene is equally induced when it is inserted adjacent to or away from the bpv-1 enhancer. the great stability of the bpv-1/pml2 vector has ... | 1988 | 2842271 |
| initiation of viral dna replication. | | 1988 | 2843015 |
| chromosome aberrations in cattle raised on bracken fern pasture. | thirteen cows maintained on natural bracken fern (pteridium aquilinum) were analyzed cytogenetically. the frequency of structural chromosome aberrations detected in peripheral blood cells was significantly higher when compared to that detected in animals raised on pasture containing no bracken fern. we discuss the clastogenic action of fern and its synergistic action with infection by type 2 and 4 papilloma virus in the same animals. | 1988 | 2843400 |
| bovine papillomavirus e2 gene regulates expression of the viral e5 transforming gene. | we have performed transient-expression experiments with cv1 monkey kidney cells to investigate the role of the bovine papillomavirus type 1 (bpv1) e2 gene in the regulation of the e5 transforming gene. direct analysis of the 7-kilodalton open reading frame (orf) e5 protein and measurements of the expression of an e5-chloramphenicol acetyltransferase fusion protein indicate that the efficient expression of orf e5 requires the full-length e2 gene, which can be supplied in trans. the viral long con ... | 1988 | 2843663 |
| involvement of human papillomavirus type 8 genes e6 and e7 in transformation and replication. | we investigated the transforming activity of human papillomavirus type 8 (hpv8) by expressing all early open reading frames from a heterologous promoter in different rodent fibroblast lines. morphological transformation was observed only in g418-selected mouse c127 and rat 1 cells containing an intact e6-coding region. e6 of hpv8 did not transform nih 3t3 cells as did e6 of bovine papillomavirus type 1. c127 cells transformed by e6 were anchorage independent and had a reduced serum requirement b ... | 1988 | 2843666 |
| bovine papillomavirus type 1 e1 replication-defective mutants are altered in their transcriptional regulation. | bovine papillomavirus type 1 (bpv-1) is capable of replicating as a stable, high-copy-number plasmid in transformed rodent cells. the bpv-1 e1 open reading frame (orf) encodes multiple functions involved in viral dna replication. mutations which disrupt the translational integrity of the e1 orf disable the viral genome from replicating as a stable plasmid and result in the integration of the viral genome into the host chromosome generally at a low copy number. despite the low copy number of the ... | 1988 | 2845119 |
| interplay of viral and cellular proteins along the long control region of human papillomavirus type 18. | the long control region of human genital papillomavirus type 18 harbors transcription regulatory elements, such as the e6 promoter and a cell type-specific enhancer independent of the e2 protein. by performing dnase i footprint experiments in vitro with protein extracts from different cell lines and tissues we searched for cellular factors interacting with the totality of the control region. we detected a total of eight different protected sites; most of them were found with all the extracts. tw ... | 1988 | 2845145 |
| structure and expression of the guinea-pig alpha-lactalbumin gene. | the entire guinea-pig alpha-lactalbumin gene was isolated from a genomic dna library constructed in the bacteriophage lambda l47. the complete nucleotide sequence of the gene and its immediate 5' and 3' flanking sequences were determined and compared with those of the human and rat alpha-lactalbumin genes. this demonstrates that the size, organization and sequence of the exons is highly conserved between species, and reveals the presence of the highly conserved potential regulatory 'milk box' co ... | 1988 | 2845947 |
| the bovine papillomavirus p2443 promoter is e2 trans-responsive: evidence for e2 autoregulation. | the bovine papillomavirus type 1 (bpv-1) p2443 promoter is located just upstream of the e2, e3, e4 and e5 open reading frames (orfs) and is active in both transformed rodent cells and in productively infected warts. analysis of viral rna structures suggests that transcripts from this promoter encode the e2 transactivator as well as the e5 oncoprotein. to study expression of p2443, the chloramphenicol acetyltransferase (cat) reporter gene was placed downstream of this promoter, deleting the e2 an ... | 1988 | 2846284 |
| structural and mutational analysis of e2 trans-activating proteins of papillomaviruses reveals three distinct functional domains. | the e2 proteins of papillomaviruses are able to transactivate the viral enhancers by interacting with the sequence accgn4cggt found in all papillomavirus long control regions. analysis of the alignment of the amino acid sequences of 10 e2 proteins reveals three distinct regions: two partially conserved domains at the n and c termini of the proteins and a region variable in size and sequence in the middle. a computer prediction of the secondary structure of the 10 sequences outlines interesting c ... | 1988 | 2846285 |
| 44-amino-acid e5 transforming protein of bovine papillomavirus requires a hydrophobic core and specific carboxyl-terminal amino acids. | the 44-amino-acid e5 protein of bovine papillomavirus type 1 is the shortest known protein with transforming activity. to identify the specific amino acids required for in vitro focus formation in mouse c127 cells, we used oligonucleotide-directed saturation mutagenesis to construct an extensive collection of mutants with missense mutations in the e5 gene. characterization of mutants with amino acid substitutions in the hydrophobic middle third of the e5 protein indicated that efficient transfor ... | 1988 | 2847028 |
| changes in dna copy numbers of bovine papillomavirus type 1 after termination of retinoic acid treatment. | the number of bovine papillomavirus type 1 (bpv) dna copies [plasmid pdbpv-1 (142-6)] was examined in transformed c127 cells of an riii mouse during exposure to all-trans-retinoic acid (ra) and after its withdrawal. ra treatment of a transformed cell line reduced the number from approximately 60 copies to an average of less than one copy per cell within 5 weeks. the composition of the ra-treated cell population was heterogeneous with respect to bpv dna copies: 89.7% of the cells had no detectabl ... | 1988 | 2848133 |
| efficient transactivation and morphologic transformation by bovine papillomavirus genes expressed from a bovine papillomavirus/simian virus 40 recombinant virus. | to efficiently introduce bovine papillomavirus type 1 genes into cultured cells, we constructed a hybrid viral genome in which the simian virus 40 early region is replaced with a segment of the bovine papillomavirus type 1 transforming region. high-titer stocks of simian virus 40 virions containing the recombinant genome were produced in monkey cells that express simian virus 40 large tumor antigen. cells infected with this virus efficiently expressed the bovine papillomavirus type 1 e2 and e5 g ... | 1988 | 2848252 |
| cutaneous bovine papillomatosis in the sudan: detection of the group-specific virus antigen in warts from affected cattle. | | 1988 | 2848297 |
| mapping of two novel transcripts of bovine papillomavirus type 4. | a cdna library was synthesized using rna from bovine papillomavirus type 4 (bpv-4)-induced papillomas. the major viral transcript was characterized by sequencing of its cdna, primer extension mapping and s1 nuclease protection studies. the transcript initiates at multiple sites between nucleotide (nt) 777 and nt 902, contains a splice junction between nt 1016 and nt 3376 and terminates at nt 4034, using the early polyadenylation signal at nt 4009. sequencing of viral cdnas and mrna revealed devi ... | 1988 | 2848926 |
| enhancement of bovine papillomavirus-induced cell transformation by tumour promoters. | cultured c3h/10t1/2 cells transfected with the plasmid pdbpv-1 were used as targets, and the frequency of transformed colonies as the endpoint to test the enhancing capacity of four promoters: 12-o-tetradecanoylphorbol-13-acetate (tpa), 4-o-methyl-tetradecanoylphorbol-13-acetate (4-o-methyl-tpa), mezerein and phorbol-12-retinoate-13-acetate (pra). the frequency of the transfected c3h/10t1/2 cells to form transformed colonies was enhanced in the following order: mezerein greater than pra greater ... | 1988 | 2849505 |
| a dimer of bpv-1 e2 containing a protease resistant core interacts with its dna target. | the e2 proteins encoded by papillomaviruses interact with the viral dna to regulate its transcription. in the present study, we have constructed bacterial vectors expressing the full-length or n-terminal truncated bpv-1 e2 proteins under the control of an inducible promoter. by uv cross-linking experiments we show that a dimer of the intact or truncated e2 protein interacts with a single palindromic site accgnnnncggt. the dna-binding domain of e2 can be reduced to a small protease resistant core ... | 1988 | 2850174 |
| calmodulin as a regulator of cell growth and gene expression. | | 1987 | 2850611 |
| bovine papillomaviruses. | | 1985 | 2850862 |
| papilloma of the ears of calves following tattooing. | | 1988 | 2851971 |
| the e7 open reading frame of human papillomavirus type 16 encodes a transforming gene. | prior analysis of bovine papillomavirus has identified two genes, e5 and e6, which induce morphologic transformation of certain established cells. to study the transforming genes of human papillomavirus (hpv) type 16, the hpv type most commonly associated with cervical carcinoma, we examined subgenomic viral dnas under control of a retroviral long terminal repeat for their capacity to induce cellular transformation of nih 3t3 cells. plasmids carrying the entire viral early region, the e6 and e7 ... | 1988 | 2852339 |
| tumour-associated antigens in primary mouse fibroblasts induced by transformation with bovine papillomavirus type 1. | bovine papillomavirus type 1 (bpv 1) dna was used to transform primary fibroblasts of c57bl/6j mice. transformation frequency in these cells was much lower than in c127 cells and not associated with the appearance of morphologically distinct foci. however, continuous lines of transformed c57bl/6j cells were developed by serial subculturing of transfected cells. these transformed cell lines showed phenotypic properties associated with transformation including abnormal karyotypes. they contained v ... | 1988 | 2852603 |
| tumorigenicity of primary mouse fibroblasts transformed by bovine papillomavirus type 1. | cell lines transformed by bovine papillomavirus type 1 dna were established from transfected primary fibroblast cultures of c57bl/6 mice. southern blot analysis revealed that most of the viral dna in the cells was in episomal oligomeric form. these cell lines were tested for tumorigenicity in nude mice in comparison to properties associated with malignant transformation including growth in low-serum medium, focus formation in agar, and resistance to natural killer cells. two of the 5 cell lines ... | 1988 | 2852654 |
| expression of an immunoglobulin kappa light-chain gene in lymphoid cells using a bovine papillomavirus-1 (bpv-1) vector. | bovine papillomavirus-1 (bpv-1) replicates extrachromosomally in certain murine cell lines, suggesting that vectors based on the bpv-1 replicon might provide a means of obtaining more uniform gene expression among independent transformants. we have tested such a vector for the expression in hybridoma cells of the immunoglobulin kappa light-chain gene, but found that the level of expression varies greatly among transformants. our results also indicate that in these transformants the vector has pr ... | 1988 | 2853103 |
| the genetics of bovine papillomavirus type 1. | | 1988 | 2853608 |
| a novel spontaneous mutation of the bovine papillomavirus-1 genome. | a cell clone (cl.2) having an atypical transformed morphology was isolated from a murine c127 cell culture experimentally infected with a bovine papillomavirus type 1 (bpv-1) virion preparation. cl.2 cells exhibited minimal transformed characteristics and contained multiple copies of a bpv-1 plasmid with a molecular size slightly less than that of the wild type viral genome. a simple deletion of 277 bp was mapped to the distal portion of the viral 69% transforming fragment where the early gene r ... | 1988 | 2853880 |
| sequence-specific and general transcriptional activation by the bovine papillomavirus-1 e2 trans-activator require an n-terminal amphipathic helix-containing e2 domain. | the sequence-specific trans-activator protein of bovine papillomavirus (bpv)-1, e2, strongly increases transcription at promoters containing papillomaviral accg(n)4cggt (e2p) cis motifs, but can also activate a wide range of co-transfected promoters without e2p cores to a lower extent. analysis of multiple e2 mutants in transfected cells revealed that the c-terminal dna binding e2 domain binds to the e2p cis sequences in the form of pre-existing nuclear dimers. the dna binding function of e2 was ... | 1988 | 2854060 |
| r-loop mapping of rna transcripts from bovine papillomavirus type 4. | rna isolated from bovine oesophageal warts was hybridised to bpv-4 genomic dna cloned in a plasmid vector. in r-loop preparations, six major classes of transcripts were mapped. class i, due to an unspliced transcript encompassing the e4/e5 orf region, is most common. in class ii the e4/e5 region is spliced at its 5' end to the e6 orf region, and the rnas appear to have different transcription start points in the e6 orf. some class i r-loops may represent shorter class ii-type transcripts not hyb ... | 1988 | 2855468 |
| a model system for the rescue of cdna encoding transacting transcription activator by contingent replication assay. | | 1988 | 2855627 |
| transcriptional organization of bovine papillomavirus type 4. | seven virus-specific rna transcripts have been identified in tumours induced by bovine papillomavirus type 4 (bpv-4). the rnas measured 4.2, 3.6, 3.0, 2.8, 1.9, 1.6 and 1.0 kilobases (kb). they were mapped on the viral genome by northern blot hybridization to subgenomic probes, by cdna hybridization to viral dna fragments and by s1 analysis of unlabelled and 3' and 5' end-labelled dna fragments. all the rna species are transcribed from the same dna strand, are polyadenylated and with the excepti ... | 1986 | 2878058 |
| promoters and processing sites within the transforming region of bovine papillomavirus type 1. | the mrnas present in bovine papillomavirus type 1 (bpv-1)-transformed c127 cells were studied by primer extension. the results show that two internal promoters are present in the e region of bpv-1 in addition to the previously identified promoter at coordinate 1 (h. ahola, a. stenlund, j. moreno-lópez, and u. pettersson, nucleic acids res. 11:2639-2650, 1983). one, located at coordinate 31, generated a set of mrnas with heterogeneous 5' ends, which may encode the major transforming protein of bp ... | 1987 | 2884331 |
| the leeuwenhoek lecture, 1986. environmental carcinogens and papillomaviruses in the pathogenesis of cancer. | in many areas of the world there is a geographically localized high incidence of alimentary and bladder cancer in cattle. studies in western scotland have demonstrated that this phenomenon is associated with ingestion of bracken fern. however, the affected animals and herds were shown also to have an unusually high infection rate of alimentary papillomas caused by a previously unrecognised bovine papillomavirus (bpv) and that these tumors could undergo malignant transformation. long-term field a ... | 1987 | 2888116 |
| nucleotide sequence of bovine papillomavirus type 2 late region. | the late region of bovine papillomavirus type 2 (bpv-2) dna has been identified. the complete nucleotide sequence of the region was determined and revealed two large open reading frames. the dna sequence results and the predicted amino acid sequence of putative polypeptides encoded by this region are presented. comparative analysis of the bpv-2 late region and the corresponding area of bpv-1 was performed. this study demonstrates that identical genetic organization and considerable nucleotide se ... | 1985 | 2981958 |
| genetic analysis of bovine papillomavirus type 1 trans-acting replication factors. | the establishment of bovine papillomavirus type 1 in somatic mammalian cells is mediated by extrachromosomal replication and stable maintenance of the viral genome as a multicopy nuclear plasmid. previous studies indicated the requirement of viral gene expression for bovine papillomavirus type 1 replication and plasmid maintenance (m. lusky and m. r. botchan, cell 36:391-401, 1984; turek et al., proc. natl. acad. sci. u.s.a. 79:7914-7918, 1982). to define the viral genes which are necessary for ... | 1985 | 2983102 |
| bovine papillomavirus contains multiple transforming genes. | bovine papillomavirus type 1 (bpv-1) and its cloned full-length dna can transform rodent cells in vitro, and the viral dna persists as an extrachromosomal multicopy plasmid in these transformed cells. previous studies have identified at least five discrete viral rnas that are expressed in bpv-1 transformed cells and have shown that these transcripts share a 3' coterminus. to further define the structure of these rnas and to characterize the functions of individual viral transcripts, we construct ... | 1985 | 2983327 |
| the biology of papillomaviruses and their role in oncogenesis. | a large number of different papillomavirus types have been identified. several viruses often infect the same species and each virus is associated with a defined tissue. recent evidence has shown that certain benign lesions can undergo malignant transformation in both animals and humans in response to genetic or environmental factors. fine mapping of the structure and function of the viral genome may enhance our understanding of the interaction between the virus and the cofactors involved in mali ... | 1985 | 2986520 |
| transformation of cultured equine fibroblasts with a bovine papillomavirus. | fetal equine fibroblasts exposed to bovine papillomavirus became transformed by the criteria of morphological alterations and the acquisition of an increased life span, although they failed to grow in soft agar. papillomavirus genome persisted in the transformed fibroblasts and was apparently not integrated with the cellular genome. these findings support the notion that bovine papillomaviruses are involved in the production of equine sarcoids. | 1985 | 2988095 |
| messenger rnas from the transforming region of bovine papilloma virus type i. | messenger rnas present in c127 mouse cells transformed by bovine papilloma virus type 1 (bpv-1) were studied by the s1 nuclease protection technique, northern blotting, and electron microscopic heteroduplex analysis. the results revealed at least five classes of spliced mrnas which we designate types 1 to 5. they had a common poly(a) addition site located at co-ordinate 53 and all mrnas, except the type 3 mrnas, contained an exon located between co-ordinates 41 and 53. in the type 1 mrnas this e ... | 1985 | 2989533 |
| bovine papillomavirus type 1 monoclonal antibodies. | bovine papillomavirus type 1 (bpv-1) and type 2 (bpv-2) are the etiologic agents of fibropapillomas in cattle. polyclonal antisera produced against bpv-1 structural antigens are cross-reactive with bpv-2. in this study bpv-1 type-specific monoclonal antibodies were produced that were not reactive with bpv-2. these monoclonal antibodies could be used for identification of bpv-1 structural antigens in acetone-fixed, frozen sections by immunofluorescence and formalin-fixed, paraffin-embedded sectio ... | 1985 | 2989600 |
| expression of a functional influenza viral cap-recognizing protein by using a bovine papilloma virus vector. | the gene for the influenza viral pb2 protein, which recognizes and binds the 5'-terminal cap 1 structures (m7gpppnm) on eukaryotic mrnas, was inserted into a bovine papilloma virus vector under the control of a mouse metallothionein i (mt-i) promoter. after transfection of this vector into mouse nih 3t3 cells, a cell line, cpb2, was obtained that produces pb2-specific mrna and authentic pb2 protein. induction of the mt-i promoter with cdcl2 causes about a 10-fold increase in pb2 mrna and protein ... | 1985 | 2989815 |
| transactivation of a bovine papilloma virus transcriptional regulatory element by the e2 gene product. | we have mapped a transcriptional regulatory sequence within the 1.0 kb noncoding region of the bovine papilloma virus (bpv-1) genome, using an enhancer dependent expression vector for chloramphenicol acetyltransferase. this transcriptional regulatory element works independently of position and orientation, and its function is significantly augmented in bpv-1 transformed c127 cells and in monkey cv-1 cells acutely transfected with plasmids expressing bpv-1 early gene products. using defined delet ... | 1985 | 2990724 |
| lines of bpv-transformed murine cells that constitutively express influenza virus hemagglutinin. | we have developed and characterized several murine cell lines that constitutively express either the full-length, membrane-bound form of influenza virus hemagglutinin (ha) or a truncated version of the protein (hasec) that lacks the carboxyterminal anchoring sequences and is secreted from cells. cdnas encoding ha or hasec were linked to the murine metallothionein-i promoter or the sv40 early promoter, and inserted into plasmids containing the transforming dna fragment of bovine papilloma virus ( ... | 1985 | 2990897 |
| the presence of bovine papillomavirus type 4 dna is not required for the progression to, or the maintenance of, the malignant state in cancers of the alimentary canal in cattle. | in the western highlands of scotland there is a very high incidence of alimentary cancers in cattle. the carcinomas of the upper alimentary canal are found in association with virus-induced benign papillomas, and transformation of papillomas to carcinomas has been observed. strong circumstantial evidence suggests that the progression to malignancy is due to the interplay between the virus, bovine papillomavirus type 4 (bpv-4), and carcinogen(s) present in bracken fern, which infests the marginal ... | 1985 | 2992946 |
| molecular cloning and nucleotide sequence of deer papillomavirus. | the genome of deer papillomavirus (dpv) isolated from american white-tailed deer was cloned into pbr322, and the entire nucleotide sequence of 8,374 base pairs was determined. the overall genetic organization of the dpv genome was similar to that of other papillomaviruses. all significant open reading frames were located on one strand, and the locations of putative promoters and polyadenylation signals were similar to those identified in the closely related bovine papillomavirus type 1 (bpv-1) g ... | 1985 | 2993669 |
| high spontaneous mutation frequency of bpv shuttle vector. | a recombinant shuttle vector containing the entire bovine papillomavirus (bpv) genome, sequences from pbr322, and the escherichia coli gpt gene was used to transform mouse c127 cells. plasmid extracted from the transformed mouse cells was used to transform a gpt- derivative of e. coli hb101, and the relative frequency of plasmids carrying a mutation in the gpt gene was determined. approximate mutant frequencies of 3-16 x 10(-3) were observed for plasmid molecules which had been passaged through ... | 1985 | 2994240 |