| induction of bovine papillomavirus e2 gene expression and early region transcription by cell growth arrest: correlation with viral dna amplification and evidence for differential promoter induction. | the bovine papillomavirus type 1 (bpv-1) genome replicates as a latent plasmid in mouse c127 cells transformed in vitro by the virus. however, we have recently shown that bpv-1 dna amplification can be induced in a subpopulation of cells under culture conditions which suppress cell proliferation, a finding which led us to hypothesize that expression of a viral replication factor was regulated by cell growth stage. in this report, we describe the detection in these cells of abundant bpv-1 nuclear ... | 1990 | 2170685 |
| the e6/e7 promoter of human papillomavirus type 16 is activated in the absence of e2 proteins by a sequence-aberrant sp1 distal element. | the e6/e7 promoter of all genital human papillomaviruses is responsible for expression of the viral transforming genes. centered 60 bp upstream of the transcription start, it contains a 20-bp segment with partially overlapping binding sites for the viral e2 proteins and for a cellular factor that was identified by footprint experiments. bandshifts, bandshift competitions, and footprints revealed that protein complexes between nuclear extracts and these sequences have binding properties indisting ... | 1990 | 2170687 |
| complementation of a vesicular stomatitis virus glycoprotein g mutant with wild-type protein expressed from either a bovine papilloma virus or a vaccinia virus vector system. | using a complementation assay, we have evaluated the potential of two eukaryotic expression systems to produce functional virus proteins. the first expression system was based on a bovine papilloma virus (bpv) eukaryotic expression vector which contained a copy of the gene for the membrane glycoprotein g of vesicular stomatitis virus (vsv). this vector was transfected into a mouse cell line, and transformed cell clones constitutively expressing vsv g protein were selected. these cell clones were ... | 1990 | 2171187 |
| adenovirus infection induces amplification of persistent viral dna sequences (simian virus 40, hepatitis b virus, bovine papillomavirus) in human and rodent cells. | adenoviruses, types 2 and 12 induce amplification of sv40 dna sequences in cells of the sv40-transformed human newborn kidney cell line, nb-e. similarly, integrated hepatitis b virus dna sequences in the human hepatoma cell line, plc/*prf/5, and bovine papillomavirus (bpv) dna sequences in bpv-transformed mouse cells (id13) are amplified by adenovirus infection. thus, similar to herpes group or vaccinia viruses or dna damaging agents, adenoviruses are able to mediate selective dna amplification ... | 1990 | 2171240 |
| production and characterization of a fragment containing the hiv-gp120 binding region of cd4 using a bovine papilloma virus (bpv) vector. | we have used a bovine papilloma virus (bpv) based mammalian cell expression vector consisting of the complete bpv genome and a human cytomegalovirus transcription unit for the production of soluble cd4. mouse c-127 cells were transfected with vector dna together with a selectable g418 resistance plasmid. surviving clones were selected for high production using a solid phase elisa based on the immobilization of supernatant-derived cd4 onto nitrocellulose paper and subsequent detection with anti-c ... | 1990 | 2171457 |
| replication of bovine papillomavirus type 1 dna initiates within an e2-responsive enhancer element. | when bovine papillomavirus transforms cells in vitro, it maintains its genome as a multicopy nuclear plasmid. plasmid dna extracted from such transformed cells was analyzed by the two-dimensional gel electrophoresis technique of brewer and fangman (b. brewer and w. fangman, cell 51:463-471, 1987). the replication intermediates detected in these assays were found to be the sums of the oligomeric and monomeric forms of the replicating plasmids. the multimeric dnas were shown by field inversion gel ... | 1990 | 2173772 |
| proteins encoded by the bovine papillomavirus e1 open reading frame: expression in heterologous systems and in virally transformed cells. | the e1 open reading frame (orf) of bovine papillomavirus type 1 is required for the persistence of viral genomes as multicopy plasmid molecules in transformed rodent fibroblasts. e1 has been reported to contain two separate complementation groups (m and r, corresponding to n- and c-terminal domains, respectively) which regulate viral replication. however, e1 behaves as a single gene with respect to cell transformation and viral transcription. we examined the proteins translated from the entire o ... | 1990 | 2173778 |
| local immune reaction in syngeneic mice against tumorigenic and nontumorigenic bpv-transformed mouse cell lines. | the role of cytotoxic t cells in immune response to bovine papillomavirus type 1 (bpv1)-transformed mouse cell lines was assessed. the chromium release assay was used to follow the induction of cytotoxicity in local lymph nodes of syngeneic c57bl/6j (b6) mice after injection of bpv1-transformed cell lines tumorigenic in nude mice but tumorigenic or nontumorigenic in b6 mice. the nontumorigenic cell line b6b31.c-nut.a induced cell line-specific cytotoxicity with a maximal activity on day 7 after ... | 1990 | 2173935 |
| non-selective analysis of the transformation of fr3t3 rat cells by bovine papillomavirus type 1: regulations of viral transcription associated with phenotypic transformation. | drug-resistant clones selected from fr3t3 rat cells after transfer of neo-bpv1 (bovine papillomavirus type 1) dna constructs became phenotypically transformed (focal transformation, growth in suspension and tumor formation) soon after selection (approximately 5 generations in culture). a frameshift mutation in orf e5 abolished transformation, but did not prevent the autonomous maintenance of the dna construct. a more complex situation was observed when the e2 transactivating function was abrogat ... | 1990 | 2176280 |
| targeting the e1 replication protein to the papillomavirus origin of replication by complex formation with the e2 transactivator. | the mechanism by which transcription factors stimulate dna replication in eukaryotes is unknown. bovine papillomavirus dna synthesis requires the products of the viral e1 gene and the transcriptional activator protein encoded by the e2 gene. experimental data showed that the 68-kilodalton (kd) e1 protein formed a complex with the 48-kd e2 transcription factor. this complex bound specifically to the viral origin of replication, which contains multiple binding sites for e2. repressor proteins enco ... | 1990 | 2176744 |
| cooperation between bovine papillomavirus type 4 and ras in the morphological transformation of primary bovine fibroblasts. | primary bovine fibroblasts derived from foetal palate can be transformed by bovine papillomavirus type 4 dna only in the presence of an activated ras gene, indicating that the virus does not encode all the information required for morphological transformation of non-established cells. a subgenomic fragment containing the complete e8 and e7 open reading frames (orfs) induces transformation in cooperation with activated ras but transformation is abolished when the e7 orf is deleted at the 3' end, ... | 1990 | 2177095 |
| homologous recombination in a mammalian plasmid. | bovine papillomavirus (bpv) shuttle vectors replicate as a circular plasmid in mouse cell nuclei without impairing host cell viability. we used these vectors to analyze homologous recombination in mammalian cells. when several bpv-based plasmids carrying direct repeats were introduced into c127 cells, we detected many recombinant plasmid molecules that have lost the sequence between the repeats. many recombinant type molecules as well as parental type molecules were detected in all the cell clon ... | 1990 | 2177135 |
| bovine serological response to a recombinant bpv-1 major capsid protein vaccine. | four of five groups of holestine by angus calves (5 calves/group) were immunized with different formulations of a recombinant bpv-1 dna vaccine using a bpv-1 major capsid:b-galactosidase fusion protein as the immunogen. group 5 was not vaccinated. vaccinated calves received the vaccine on days 0 and 21 of the trial, and calves from all five groups were challenged intradermally with 10(10) bpv-1 particles at each of two different sites on day 56. all calves were bled on days 3, 24, 55, 77, and 10 ... | 1990 | 2177743 |
| detection of papillomavirus dna in precancerous lesions of the ears of sheep. | sixty-seven benign precancerous cutaneous lesions from the ears of 51 sheep were examined for papillomavirus dna by hybridisation to radioactively labelled or biotinylated probes of bovine papillomavirus type 1 (bpv 1) dna under varying conditions of stringency. an additional 16 precancerous lesions from other cutaneous sites on 15 sheep and 15 samples of lesion-free skin from nine sheep were similarly examined. both total genomic and subgenomic probes were used. dna from 10 aural lesions and on ... | 1990 | 2177931 |
| studies on the transmission of viral disease via the co2 laser plume and ejecta. | while recent reports have noted the presence of viral dna sequences in the laser plume, no significant effort has been made to study transmission of the virus in vivo via airborne laser debris. studies were undertaken to identify potential hazards to operating room occupants in gynecologic laser surgery. aco2 laser in the continuous wave mode using a power density of 666 w/cm2 was fired through a 5-cm metal cylinder at virus-infected tissues. airborne particulate debris, 100-200 microns, was rem ... | 1990 | 2178190 |
| overexpressed human metallothionein iia gene protects chinese hamster ovary cells from killing by alkylating agents. | experiments were designed to detect survival advantages that cells gain by overexpressing metallothionein (mt). chinese hamster ovary k1-2 cells and an x-ray-sensitive derivative were transfected with a bovine papillomavirus (bpv)-linked construct carrying the human metallothionein iia (hmt-iia) gene. transfectants survived 40-fold higher levels of cadmium chloride, harbored at least 30 copies of hmt-iia, and contained 25- to 166-fold more mt than the parent cells. even under conditions of reduc ... | 1990 | 2320583 |
| detection of papillomaviruses in cutaneous fibromas of white-tailed and mule deer. | naturally occurring cutaneous fibromas affecting white-tailed deer (odocoileus virginianus) and mule deer (o hemionus), and cutaneous fibropapillomas of domestic cattle were tested for papillomavirus using indirect immunofluorescence (if), peroxidase-antiperoxidase (pap), and negative-stain electron microscopic techniques. papillomavirus was consistently detected using rabbit antiserum against papillomavirus group-specific antigen in all mule deer fibromas and bovine fibropapillomas; only 16 of ... | 1985 | 2408523 |
| u1 small nuclear rna genes are subject to dosage compensation in mouse cells. | multiple copies of a gene that encodes human u1 small nuclear rna were introduced into mouse c127 cells with bovine papilloma virus as the vector. for some recombinant constructions, the human u1 gene copies were maintained extrachromosomally on the viral episome in an unrearranged fashion. the relative abundance of human and mouse u1 small nuclear rna varied from one cell line to another, but in some lines human u1 rna accounted for as much as one-third of the total u1. regardless of the level ... | 1985 | 2409601 |
| expression of a human u1 rna gene introduced into mouse cells via bovine papillomavirus dna vectors. | we introduced a gene for human u1 small nuclear rna, hu1-1, into mouse c127 cells via bovine papillomavirus (bpv) vectors. after transfection, up to 15% of the total u1 rna in transformed cells was encoded by the introduced human genes. high levels of expression of the human gene were observed when the recombinant viral dnas were maintained either as plasmids or after integration into high-molecular-weight dna. as few as 400 and 35 base pairs of 5' and 3' flanking region sequences, respectively, ... | 1985 | 2412107 |
| analysis of pp60c-src protein kinase activity in hamster embryo cells transformed by simian virus 40, human adenoviruses, and bovine papillomavirus 1. | we have examined the effect of dna tumor virus transformation of primary hamster embryo cells on the tyrosyl kinase activity of pp60c-src. our present study demonstrates that some clones of hamster embryo cells transformed by simian virus 40, adenovirus type 2, adenovirus type 12, or bovine papillomavirus 1 can possess elevated pp60c-src kinase activity when compared with normal hamster embryo cells. however, other clones of hamster embryo cells transformed by these same viruses were found to ha ... | 1986 | 2416954 |
| [papilloma viruses: group-specific antigens within lesions of the oral mucosa]. | the present study was undertaken with purpose to investigate the relationships between intraepithelial proliferations of malpighian mucosa and the presence of group specific papilloma virus antigens. the investigations allowing to give viral types or subtypes, the hybridization technics, are very heavy and not disponible in routine practice. the detection of widely distributed genus specific hpv antigen using pap immunohistochemical labeling in different lesions and their association with displa ... | 1986 | 2421394 |
| papillomaviruses and interferon. | papillomaviruses are infectious agents which cause benign tumours, or warts, of cutaneous, uterine cervical and laryngeal epithelia. these infections are very common, yet no uniformly effective therapy exists. current treatments do not selectively inhibit viral processes but destroy the infected epithelial cells. since interferons have antiviral effects in vivo and in vitro, it was hypothesized that they might be useful for treating papillomavirus-induced conditions. interferons have now been de ... | 1986 | 2424679 |
| in vitro methylation of bovine papillomavirus alters its ability to transform mouse cells. | bovine papillomavirus (bpv) was methylated in vitro at either the 29 hpaii sites, the 27 hhai sites, or both. methylation of the hpaii sites reduced transformation by the virus two- to sixfold, while methylation at hhai sites increased transformation two- to fourfold. dna methylated at both hpaii and hhai sites did not differ detectably from unmethylated dna in its efficiency of transformation. these results indicate that specific methylation sites, rather than the absolute level of methylated c ... | 1986 | 2431294 |
| 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 |
| replication of the bovine papillomavirus type 1 genome; antisense transcripts prevent episomal replication. | a subgenomic fragment, representing 69% of the bovine papillomavirus type 1 (bpv-1) genome, has the capacity to transform mouse c127 cells in vitro and to replicate episomally in these cells. in the present study we have cloned this bpv-1 fragment between two retrovirus-derived long terminal repeats (ltrs) in the two possible orientations. the constructs were designated pmr and pml. the pmr construct contained the bpv-1 genome in the same transcriptional orientation as that of the ltrs whereas t ... | 1986 | 2438189 |
| 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 |
| topographical and conformational epitopes of bovine papillomavirus type 1 defined by monoclonal antibodies. | monoclonal antibodies (mabs) were generated against sodium dodecyl sulfate-disrupted bovine papillomavirus type 1 (bpv-1). when screened by enzyme-linked immunosorbent assay (elisa) on intact and disrupted bpv-1, -2, and deer papillomavirus, three patterns of reactivity were defined: reactivity only with intact virus, with both intact and disrupted virus, and only with disrupted virus. on the basis of elisa results, the topographical location and requirement for conformation for immunoreactivity ... | 1987 | 2446044 |
| stable expression of recombinant factor viii molecules using a bovine papillomavirus vector. | the bleeding disorder in hemophilia a results from a deficiency or abnormality of factor viii (fviii), a member of the coagulation cascade. fviii is a large glycoprotein (approximately 350,000 daltons) that is activated by a series of proteolytic cleavages. during activation, a large internal domain (b domain) is removed, resulting in an active complex comprised of the amino and carboxyl subunits of the parental molecule. using a bovine papillomavirus expression vector system, we have establishe ... | 1987 | 2448100 |
| transcriptional regulation of the human papillomavirus-16 e6-e7 promoter by a keratinocyte-dependent enhancer, and by viral e2 trans-activator and repressor gene products: implications for cervical carcinogenesis. | the transcriptional promoter of the candidate e6-e7 transforming gene region of human papillomavirus (hpv)-16 (p97) was active in transiently transfected cervical carcinoma cells when linked to the hsv-1 tk or bacterial cat genes. sequences 5' to p97 contain a short enhancer element responding to cellular factor(s) in uninfected human foreskin keratinocytes and in cervical carcinoma cells, but not in human or animal fibroblasts. the e2 trans-activator products of hpv-16 or of the related bovine ... | 1987 | 2448139 |
| 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 |
| human antibodies react with an epitope of the human papillomavirus type 6b l1 open reading frame which is distinct from the type-common epitope. | recombinant proteins encoded by the human papillomavirus type 6b (hpv6b) l1 open reading frame react with sera from patients with condylomata acuminata and also react with rabbit antiserum raised against sodium dodecyl sulfate-disrupted bovine papillomavirus type 1 (bpv1) virions. to map the immunoreactive epitopes, a series of procaryotic expression plasmids was made which contained a nested set of 3' to 5' deletions in the hpv6b l1 open reading frame. the deleted plasmids expressed a set of ca ... | 1989 | 2463384 |
| demonstration of in vitro synthesis of human papilloma viral proteins from hand and foot warts. | hpv particles purified from [35s]-methionine labeled and unlabeled halves of single hand and foot warts have been fractionated into empty, light full, and heavy full particles by buoyant density gradient centrifugation, and their proteins analyzed by two-dimensional gel electrophoresis (ief and nephge) and visualized by either fluorography or silver staining. the l1 coat protein (54 kd) was found in trace amounts in unmodified and slightly modified forms in the labeled empty and light full parti ... | 1989 | 2470829 |
| expression in escherichia coli of seven dna fragments comprising the complete l1 and l2 open reading frames of human papillomavirus type 6b and localization of the 'common antigen' region. | molecular cloning was used to express human papillomavirus type 6b (hpv-6b) antigens in escherichia coli. seven genomic dna fragments of hpv-6b which together comprise the complete l1 and l2 open reading frames, known to code for capsid proteins, were cloned and expressed in e. coli as both beta-galactosidase and trpe fusion proteins. western blots of hpv-6b beta-galactosidase fusion proteins using 'genus-specific' antisera produced by immunization of rabbits with disrupted bovine papillomavirus ... | 1989 | 2471790 |
| identification of l2 open reading frame gene products of bovine papillomavirus type 1 using monoclonal antibodies. | four hybridoma cell lines producing monoclonal antibodies (mabs) to bovine papillomavirus type 1 (bpv-1) l2 open reading frame (orf) gene products have been established from mice immunized with a bpv-1 l2-beta-galactosidase fusion protein. hybridomas were selected and cloned (from over 700 hybridomas) on the basis of specific reactivity of supernatant fluids with bpv-1 l2 epitopes on disrupted bpv-1 particles and l2-beta-galactosidase fusion proteins by elisa and western blotting, and with aceto ... | 1989 | 2471804 |
| the human papillomavirus type 18 (hpv18) e2 gene product is a repressor of the hpv18 regulatory region in human keratinocytes. | the human papillomavirus type 18 (hpv18) long control region (lcr) harbors transcriptional promoter and enhancer elements. recombinant plasmids bearing all or part of the hpv18 lcr cloned in enhancer or promoter configuration upstream of the chloramphenicol acetyltransferase (cat) gene were transfected into human fibroblasts and keratinocytes. although the hpv18 enhancer can function in the absence of e2 gene products in both fibroblasts and keratinocytes, the promoter activity of the hpv18 lcr ... | 1989 | 2476572 |
| tumorigenicity, invasiveness and metastatic capability of fr3t3 rat cells before and after transfection with bovine papilloma virus type 1 dna. | fischer rat fr3t3 cells were tested for tumorigenicity, invasive and metastatic capabilities before and after transfection, either with the entire bovine papilloma virus type 1 (bpv-1) genome or with a plasmid (pv69) containing a 69 per cent bam h1-hind iii fragment of the bpv-1 genome as well as bacterial sequences. cell lines were grouped as parental, pv69-transfectants, bpv-1 transfectants, in vitro derivatives, and in vivo derivatives. the tumorigenic, invasive and metastatic capabilities of ... | 1989 | 2535681 |
| open reading frames e6 and e7 of bovine papillomavirus type 1 are both required for full transformation of mouse c127 cells. | a series of mutations in open reading frames (orfs) e6 and e7 of bovine papillomavirus type 1 (bpv1) was constructed to analyze the roles of these orfs in transformation of mouse c127 cells. the mutations were designed to prevent synthesis of specific proteins encoded by these genes. none of the mutations caused a decrease in the focus-forming activity of the full-length viral genome or in the ability of the viral dna to replicate as a high-copy-number plasmid. analysis of these mutants in the a ... | 1989 | 2535732 |
| complete nucleotide sequence of the chromosomal gene for human il-4 and its expression. | we have isolated a chromosomal dna segment of the human il-4 gene based on homology with a human il-4 cdna sequence and determined its complete nucleotide sequence. the human il-4 gene, which occurs as a single copy in the haploid genome, is mapped on chromosome 5. it is composed of four exons and three introns and is approximately 10 kilobase pairs in size. 5'-flanking regions of human and mouse il-4 genes share about 85% homology extending more than 500 base pairs upstream of a "tata" like seq ... | 1989 | 2535858 |
| e2 polypeptides encoded by bovine papillomavirus type 1 form dimers through the common carboxyl-terminal domain: transactivation is mediated by the conserved amino-terminal domain. | the e2 open reading frame (orf) of bovine papillomavirus type 1 (bpv-1) encodes positive- and negative-acting factors that regulate viral gene expression. the full-length orf encodes a transactivator, and two transcriptional repressors are expressed from the 3' half of the orf. previous analysis has shown that a conserved c-terminal region of 101 amino acids, which is shared by e2 transactivator and repressor proteins, contains the specific dna binding activity. further analysis of the e2 transa ... | 1989 | 2536165 |
| papillomavirus polypeptides e6 and e7 are zinc-binding proteins. | papillomavirus proteins e6 and e7 have cys-x-x-cys repeats which have been suggested to mediate zinc binding. we have developed a modification of an assay that detects zinc binding to proteins immobilized on filters. using well-characterized metalloproteins, we show that, under reducing conditions, this assay distinguishes proteins that coordinate zinc through cysteine residues from those that bind the metal through other amino acids. under these conditions, e6 and e7 polypeptides of human papil ... | 1989 | 2536841 |
| the bovine papillomavirus type 1 transcriptional activator e2 protein binds to its dna recognition sequence as a dimer. | the transcriptional trans-activator e2 protein from bovine papillomavirus type 1 has been shown to bind to the dna consensus sequence accn6ggt. we have produced the dna-binding domain of the e2 protein as a recombinant protein in escherichia coli. the e2 dna-binding domain was purified as two different molecular weight forms. using these purified proteins, we show that two molecules of the e2 protein bind to a single dna consensus binding site. | 1989 | 2538035 |
| bovine papillomavirus type 1 encodes two forms of a transcriptional repressor: structural and functional analysis of new viral cdnas. | genetic and biochemical evidence has established that the e2 open reading frame (orf) of bovine papillomavirus type 1 encodes at least two different site-specific dna-binding proteins, one which activates and the other which represses expression from a viral promoter (p. f. lambert, b. a. spalholz, and p. m. howley, cell 50:69-78, 1987). we have obtained data which show that a second form of the repressor gene is expressed in transformed cells harboring stable viral plasmids. the structural deta ... | 1989 | 2538655 |
| identification of bovine papillomavirus e1 mutants with increased transforming and transcriptional activity. | the e1 open reading frame of bovine papillomavirus type 1 (bpv) has been shown previously to encode trans-acting functions, m and r, that are involved in extrachromosomal replication of the viral genome. we have determined that several e1 mutants mapping in both the m and r regions and a single mutant of the upstream regulatory region have a higher transforming activity on mouse c127 cells than the wild-type genome does. a representative mutant in m, a mutant in r, and the upstream regulatory re ... | 1989 | 2538656 |
| evidence for multiple vegetative dna replication origins and alternative replication mechanisms of bovine papillomavirus type 1. | by following up the chance detection in the electron microscope of a dna replication intermediate within a preparation of bovine papillomavirus (bpv-1) dna isolated from purified virus particles, information was obtained about the mechanism of bpv-1 genome replication during the final stages of virus multiplication in naturally infected bovine wart tissue. the structure of viral replication intermediates was investigated by electron microscopic analysis of viral dna linearized by digestion with ... | 1989 | 2539483 |
| loss of bovine papillomavirus dna replication control in growth-arrested transformed cells. | the bovine papillomavirus type 1 (bpv-1) genome replicates as a plasmid within the nuclei of bpv-1-transformed murine c127 cells at a constant multiple copy number, and spontaneous amplification of the viral dna is rarely observed. we report here that a mutant bpv-1 plasmid within a contact-inhibited c127 cell line replicated as a stable multicopy plasmid in exponentially growing cells but amplified to a high level in confluent cell culture. in situ hybridization analysis revealed that most of t ... | 1989 | 2539513 |
| mutational analysis of bovine papillomavirus e6 gene. | the bovine papillomavirus e6 gene can independently transform mouse c127 cells. to characterize e6 in greater detail, we created 16 site-directed mutations in e6, including substitution mutations in the cysteine codons of the four cys-x-x-cys motifs that are conserved in all papillomavirus e6 proteins. proteins mutated in six of the seven cysteines tested, as well as those lacking the nonconserved c-terminus, were stable in transfected cells but were unable to induce morphological transformation ... | 1989 | 2539522 |
| efficient activation of transcription in yeast by the bpv1 e2 protein. | the full-length gene product encoded by the e2 open reading frame (orf) of bovine papillomavirus type 1 (bpv1) is a transcriptional transactivator. it is believed to mediate its effect on the bpv1 long control region (lcr) by binding to motifs with the consensus sequence accn6ggt. the minimal functional cis active site, called the e2 response element (e2re), in mammalian cells comprises two copies of this motif. here we have shown that e2 can function in saccharomyces cerevisiae by placing an e2 ... | 1989 | 2539584 |
| selective enhancement of bovine papillomavirus type 1 dna replication in xenopus laevis eggs by the e6 gene product. | genetic analyses of bovine papillomavirus type 1 (bpv-1) dna in transformed mammalian cells have indicated that the e6 gene product is essential for the establishment and maintenance of a high plasmid copy number. in order to analyze the direct effect of the e6 protein on the replication of a bpv-1-derived plasmid, a cdna containing the bpv-1 e6 open reading frame was subcloned into an sp6 vector for the in vitro synthesis of the corresponding mrna. the sp6 e6 mrna was injected into xenopus laev ... | 1989 | 2540419 |
| transcriptional regulation by estrogen of episomal prolactin gene regulatory elements. | as a first step in defining the role of chromatin structure in steroid-regulated gene transcription, we have established a steroid-responsive minichromosome system that contains the 5' upstream regulatory region of the rat prl gene (prl) from -10 to -1960-basepairs fused to the antibiotic resistance gene, tn5. the hybrid gene was inserted into a bovine papilloma virus (bpv) vector and then transfected into gh3 cells. southern analysis of total genomic dna revealed that the prl-tn5-bpv dna existe ... | 1989 | 2540428 |
| amplification of specific dna sequences in c127 mouse cells transformed by bovine papillomavirus type 4. | a rearranged bovine papillomavirus type 4 dna fragment, present in a line of transformed c127 cells, was molecularly cloned into lambda gt 10. the rearranged viral fragment was found to consist of two separate sequences of 3.8 kb each. clone a comprised 3.3 kb of host dna linked to 0.5 kb of bpv-4 dna. clone b consisted of 2.2 kb of host dna linked to 1.5 kb of bpv-4 dna. the ab locus was found to be amplified and rearranged in a number of different bpv-4 transformed c127 cell lines, irrespectiv ... | 1989 | 2541389 |
| successive steps in the process of immortalization identified by transfer of separate bovine papillomavirus genes into rat fibroblasts. | transfer of neor and bovine papillomavirus type 1 (bpv1) dna into rat embryo fibroblasts led to colony formation in g418-containing medium, with no detectable background in controls with neor dna alone. more than 50% of the drug-resistant clones could be further propagated in culture. the genetic functions of bpv1 involved in colony formation and in long-term immortalization were investigated by both translation termination mutations in the full-length genome, which inactivate individual open re ... | 1989 | 2541438 |
| genetic analysis of crpv pathogenesis: the l1 open reading frame is dispensable for cellular transformation but is required for papilloma formation. | genetic studies to elucidate the role of papillomaviruses in the development and progression of tumors have been severely hampered because the viruses cannot be grown in tissue culture and therefore mutants are not available. we have employed recombinant dna for papilloma induction to identify essential sequences involved in papillomavirus pathogenesis. here, we demonstrated that deleting most of the open reading frame (orf) l2 did not affect the potential of viral cottontail rabbit papillomavir ... | 1989 | 2541552 |
| the e5 oncoprotein of bovine papillomavirus is oriented asymmetrically in golgi and plasma membranes. | the e5 oncoprotein of bpv-1 is a 44 amino acid, hydrophobic polypeptide which is present in membrane fractions of transformed cell homogenates. to define the specific cellular membrane compartments with which e5 associates, immunofluorescence and immunoelectron microscopy were performed using an affinity-purified antibody specific for the e5 carboxyl-terminus. two cell systems which overexpressed the e5 protein were analyzed: (1) balb/c 3t3 mouse cells transformed by a bpv-1 cdna expressing the ... | 1989 | 2541554 |
| expression of hepatitis b virus surface antigen containing the pre-s region in mammalian cell culture system. | the surface antigen of hepatitis b virus (hbv) has been expressed in a mouse cell line using metallothionein-bovine papilloma virus vectors. four different recombinant plasmids were used and it was found that the expression level varies significantly from one plasmid to another. removing the hbv polyadenylation signal from the plasmid drastically reduced the expression level. providing even a heterologous polyadenylation signal improved the expression level from the reduced one by at least tenfo ... | 1989 | 2541576 |
| specific recognition nucleotides and their dna context determine the affinity of e2 protein for 17 binding sites in the bpv-1 genome. | the dna context of nucleotides that a protein recognizes can influence the strength of the protein-dna interaction. moreover, in prokaryotes, understanding the quantitative differences in binding affinities that result in part from the dna context is often important in describing regulatory mechanisms. nevertheless, these issues have not been a major focus yet for the investigation of protein-dna interactions in eukaryotes. in this study, we explored the binding specificity and the range of affi ... | 1989 | 2542129 |
| genetic assignment of multiple e2 gene products in bovine papillomavirus-transformed cells. | the e2 open reading frame of bovine papillomavirus type 1 has been shown genetically to encode at least three transcriptional regulatory factors, and three e2 specific proteins have been recently identified in virally transformed rodent cells. in this study, the genes encoding these e2 specific proteins have been determined. the 48-kilodalton (kda) protein was identified as the product of a full-length e2 open reading frame cdna, which confirmed that this polypeptide is the e2 transactivator. th ... | 1989 | 2542621 |
| cell-heritable stages of tumor progression in transgenic mice harboring the bovine papillomavirus type 1 genome. | tumorigenesis of dermal fibroblasts in a line of transgenic mice carrying the bpv-1 genome was found to involve distinct proliferative stages. cell cultures derived from normal skin, from benign proliferative fibromatoses, and from malignant fibrosarcomas each evidenced distinguishable, cell-heritable characteristics. the latent viral genome was transcriptionally inactive in normal-appearing skin and was activated in the dermal fibromatoses. fibrosarcoma cells grew continuously in culture, forme ... | 1989 | 2542769 |
| multiple cooperative interactions constrain bpv-1 e2 dependent activation of transcription. | transcription directed by the bpv-1 long control region (lcr) is conditional upon activation by the virally encoded e2 protein. within the 1.0 kb lcr there are five separate regions, a to e, that contain e2 responsive enhancers. the smallest functional region, a, is only 38 bp and contains two copies of the consensus sequence acc(n)6ggt that is known to function as an e2 binding site in vitro. we show that a pair of these constitutes a minimal functional e2 responsive enhancer element but that t ... | 1989 | 2542891 |
| expression of epstein-barr virus membrane antigen gp340/220 in mouse fibroblasts using a bovine papillomavirus vector. | epstein-barr virus (ebv) membrane antigen glycoproteins gp340 and gp220 are encoded by a single gene. we have inserted this gene into a bovine papillomavirus (bpv) vector and expressed gp340/220 in mammalian cells under the control of the mouse metallothionein promoter. the proteins produced were of similar mr, showed similar antigenic specificity and were transported to the same subcellular location as the authentic gp340/220. the inclusion of heavy metal ions in the medium had no effect on the ... | 1989 | 2543757 |
| the effect of bovine herpesvirus type 1 glycoproteins gi and giii on herpesvirus infections. | we expressed the bovine herpesvirus type 1 (bhv-1) glycoproteins, gi and giii, in bovine cells using a bovine papillomavirus vector. the proteins expressed by these cells had the same mr as the native bhv-1 proteins and monoclonal antibodies detected no differences in their antigenic structure. cells expressing gi were infected with either bhv-1 or herpes simplex virus type 1 (hsv-1). the number of plaques in gi-expressing cells was similar to that seen with normal fibroblasts infected with bhv- ... | 1989 | 2543789 |
| characterization of bovine papillomavirus type 1-transformed clones which show distinct transformed phenotypes. | seventeen independent cell clones were isolated from c127 cells transformed by bovine papillomavirus type 1 (bpv-1). transformants showed differing degrees of expression of the transformed phenotype as monitored by saturation density, doubling time, growth in medium with a low serum concentration and colony-forming efficiency in soft agar. the degree of expression of the transformed phenotype did not correlate with either the bpv-1 copy number or levels of bpv-1-specific rna in the transformed c ... | 1989 | 2543792 |
| specific chromosomal abnormalities characterize fibrosarcomas of bovine papillomavirus type 1 transgenic mice. | in the bpv1.69 line of transgenic mice, the bovine papillomavirus type 1 genome elicits both benign dermal fibroblastic proliferation (fibromatoses) and malignant fibrosarcomas. because these lesions arise only with time, nonviral factors appear to be involved. we have karyotyped several primary tumors as well as a series of low-passage cell lines derived both from fibromatoses and from fibrosarcomas. the fibrosarcomas, but not the preneoplastic fibromatoses, show consistent abnormalities of one ... | 1989 | 2544888 |
| identification and characterization of the bpv-2 l2 protein. | the bovine papilloma virus type 2 (bpv-2) l2 open reading frame was cloned into a lambda pl promoter expression vector. this plasmid was shown to express a fusion protein which constituted 75% of the bpv-2 l2 orf linked to the first 13 n-terminal amino acids of the lambda cll gene product. antisera generated against this fusion protein were used to identify the l2 gene product as a 64,000-da protein in bpv-2 virions. western blot analysis demonstrated that the l2 viral protein was present in ful ... | 1989 | 2545035 |
| infectious papillomavirus in the vapor of warts treated with carbon dioxide laser or electrocoagulation: detection and protection. | papillomavirus dna has been reported recently in the vapor (smoke plume) derived from warts treated with carbon dioxide laser; this raises concerns for operator safety. we therefore have studied a group of human and bovine warts to define further the potential risk of wart therapy and to test whether a surgical mask could reduce exposure. half of each wart was treated with carbon dioxide laser and the other half with electrocoagulation. the vapor produced by each form of therapy was collected wi ... | 1989 | 2545749 |
| transcriptional termination between bovine papillomavirus type 1 (bpv-1) early and late polyadenylation sites blocks late transcription in bpv-1-transformed cells. | bovine papillomavirus type 1 (bpv-1) is a small dna tumor virus which induces fibropapillomas in cattle and transforms rodent cells in culture. transcripts are derived from a single strand of the circular viral genome, which has multiple promoters and two polyadenylation sites. in the transformed cell, the first (early) polyadenylation site is utilized exclusively and, therefore, only the early region is expressed. transcription of the late genes, which requires use of the second (late) polyaden ... | 1989 | 2545923 |
| dual loci of dna bending in the bovine papillomavirus upstream regulatory region. | recombinant clones containing all or portions of the bovine papillomavirus (bpv) upstream regulatory region (urr) were constructed. when analyzed by polyacrylamide gel electrophoresis, the cloned urr sequences exhibited electrophoretic properties characteristic of dna containing bend sites. two distinct bend centers were identified, mapping to approximately 7477 and 7790 respectively on the bpv genome. no other loci of static dna bending were detected in the urr region of the bpv genome. | 1989 | 2546330 |
| stably expressed fipv peplomer protein induces cell fusion and elicits neutralizing antibodies in mice. | we have established bovine papilloma virus (bpv)-transformed mouse c127 cell lines that synthesize the peplomer protein of the feline infectious peritonitis virus (fipv) strain 79-1146. for this purpose, a new cassette expression vector phsl, which carries the drosophila hsp70 promotor and the polyadenylation signal of the moloney murine leukemia virus long terminal repeat, was constructed. cocultivation of the bpv-transformed cell lines with fipv-permissive feline fcwf-d cells resulted in polyk ... | 1989 | 2548329 |
| bovine papilloma virus encoded e2 protein activates lymphokine genes through dna elements, distinct from the consensus motif, in the long control region of its own genome. | activation of t cells by antigen, lectin or a combination of phorbol ester (pma) and calcium ionophore (a23187) leads to the induction of a set of lymphokine genes. transfection of a human t cell leukemia cell line, jurkat, or an african green monkey kidney cell line, cv1, with a cdna encoding e2 protein, a trans-activator of bovine papilloma virus type 1, results in activation of interleukin 2 (il-2), interleukin 3 (il-3) and granulocyte/macrophage colony-stimulating factor (gm-csf) genes in a ... | 1989 | 2548843 |
| papillomavirus-associated inductions of cellular proteins in mouse c127 cells: correlation with the presence of open reading frame e2. | bovine papillomavirus type 1 (bpv-1) readily transforms mouse c127 cells, conferring the ability to grow in soft agar and to form tumors in athymic (nu/nu) mice. electrophoresis of total cellular proteins from these bpv-transformed lines on ultra-high resolution, giant two-dimensional gels displays the presence of novel, papillomavirus-related protein phenotypes. analysis of the established bpv-1-transformed c127 cell lines, id13 and id14, reveals a set of six proteins which are either absent or ... | 1989 | 2549708 |
| the adeno-associated virus rep78 gene inhibits cellular transformation induced by bovine papillomavirus. | adeno-associated virus type 2 (aav) is a helper dependent parvovirus which can inhibit the oncogenic and transforming potential of its helper viruses: adenoviruses (ad) and herpesviruses. here we have assayed aav's ability to inhibit cellular transformation induced by bovine papillomavirus type 1 (bpv-1), a member of another family of dna viruses. aav was able to markedly inhibit bpv-1-induced transformation of contact-inhibited murine fibroblasts either by infection with virus particles or by d ... | 1989 | 2549714 |
| amplification of bovine papillomavirus dna by n-methyl-n'-nitro-n-nitrosoguanidine, ultraviolet irradiation, or infection with herpes simplex virus. | treatment with n-methyl-n'-nitro-n-nitrosoguanidine (mnng) or irradiation with ultraviolet light (uv254 nm) induces amplification of integrated as well as episomal sequences of bovine papillomavirus (bpv) type 1 dna in bpv-1-transformed mouse c127 cells (i.e., id13 cells). this is shown by filter in situ hybridization and southern blot analysis of cellular dna. similarly, infection of id13 cells with herpes simplex virus (hsv) type 1 which has been shown to be mutagenic for host cell dna leads t ... | 1989 | 2549724 |
| animal virus dna replication. | | 1989 | 2549858 |
| trans activation by the bovine papillomavirus e2 protein in saccharomyces cerevisiae. | the papillomavirus e2 protein functions as an enhancer-binding factor to promote transcription in mammalian cells. we found that one copy of the e2 binding site acted as an e2 protein-dependent upstream activating sequence in saccharomyces cerevisiae. additional copies of the binding motif further augmented transcription. these results imply that the e2 protein functionally interacts with highly conserved transcriptional elements. | 1989 | 2550673 |
| independent glucocorticoid induction and repression of two contiguous responsive genes. | specific dna sequence elements which contain binding sites for the glucocorticoid receptor mediate the action of glucocorticoid hormones on gene transcription. in glucocorticoid-inducible genes, these glucocorticoid-responsive elements behave as hormone-inducible enhancers of transcription. we have taken advantage of the bovine papillomavirus (bpv) system to test the stringency of glucocorticoid regulation of transcription. bpv episomes were constructed to contain two hormone-regulated transcrip ... | 1989 | 2550796 |
| the bovine papillomavirus e5 transforming protein can stimulate the transforming activity of egf and csf-1 receptors. | the bovine papillomavirus e5 transforming gene encodes a 44 amino acid protein product that is localized to cytoplasmic membranes, including the plasma membrane. we now report that e5 can cooperate with human egf receptors and with human csf-1 receptors to induce cellular transformation of nih 3t3 cells. cooperation occurred in the absence of receptor stimulation by ligand, and it was further augmented by treatment with ligand. cooperation was not seen between e5 and either c-fes or c-src. the c ... | 1989 | 2551505 |
| structure, activity, and regulation of the bovine papillomavirus e5 gene and its transforming protein product. | | 1989 | 2551579 |
| transforming activity of a 16-amino-acid segment of the bovine papillomavirus e5 protein linked to random sequences of hydrophobic amino acids. | the 44-amino-acid e5 protein of bovine papillomavirus type 1 is the smallest transforming protein yet described. previous results from our laboratory indicate that a hydrophobic core and specific carboxyl-terminal amino acids are required for the e5 protein to exert its transforming function. in this study, additional substitution mutations were generated in the e5 gene to determine the minimal amino acid sequence requirements for focus formation in mouse c127 cells. in most cases examined, subs ... | 1989 | 2552136 |
| mutational analysis of bovine papillomavirus type 1 e5 peptide domains involved in induction of cellular dna synthesis. | early gene e5 of bovine papillomavirus type 1 encodes a 44-amino-acid protein whose expression can transform immortalized mouse cell lines. we have previously reported that a chemically synthesized e5 peptide functions to induce cellular dna synthesis upon microinjection into growth-arrested mouse cells. we further defined the two e5 domains essential for the full dna synthesis induction activity by the analysis of e5 deletion and amino acid substitution mutant peptides. the first domain is the ... | 1989 | 2552177 |
| nutritional requirements of papillomavirus-transformed mouse cells and an uninfected parent line in serum-free culture. | a serum-free culture system was used to compare the nutritional requirements of mouse mammary cells transformed by bovine papillomavirus type 1 (id13 cells) and the uninfected parent line (c127 cells). the serum-free, chemically defined medium used for this study was an mcdb 151-based medium (mcdb 151+s+i), supplemented with epidermal growth factor, transferrin, hydrocortisone, ethanolamine, phosphoethanolamine, retinoic acid, trace metals, and insulin. proliferation of either cell type in serum ... | 1989 | 2553658 |
| the e2 trans-activating protein of bovine papillomavirus type 1 (bpv1) is serine-phosphorylated in vivo. | the e2 open reading frame of bovine papillomavirus 1 (bpv1) encodes both positive and negative transcriptional regulatory factors. the full-length e2 gene polypeptide is a strong transcriptional transactivator that acts on enhancers within the papillomavirus long control region (lcr), and two shorter e2 proteins function as transcription repressors. a vaccinia recombinant virus harboring the full length e2 coding sequence of bpv1 directs the synthesis of a 48 kd phosphoprotein with specific dna ... | 1989 | 2554235 |
| induction of virus-producing tumours in athymic nude mice by bovine papillomavirus type 4. | bovine papillomavirus type 4 (bpv-4), the causative agent of alimentary papillomatosis, has been used to infect, in vitro, fragments of palatine mucosa from late term bovine fetuses. these small explants were placed beneath the renal capsule of athymic nude mice where they grew to produce, at first, squamous epithelial cysts containing bpv-4 genomic dna and, later, papillomas which were morphologically identical to those of cattle and which contained large amounts of replicating virus. the possi ... | 1989 | 2554558 |
| suppression of focus formation by bovine papillomavirus-transformed cells by contact with non-transformed cells: involvement of sugar(s) and phosphorylation. | focus formation by bovine papilloma virus-transformed c127 cells was inhibited by direct contact with non-transformed c127 cells. the suppressive capacity of c127 cells was abolished by introduction of the neomycin resistance gene (neor) but not by that of the hygromycin resistance gene (hygrr). though both genes code for phosphotransferase which inactivates the aminoglycoside antibiotics, their substrates are different, i.e., there is no cross-resistance between them. as the neomycin phosphotra ... | 1989 | 2555308 |
| inducible expression of encephalomyocarditis virus 3c protease activity in stably transformed mouse cell lines. | an inducible expression vector system has been developed to facilitate the study of the effects of individual virus gene products on cell function. the vector utilizes the mouse metallothionein promoter carried on the bovine papillomavirus genome. conditions which optimize the induced expression of open reading frames inserted downstream from the mouse metallothionein promoter have recently been described. in this communication we describe the use of this system to clone and express the encephal ... | 1989 | 2555538 |
| phosphorylation sites of the e2 transcriptional regulatory proteins of bovine papillomavirus type 1. | the e2 open reading frame of bovine papillomavirus type 1 (bpv-1) encodes three transcriptional regulatory proteins. the full-length open reading frame encodes a protein of 410 amino acids which functions as a transcriptional transactivator. two transcriptional repressor proteins, e2-tr and e8/e2, contain the c-terminal 249 and 204 amino acids, respectively. we have expressed both the full-length e2 protein and the e2-tr repressor protein in insect cells, by using recombinant baculoviruses, and ... | 1989 | 2555544 |
| genetic evidence that acute morphologic transformation, induction of cellular dna synthesis, and focus formation are mediated by a single activity of the bovine papillomavirus e5 protein. | the bovine papillomavirus (bpv) type 1 e5 gene encodes a 44-amino-acid protein that can stably transform cultured rodent cells when expressed in the absence of all other viral genes. we have previously constructed a bpv-simian virus 40 recombinant virus (pava-1) which efficiently expresses the bpv type 1 e5 gene in infected cells (j. settleman and d. dimaio, proc. natl. acad. sci. usa 85:9007-9011, 1988). within 48 h of pava-1 infection, the vast majority of mouse c127 cells underwent a dramatic ... | 1989 | 2555701 |
| purification and dna-binding properties of human papillomavirus type 16 e6 protein expressed in escherichia coli. | unfused human papillomavirus type 16 (hpv 16) e6 protein was expressed in escherichia coli using a lambda pl promoter system. the protein was isolated from the cells as inclusion bodies, extracted by 6 m guanidine-hcl, and purified by chromatography. the purified protein had high affinity to dna and was demonstrated for the first time to bind to a specific sequence within the long control region of hpv 16. | 1989 | 2556128 |
| complex formation of human papillomavirus e7 proteins with the retinoblastoma tumor suppressor gene product. | the e7 proteins encoded by the human papillomaviruses (hpvs) associated with anogenital lesions share significant amino acid sequence homology. the e7 proteins of these different hpvs were assessed for their ability to form complexes with the retinoblastoma tumor suppressor gene product (p105-rb). similar to the e7 protein of hpv-16, the e7 proteins of hpv-18, hbv-6b and hpv-11 were found to associate with p105-rb in vitro. the e7 proteins of hpv types associated with a high risk of malignant pr ... | 1989 | 2556261 |
| injection of xenopus eggs before activation, achieved by control of extracellular factors, improves plasmid dna replication after activation. | injection of molecular probes into unfertilized xenopus eggs requires suppression of activation. but the unfertilized egg is poised for activity, and pricking, like sperm penetration, triggers the start of the first cell cycle. methods of suppressing activation generally rely on introduction of drugs into the cell, but some of these techniques are irreversible. i report here that injection without activation can also be accomplished by simply limiting extracellular free ca2+ to 1-2 microm. the s ... | 1989 | 2559091 |
| [using bpv transforming foci as selective markers to express hbsag]. | we constructed a plasmid pbmthbr2 containing mouse mt promoter, entire hbsag gene (pres and s gene), splicing signal from sv40 and complete bpv genome. using calcium phosphate precipitation technique to transform c127 cells and using bpv transforming foci as selective markers, we obtained transformed cell clones. the experiment shows that 57% of the cloned cell lines can secrete hbsag continuously. | 1989 | 2561512 |
| bovine papillomavirus type i induces resistance to ca+(+)-induced terminal differentiation in murine keratinocytes. | bovine papillomavirus type 1 (bpv-1) was expressed in established mouse balb/mk epidermal keratinocytes. in each of the transfected cell lines, dna synthesis was stimulated by epidermal growth factor (egf) and inhibited by type beta transforming growth factor to an extent similar to that in parental cells. in contrast, the bpv-1-transfectants were resistant to the induction of terminal differentiation by extracellular ca(+)+. first, bpv transfectants continued to respond to egf in the presence o ... | 1989 | 2561735 |
| tumorigenic latency and separable stages during fibrosarcoma development in transgenic mice carrying papillomavirus genomes. | transgenic mice have been established carrying the genomes of bovine papillomavirus type 1 (bpv-1), and human papillomaviruses types 5 and 18. transcriptional dormancy is characteristic of all three viral genomes in transgenic mouse lines maintained for 2-4 years. only bpv-1, which induces both dermal and epidermal pathology in its natural host, has been found to elicit abnormalities when carried in transgenic mice. the bpv-1 genome acts in these mice as a tissue specific oncogene, in that it el ... | 1989 | 2562186 |
| structure and expression of two human metallothionein-i isoform genes and a related pseudogene. | three members of the human metallothionein-i gene family have been cloned and characterized. two of the genes encode closely related but distinct metallothionein-i subtypes. both of these genes are functional as shown by their transcription in cultured hepatoblastoma cells and by their ability to render transfected cells resistant to cadmium toxicity. the cotranscription of these nonallelic genes shows that the previously observed microheterogeneity of metallothionein-i protein preparations is d ... | 1985 | 2581970 |
| promoting activity of betel quid ingredients and their inhibition by retinol. | ingredients of betel quids, which have been linked to the high incidence of precancerous oral lesions and oral cancers, were examined for their promoting activity. aqueous extracts were tested using the bovine papillomavirus (bpv) dna transformation assay, which consists of cultured c3h/10t1/2 cells transfected with the plasmid pdpbv-1 as targets, and the frequency of transformed foci as endpoints. areca nut extracts enhanced the formation of bpv dna-induced transformed foci approximately tenfol ... | 1989 | 2713825 |
| mouse cell lines that use heat shock promoters to regulate the expression of tissue plasminogen activator. | the promoters from drosophila and human 70,000-dalton heat shock protein (hsp70) genes were linked to human tissue plasminogen activator (tpa) cdna. mouse c127 cells were transformed with bovine papilloma virus (bpv) vectors carrying the hybrid hsp70/tpa genes. stable bpv-transformed cell lines were selected and analyzed for tpa expression before and after heat shock. in most cell lines, there was a low level of tpa production even in the absence of heat shock or other obvious stress. after heat ... | 1987 | 2820678 |
| isolation and characterization of minichromosome particles that contain a glucocorticoid-modulated promoter. | a procedure for the enrichment of minichromosomes, composed of bovine papilloma virus and the long terminal repeat element of the mouse mammary tumor virus (mtv), from isolated nuclei is described. up to 60% of the minichromosomes were extracted as nucleoprotein particles. these particles sediment in sucrose gradients as 160s complexes. hormone-labeled glucocorticoid receptor co-purifies with these complexes in a specific fashion. between four and six molecules of receptor are bound per minichro ... | 1987 | 2821487 |
| optimizing gene expression in bpv-transformed cells: effects of cell type on enhancer/promoter interaction. | we have compared several combinations of enhancers and promoters in expressing the chloramphenicol acetyl transferase gene in transient assays, in mouse c127, the most widely used host cell for the bovine papilloma virus (bpv) expression vector. of the various combinations tested, the unit comprised of the sv40 enhancer and adenovirus type 2 major late promoter (mlp) was the most active in bpv transformed c127 cells. we further demonstrate that untransformed and bpv transformed c127 cells respon ... | 1987 | 2821493 |
| genetic and biochemical definition of the bovine papillomavirus e5 transforming protein. | mutations surrounding the first methionine codon of the e5 transforming gene of bovine papillomavirus (type 1) were analyzed for their effect on cellular transformation and on the synthesis of the 7-kd e5 polypeptide. frameshift mutations upstream of this methionine codon (bp 3879) affect neither transforming activity nor the ability to synthesize full-size e5 protein. in contrast, frameshift mutations distal to this position result in the inhibition of cell transformation and prevent synthesis ... | 1987 | 2822390 |
| skin cancer and papillomaviruses in cattle. | we examined proliferative lesions on the sun-exposed, unpigmented skin of 13 cattle. ages of animals at first examination ranged from 4 to 15 years, and 4 were observed for from one to 3 years, during which time progression to malignancy occurred in 2 of them. early lesions consisted of keratin scales and horns; histology showed underlying acanthosis and hyperkeratosis. advanced lesions were either squamous cell carcinomas or basaloid tumours with sebaceous and/or squamous differentiation; some ... | 1987 | 2822781 |