Publications

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
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
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
"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
enhanced production of hepatitis b virus surface antigen in mouse c127 cell on a bovine papillomavirus-metallothionein vector.	we have constructed a recombinant plasmid pcps12 containing the hepatitis b viral surface antigen (hbsag) gene linked to the mouse metallothionein promoter on a bpv-pml2 vector. two stable clones s12-8 and s12-2, obtained by transfection of the mouse c127 cells with pcps12 propagated in dam+ dcm+ and dam- dcm- escherichia coli respectively, exhibited different types of response to 5-azacytidine (5-aza-cr) and cadmium (cd) induction. in s12-8, the productivity of hbsag was enhanced by 5-aza-cr or ...	1988	2451524
a transfected alpha-casein minigene bypasses posttranscriptional control by hormones, but retains cell-substratum regulation in mammary epithelial cells.	dna-mediated gene transfection using an alpha-casein minigene cloned into a bovine papilloma virus (bpv)-based neomycin-selectable expression vector has been employed to study the mechanisms by which hormonal and cell-substratum interactions regulate milk protein gene expression. permanently transformed clones and pooled populations of normal midpregnant mouse mammary epithelial cells (comma-d) containing the minigene express an authentic rat alpha-casein mrna, as well as a series of larger cyto ...	1988	2458523
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
expression of human epidermal growth factor precursor cdna in transfected mouse nih 3t3 cells.	stable cell lines expressing the human epidermal growth factor (egf) precursor have been prepared by transfection of mouse nih 3t3 cells with a bovine papillomavirus-based vector in which the human kidney egf precursor cdna has been placed under the control of the inducible mouse metallothionein i promoter. synthesis of the egf precursor can be induced by culturing the cells in 5 mm butyric acid or 100 microm zncl2. the egf precursor synthesized by these cells appears to be membrane associated; ...	1988	3257563
expression and processing of a recombinant human macrophage colony-stimulating factor in mouse cells.	a human macrophage colony-stimulating factor encoded by a 4-kilobase cdna was expressed with bovine papillomavirus vectors in mouse cells. pulse-chase analyses revealed that the 62-kilodalton (kda) translation product was glycosylated, cleaved, and efficiently secreted within 1 h of synthesis. the secreted product contained both n-linked and o-linked oligosaccharide chains. macrophage colony-stimulating factor was present extracellularly as an 80-kda homodimer and as a multimeric species of grea ...	1988	3264878
human growth hormone gene and the highly homologous growth hormone variant gene display different splicing patterns.	stably transfected cell lines containing the normal human growth hormone (hgh-n) and human growth hormone-variant (hgh-v) genes have been established in order to study the expression of these two highly homologous genes. each gene was inserted into a bovine papillomavirus shuttle vector under the transcriptional control of the mouse metallothionein gene promoter and the resultant recombinants were transfected into mouse c127 cells. the transfected cells containing the hgh-n gene secrete two hgh ...	1988	3392209
stability of a bacterial gene in a bovine papillomavirus-based shuttle vector maintained extrachromosomally in mammalian cells.	in order to analyse the stability of cloned genes in a viral vector we have constructed a shuttle vector based on bovine papillomavirus and the escherichia coli gene lacz. propagation of this vector in mouse c127 cells and analysis of vector sequences in bacteria produced no detectable mutations in the lacz gene in over 6137 clones analysed. this is 100-fold less than the mutation frequency observed when the same and similar target genes are replicated in monkey cos cells using a simian virus 40 ...	1987	3027246
mutational analysis of open reading frame e4 of bovine papillomavirus type 1.	open reading frame (orf) e4 is a 353-base-pair orf of bovine papillomavirus type 1. to determine the biological activities of this orf in mouse c127 cells, we analyzed the effects of two constructed mutations which are predicted to prevent synthesis of orf e4 proteins while leaving the amino acid sequence encoded by the overlapping orf e2 unchanged. neither mutation interfered with the abilities of the mutants to efficiently induce focus formation, induce growth in soft agarose, or transactivate ...	1987	3029420
bovine papillomavirus transcriptional regulation: localization of the e2-responsive elements of the long control region.	the long control region (lcr) of the bovine papillomavirus type 1 genome can function as a conditional transcriptional enhancer which can be specifically trans-activated by the viral e2 gene product. to precisely map the target(s) of this trans-activation, bal 31 exonuclease was used to generate two overlapping series of deleted dna segments through the lcr. these fragments were assayed for their ability to activate transcription from the enhancer-deleted simian virus 40 early promoter of pa10ca ...	1987	3035214
methods for analyzing bovine papilloma virus-based calmodulin expression vectors.		1987	3035329
assessment of precancerous lesions of the uterine cervix for evidence of human papillomavirus infection: a histological and immunohistochemical study.	cervical biopsies obtained by colposcopic direction from 358 women were histologically examined for squamous dysplasia (cervical intra-epithelial neoplasia; cin) and human papillomavirus (hpv) infection. of the 358 biopsies, 136 were stained by an immunoperoxidase method using an antiserum against genus-specific (common) antigen of bovine papillomavirus. hpv antigens were detected in 40% of biopsies showing definite histological evidence of hpv effect, and in 7.9% and 2.6% of those with possible ...	1987	3035470
[genetic transformation of somatic cells. xi. the autonomic replication of the cloned dna of the bovine papilloma virus in nih/3t3 mouse fibroblasts and the changes in the growth characteristics of the transformed cells].	mouse fibroblasts nih 3t3 were transfected with the plasmid pbpv (142-6) containing full genome of bovine papilloma virus 1, and focuses of morphological transformation were selected 2-3 weeks later. dna molecules, containing bpv-1 sequences, were isolated from extrachromosomal fraction of transformed clones suggesting stable autonomous replication of bpv in 3t3 nih cells. in some rescued plasmids deletions spanning e6, 7 genes of bpv were found. it is suggested that these genes are not essentia ...	1987	3035762
bovine papilloma virus plasmids replicate randomly in mouse fibroblasts throughout s phase of the cell cycle.	bovine papilloma virus (bpv) replicates as a multicopy nuclear plasmid in mouse fibroblasts. using fluorescence activated cell sorting and mitotic selection procedures, we show that the replication of bpv occurs throughout s phase of the cell cycle and that replication is confined to s phase. after one round of chromosomal dna replication, almost one quarter of bpv plasmids have replicated more than once, while a similar number of plasmids have not replicated at all. while multiple forms of bpv ...	1987	3036365
a transcriptional repressor encoded by bpv-1 shares a common carboxy-terminal domain with the e2 transactivator.	a negative-acting transcriptional regulatory factor encoded by bovine papillomavirus type 1 (bpv-1) was identified. this factor inhibits bpv-1-mediated transformation of mouse c127 cells; inhibition is bpv-1-specific and occurs only when the bpv-1 transforming genes are regulated by authentic transcriptional control elements. plasmids expressing the inhibition function also repress e2 transactivation of the bpv-1 e2-dependent enhancer, and this repression is mediated by the same cis-acting eleme ...	1987	3036366
differential promoter utilization by the bovine papillomavirus in transformed cells and productively infected wart tissues.	expression of the 'late' genes of bovine papillomavirus type 1 (bpv-1) occurs only in the differentiated keratinocytes of the productively infected fibropapilloma. a detailed analysis of viral transcription in the fibropapilloma was performed and compared to bpv-1 specific transcription in transformed c127 cells. a cdna library was constructed from bovine fibropapilloma mrna using the method of okayama and berg. analysis of full length cdnas showed that the majority of viral transcripts in the f ...	1987	3036488
identification of the hpv-16 e6 protein from transformed mouse cells and human cervical carcinoma cell lines.	human cervical carcinoma cell lines that harbor human papillomavirus (hpv) have been reported to retain selectively and express hpv sequences which could encode viral e6 and e7 proteins. the potential importance of hpv e6 to tumors is suggested further by the observation that bovine papillomavirus (bpv) e6 can induce morphologic transformation of mouse cells in vitro. to identify hpv e6 protein, a polypeptide encoded by hpv-16 e6 was produced in a bacterial expression vector and used to raise an ...	1987	3036495
measurement of cell-mediated immunity against bovine papilloma virus by lymphoproliferative reactions.	to study cellular immunity towards bovine papillomavirus (bpv), calves were infected intradermally with bpv-1, and the cellular immune response was measured by the lymphocyte proliferation assay. peripheral blood lymphocytes were obtained which in control experiments were highly reactive towards mitogen stimulation. different batches of bpv-1 were prepared by the use of density gradients. in the first set of experiments, a nonspecific mitogenic effect of the virus preparation was observed. this ...	1987	3036693
purification of papillomavirus structural polypeptides from papillomas by immunoaffinity chromatography.	a broadly cross-reactive monoclonal antibody directed against papillomavirus, coupled to immunoaffinity columns, was used to isolate bovine papillomavirus type 1 (bpv-1) and human papillomavirus type 1 (hpv-1) structural polypeptides from homogenates of productively infected cells. one of the polypeptides isolated from bovine fibropapillomas appeared to be the bpv-1 major capsid protein since it had a mol. wt. of 54k and was reactive by western blots with papillomavirus genus- and bpv-1 type-spe ...	1987	3037012
expression of human papillomavirus types 6b and 16 l1 open reading frames in escherichia coli: detection of a 56,000-dalton polypeptide containing genus-specific (common) antigens.	the human papillomavirus (hpv) genome contains two large open reading frames (orfs), designated l1 and l2. to characterize the antigenic properties of the l1 orf-encoded proteins, we cloned the l1 orfs of hpv6b and hpv16 in plasmids, and these were expressed in escherichia coli. first, the hpv6b dna, representing 85.2% of the l1 orf, was cloned in puc19 and expressed in e. coli jm83 and rb791 as a 160,000-molecular-weight (160k) fusion protein with e. coli beta-galactosidase (6bl1/beta-gal). sec ...	1987	3037103
human papillomavirus types 6 and 11 mrnas from genital condylomata acuminata.	we have identified and mapped a number of rna species of human papillomavirus types 6 and 11 from condylomata acuminata by the electron microscopic r-loop technique. each of the early (e)- and late (l)-region open reading frames (orfs) deduced from the dna sequences was represented in one or more transcripts. in addition, rna species that could encode the modulator of dna replication and the repressor of transcription, functions recently identified in the genetically similar bovine papillomaviru ...	1987	3037118
enhancers and trans-acting e2 transcriptional factors of papillomaviruses.	the upstream regulatory regions of human papillomavirus (hpv) types 1, 6b, 7, 11, 16, and 18, bovine papillomavirus type 1, and cottontail rabbit papillomavirus were cloned into transcriptional enhancer assay plasmids which carry the simian virus 40 early promoter lacking its own enhancer and the bacterial gene encoding chloramphenicol acetyltransferase (ec 2.3.1.28) (cat). enhancer activity, reflected by cat gene expression, was detected in all of the upstream regulatory regions tested only whe ...	1987	3037119
nucleosomal organization of a bpv minichromosome containing a human h4 histone gene.	to address the relationship between chromatin structure and histone gene expression, the nucleosomal organization of a cell cycle-dependent human h4 histone gene in a bovine papilloma virus (bpv) minichromosome was examined. the nucleosome repeat length of the human h4 histone gene, maintained as a stable episome in a c127 mouse cell line designated i-8, was compared with that of the chromosomal copy of the h4 gene in human (hela) cells. in both cell lines, the h4 histone gene is predominantly e ...	1987	3037307
nucleotides in the polyomavirus enhancer that control viral transcription and dna replication.	the polyomavirus enhancer is required in cis for high-level expression of the viral early region and for replication of the viral genome. we introduced multiple mutations in the enhancer which reduced transcription and dna replication. polyomaviruses with these mutant enhancers formed very small plaques in whole mouse embryo cells. revertants of the viral mutants were isolated and characterized. reversion occurred by any of the following events: restoration of guanosines at nucleotide (nt) 5134 ...	1987	3037332
a promoter with an internal regulatory domain is part of the origin of replication in bpv-1.	extrachromosomal elements that are stably maintained at a constant copy number through cell doublings are a good model system for the study of the regulation of dna replication in higher eukaryotes. previous studies have defined both cis and trans functions required for the regulated plasmid replication of the bovine papilloma virus in stably transformed cells. here, a sequence known to be a cis-dominant element of the replication origin of the plasmid is shown to contain a promoter for transcri ...	1987	3037693
the nucleotide sequence and genome organization of bovine papillomavirus type 4.	the nucleotide sequence of bovine papillomavirus type 4 (bpv-4) was determined. the viral genome is 7261 base pairs long. several overlapping open reading frames (orfs) have been identified both on the basis of amino acid comparison with other papillomaviruses and on their transcriptional pattern. eight early orfs (e1 to 8) were recognized, coding for dna replication and cell transformation functions, and three late orfs (l1 to 3), coding for structural proteins. like the e5 orf of human papillo ...	1987	3039043
identification of proteins encoded by the l1 and l2 open reading frames of human papillomavirus 1a.	the human papillomavirus 1 (hpv-1) virion is composed of two virally encoded proteins: a 57,000-molecular-weight polypeptide (57k polypeptide), which is the product of the l1 open reading frame (orf), and a 78k polypeptide, which is derived from the l2 orf. the 57k (l1) product, which represents the major structural component, appears to be disulfide cross-linked in virus particles. the 78k (l2) protein is a minor component of the virion and does not appear to be disulfide linked either to the l ...	1987	3039170
levels of bovine papillomavirus rna and protein expression correlate with variations in the tumorigenic phenotype of hamster cells.	three independent cell lines were established from primary cultures of lsh hamster embryo cells infected with bovine papillomavirus type 1 (bpv-1). although these cell lines differed in their in vitro saturation densities, none was capable of colony formation in soft agar. interestingly, two cell lines (bpv-he1 and bpv-he3) were tumorigenic in nude mice, syngeneic hamsters, and allogeneic hamsters, whereas bpv-he2 was not. all three cell lines contained similar numbers of the bpv-1 genome (appro ...	1987	3039179
contingent replication assay (cra) procedure for rapid isolation of enhancers.	a rapid procedure for the isolation of functional enhancer sequences consists of the construction of a shotgun dna library in sv40-based plasmid shuttle vectors which depend on an enhancer for replication, the replication in monkey (cvi) cells of those vectors into which an enhancer sequence was inserted, the selective cleavage of unreplicated vectors by dpni and the recovery of the replicated vectors by transfection into escherichia coli. we describe conditions for the fusion of protoplasts to ...	1987	3040530
demonstration that a chemically synthesized bpv1 oncoprotein and its c-terminal domain function to induce cellular dna synthesis.	bovine papillomavirus type 1 contains the smallest known oncogene (orf e5), encoding a hydrophobic 44 amino acid protein. to study the biochemical functions of the e5 oncoprotein, we have chemically synthesized it and several deletion mutant peptides. we demonstrate induction of cellular dna synthesis in growth-arrested cells by microinjection of e5 oncoprotein. this activity can be broken down into two functionally distinguishable domains. remarkably, the first domain, which alone is sufficient ...	1987	3677173
[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
bovine papillomavirus e2 trans-activating gene product binds to specific sites in papillomavirus dna.	enhancers are cis-acting elements that activate transcription in higher eukaryotes independently of their position or orientation relative to the promoter that they activate. the mechanisms by which enhancers activate transcription are poorly understood, in part because, with the exception of the glucocorticoid receptor, the proteins that directly interact with enhancers have not been purified, nor have the genes encoding them been cloned. the upstream regulatory region (urr) that immediately pr ...	1987	3025749
the e2 "gene" of bovine papillomavirus encodes an enhancer-binding protein.	the e2 early open reading frame (presumably gene) of bovine papillomavirus-1 was fused in frame with the collagen-beta-galactosidase-encoding region of the vector pjg200 and was expressed in and partially purified from escherichia coli. the hybrid protein specifically bound to the enhancer region of bovine papillomavirus at several sites. dnase i-cleavage protection analysis of one such site revealed the protected sequence. a comparison of the protected sequence with the remainder of the dna seq ...	1987	3029771
episomal maintenance of a bovine papilloma virus vector in transgenic mice.	we have used a bovine papillomavirus-based vector to generate transgenic mice. transgenic mice result from either pronuclear or cytoplasmic injections of the vector into fertilized eggs. of 30 mice generated by microinjection, 27 (90%) contained the vector in its episomal form, at less than one copy per cell. this represents a highly efficient means of gene transfer in which the transgene is in a controlled genetic environment.	1987	3031486
human papillomavirus type 17 transcripts expressed in skin carcinoma tissue of a patient with epidermodysplasia verruciformis.	certain types of human papillomavirus (hpv) are involved in skin carcinogenesis in epidermodysplasia verruciformis. however, no gene or gene product of hpv associated with skin carcinogenesis has yet been identified. here, we report hpv-17 transcripts expressed in skin carcinoma tissue of an epidermodysplasia verruciformis patient infected with hpv-17. further, we show that one of these transcripts was localized to a portion of the genome which contains the 3' open reading frames of the early re ...	1987	3032809
transcriptional trans-activation by the human papillomavirus type 16 e2 gene product.	we identified a conditional transcriptional enhancer in the long control region (lcr) of human papillomavirus type 16 (hpv-16). this conditional enhancer requires activation in trans by a product of the viral early-region open reading frames (orfs). primer extension analysis of chloramphenicol acetyltransferase rna isolated from transiently transfected cv-1 cells demonstrated that trans-activation of the hpv-16 lcr enhancer operated at the transcriptional level. mutational analysis of the early ...	1987	3033289
dna-binding activity of papillomavirus proteins.	we demonstrate dna binding by papillomavirus (pv) open reading frame (orf) proteins that correspond to the early transforming and trans-activating (e6 and e2) and late structural regions (l2 and l1) from bovine pv type 1 and human pv types 6b and 16. all pv proteins were synthesized in escherichia coli and had a common 13-amino-acid leader sequence from the expression vector pra10. antibodies have been generated in rabbits against these pv proteins. the pv orf proteins bind double-stranded dna, ...	1987	3033292
trans-activation of an upstream early gene promoter of bovine papilloma virus-1 by a product of the viral e2 gene.	the approximately 1000 nucleotide long upstream regulatory region (urr) of bovine papilloma virus-1 (bpv-1) contains a cis element which responds to trans-activation by a diffusible factor encoded in the viral e2 open reading frame (orf). a series of urr dna fragments have been linked to two heterologous genes, bacterial chloramphenicol acetyl transferase (cat) or herpes simplex virus-1 thymidine kinase (tk), and tested in transient transfection assays for transcription initiating at the authent ...	1987	3034572
characterization of recombinant human granulocyte-colony-stimulating factor produced in mouse cells.	mouse c127i cells were transformed with a chimeric plasmid consisting of bovine papillomavirus dna and human granulocyte-colony-stimulating factor (g-csf) cdna placed under the control of the sv40 early promoter. the transformed cells secreted constitutively a high level of human g-csf, 10-20 micrograms/ml in a low-serum medium. the secreted g-csf has been purified to homogeneity by a two-step procedure including gel filtration and hydrophobic column chromatography. the purified recombinant g-cs ...	1987	3034599
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
gonadotropin beta subunits determine the rate of assembly and the oligosaccharide processing of hormone dimer in transfected cells.	the glycoprotein hormones lutropin (lh) and chorionic gonadotropin (cg) share a common structure consisting of an identical alpha subunit noncovalently linked to a hormone-specific beta subunit. while lh is produced in the anterior pituitary, cg is synthesized in placenta. to compare the assembly, processing, and secretion of human lh and cg in the same cell type, we have expressed their subunits, individually and together, in mouse c-127 mammary tumor cells. analysis of transfected clones revea ...	1987	2437127
expression of the human papillomavirus type 6b l2 open reading frame in escherichia coli: l2-beta-galactosidase fusion proteins and their antigenic properties.	human papillomavirus (hpv) type 6b genome contains two large open reading frames (orfs), designated l1 and l2, in a putative late region. these orfs are expected to code for viral structural proteins. to examine antigenic properties of a l2 gene product, we constructed two plasmids which contain n-terminal (l2-n) and internal (l2-i) regions of the hpv6b l2 orf and then each region was expressed in escherichia coli as a fusion protein with e. coli beta-galactosidase (beta-gal). both l2-n/beta-gal ...	1987	2437699
expression of human papillomavirus type 6 e1, e2, l1 and l2 open reading frames in escherichia coli.	open reading frame (orf) fragments (putative gene fragments) from human papillomavirus type 6b (hpv-6b) were inserted into the bacterial expression vector phk413 to provide viral antigenic determinants. approximately 86% of the entire l1 orf, 82% of the e2 orf, and 52% of the l2 orf were expressed in escherichia coli. the e1 orf was cloned as two fragments. the constructions containing e1n (coding for the n-terminal region) and e1c (coding for the c-terminal region) expressed 27% and 16% of the ...	1987	2445631