ethidium bromide inhibits appearance of closed circular viral dna and integration of virus-specific dna in duck cells infected by avian sarcoma virus.the dna of avian sarcoma virus assumes a closed circular configuration before integration into the host cell chromosomal dna. ethidium bromide reduces the formation of superhelical viral dna and concurrently blocks integration of the viral genome. inhibition of integration of viral dna results in the inhibition of virus replication.1975163973
high spontaneous mutation rate of an avian sarcoma virus.three genetically distinct types of chicken sarcoma virus bratislava 77 (b77 virus) differing in their ability to infect duck cells were identified. b77 virus type i does not infect duck cells; b77 virus type ii has a low efficiency of infection of duck cells; and b77 virus type iii has a high efficiency of infection of duck cells. b77 viruses type i and iii are produced by spontaneous mutation during the growth of b77 virus type ii in chicken cells. the spontaneous mutation of b77 virus type ii ...1975173893
expression of tumor-specific surface antigens on cells infected with temperature-sensitive mutants of avian sarcoma virus. 1975166486
diamine oxidase and polyamine oxidase activities in normal and transformed cells.1. the activity of diamine oxidase (ec in normal rat kidney cells and in normal rat kidney cells transformed by avian sarcoma virus (b77 strain) growing in tissue culture varies with the stage of growth. there is an initial stimulation of activity by 24h after seeding, followed by a steep decline during exponential growth (48-72h). enzyme activity decreases even further as the cells reach saturation density (confluence) after 4 days in culture when the activity in normal rat kidney cell ...1979106846
synthesis of long complementary dna in the endogenous reaction by equine infectious anemia the endogenous reverse transcriptase reaction, equine infectious anemia virus is able to synthesize complementary dna (cdna) of 8,000 nucleotides in high yield. after 2 h in 50 mum dntp, about 2.8 mug of cdna per mg of protein is produced, almost 30% of which is long cdna. the system thus compares favorably with the other two well-characterized endogenous reaction systems, moloney murine leukemia virus and avian sarcoma virus. elongation rates of 100 to 150 nucleotides per min have been obser ...197987522
in vitro synthesis of infectious transforming dna by the avian sarcoma virus reverse transcriptase.infectious dna molecules, capable of transforming chicken embryo fibroblasts, can be synthesized by the rous sarcoma virus-associated reverse transcriptase in vitro. the optimal enzymatic conditions employed for infectious dna synthesis also facilitate maximum synthesis of genome length dna. analysis of the dna product synthesized by detergent-disrupted rous sarcoma virus under these conditions indicates that dna complementary to viral rna (minus-strand dna) is genome length in size, whereas dna ...197985719
host induced alteration of avian sarcoma virus b-77 genome.the genome of an avian oncornavirus was altered after infection of a heterologous host. this was studied with avian sarcoma virus b-77 in duck embryonic fibroblasts (def) and chicken embryonic fibroblasts (cef). to detect alteration of the viral genome, we hybridized 35s b-77 rna with normal duck dna by either one of two techniques:when viral rna was in excess and when dna was in excess. the rna of b-77 passaged only in gs minus chf minus cef does not have homology with duck dna. however, after ...1975165481
the induction of intractranial neoplasms by the inoculation of avian sarcoma virus in perinatal and adult rats.the induction of intracranial neoplasms following the intracerebral inoculation of avian sarcoma virus (asv) in neonatal mammals is well established. the present study demonstrates the susceptibility of adult rats and compares the incidence and morphology of tumors induced by a uniform inoculum of the bratislava-77 strain of asv in adult, neonatal, and fetal fischer 344 rats. post-inoculation mortality varied significantly between groups inoculated at 1, 10 and 100 days and was most precipitous ...1975166146
immunogenicity of the envelope glycoprotein of avian sarcoma virus.the expression of type e-specific glycoprotein in chick-helper factor-positive [chf(+)] chickens is not restricted to a certain stage of embryogenesis but persists in postembryonic life. this finding prompted an investigation of the immunogenicity of the viral envelope glycoprotein of exogenous avian sarcoma virus in chf(+) and chf(-) chickens. sensitization of both classes of chickens resulted in the induction of detectable antibody reactivity to determinants of the glycoprotein that were type- ...197877019
r-type virus-like particles in avian sarcoma virus-induced rat central nervous system tumors.morphologically distinct virus-like particles (vlp), similar to r-type vlp, were observed by electron microscopy in experimental rat central nervous system tumors induced with the b-77-c strain of avian sarcoma virus (asv). r-type vlp have a characteristic internal radial structure and were observed previously only in hamster cells and in an established bovine cell line. they were not observed in the b-77 asv inoculum used to induce the rat tumors or in the b-77 induced hamster glioma cells from ...1975166194
effect of glucosamine on virus production and antigen expression in avian sarcoma virus-transformed cells.treatment by glucosamine of avian sarcoma virus-transformed chicken embryo fibroblast (cef) cells completely inhibited the formation of progeny-transforming virus particles. such cells, however, could continue to synthesize non-infectious physical particles containing both viral rna and the enzyme rna-dependent dna polymerase if glucosamine exposure was performed in the presence of glucose. glucosamine treatment was found to affect antigenic expression in transformed cef as measured by an indire ...197881707
avian retrovirus-induced surface antigens and their cross-reactivity with chemically-transformed cells and primary embryonic cells of japanese testing spleen cells from avian leukosis (alv) and avian sarcoma virus (asv)-injected japanese quails in a microcytotoxicity assay against various target cells, we have demonstrated the existence of several target antigens. with non-transformed alv-infected japanese quail cells used as target cells, an avian retrovirus subgroup-specific destruction was obtained when spleen cells from animals infected with either avaian sarcoma or leukosis virus of the same subgroup were employed. this reactio ...197772738
virus-coded origin of a 32,000-dalton protein from avian retrovirus cores: structural relatedness of p32 and the beta polypeptide of the avian retrovirus dna polymerase.a 32,000-dalton protein (p32) located in avian retrovirus cores was immunoprecipitated from [35s]methionine-labeled avian myeloblastosis virus (amv) propagated in cultured chicken embryo fibroblast cells by an antiserum preparation (sarc iii) derived from tumor-bearing hamsters injected with cloned and passaged cells from an avian sarcoma virus-induced primary hamster tumor. since sarc iii serum apparently contained antibodies only to virus-coded proteins and not to chicken cellular proteins, th ...197881316
elongation of dna complementary to the 5' end of the avian sarcoma virus genome by the virion-associated rna-dependent dna polymerase.rna-dependent dna synthesis in a virion-associated reaction has been described as being dependent upon the detergent concentration used for disruption of the virion. in this study, the triton x-100 concentration was found to affect the elongation of the initially synthesized dna complementary to the last approximately 100 nucleotides at the 5' end of the rna (cdna100). whereas elongation of cdna100 increased with time of incubation at the optimal detergent concentration, this process was retarde ...197989203
initiation of dna synthesis by the avian retrovirus reverse transcriptase in vitro: nature and location of the oligodeoxycytidylic acid primer binding site.we have investigated the use of oligodeoxycytidylic acid [oligo(dc)] as a primer for the initiation of dna synthesis by the avian retrovirus reverse transcriptase in vitro, employing the viral rna genome as template. the addition of oligo(dc)(12-18) to viral 35s rna results in a stimulation of dna synthesis by the viral rna-directed dna polymerase comparable to that observed when oligo(dt) is employed as a primer. under similar conditions neither oligo(da)(12-18) nor oligo(dg)(12-18) was active ...197990158
antibody to virion structural proteins in mammals bearing avian sarcoma virus-induced tumors. 197874898
cellular and humoral anti-tumor immune responsiveness in chickens bearing tumors induced by avian sarcoma virus.a systematic comparison was undertaken of the respective abilities of normal chicken embryo fibroblast (cef) cells, rous sarcoma virus (rsv)- transformed cef cells, avian rous sarcoma (rs) tumor cells and murine rs cells to serve as targets and antigen donors in various assays for the detection of cellular and humoral anti-tumor immunity in chickens bearing tumors induced by rous sarcoma virus. as measured by a cytotoxicity procedure, avian and murine rs cells were more susceptible to the killin ...197768016
rnase h hydrolysis of the 5' terminus of the avian sarcoma virus genome during reverse transcription. 197875511
rna-dependent dna polymerase of avian sarcoma virus b77. ii. comparison of the catalytic properties of the alpha, beta2, and alphabeta enzyme forms.the alpha, beta2, and alphabeta forms of the rna-dependent dna polymerase of avian sarcoma virus b77 grown in duck embryo fibroblasts have been compared with respect to several kinetic properties. the following results were obtained. 1. the km values for dttp and dgtp for enzyme forms alpha, beta2, and alphabeta were 77, 39, and 74, and 6.8, 3.1, and 6.1 micronm, respectively. 2. the affinity of 70 s rous sarcoma virus rna for enzyme form alphabeta was about twice that for the other two forms. 3 ...197766235
an avian sarcoma virus mutant that is temperature sensitive for virion assembly. 1976174295
rna-dependent dna polymerase of avian sarcoma virus b77. i. isolation and partial characterization of the alpha, beta2, and alphabeta forms of the enzyme.three forms of the rna-dependent dna polymerase were isolated from highly purified avian sarcoma virus b77 grown in duck embryo fibroblasts, using sequential chromatography on deae-cellulose, phosphocellulose, and poly(u)-cellulose. one form, which sedimented with about 5.2 s, contained only one species of polypeptide, with a molecular weight of 63,000; a second sedimented with about 7.8 s and contained only one species of polypeptide with a molecular weight of 81,000; and a third form, which se ...197766234
the effect of transformation-defective avian oncornavirus mutants on tumor antigen expression.the recent isolation of conditional (temperature sensitive) and nonconditional transformation-defective mutants of avian sarcoma virus strains has facilitated the investigation of the effect of virus transformation on the cell's phenotype, e.g., with respect to morphology, growth pattern, or cell surface antigenicity. special emphasis was laid on elucidating the correlation between transformed phenotype and tumor antigen expression. all of the tested nontransforming deletion mutants and the majo ...1976176534
neoplastic transformation of mouse embryo cells by virus released from tumorigenic mouse cells transformed by avian sarcoma virus b77.mouse c3h embryo cells were transformed in vitro by avian sarcoma virus bratislava 77 (b77) released scantily from a mouse cell line transformed earlier by the same virus. b77 virus transformed c3h embryo cells contained b77 viral genome and were transplantable into syngeneic as well as allogeneic dba/2j young mice in which autochthonous sarcomas were induced. tumors in both strains of mice were virogenic. the probable reasons for an increased transformation capacity of b77 virus in mammals are ...1975175302
evidence of methylation of b77 avian sarcoma virus genome rna subunits.b77 avian sarcoma virus rna was labeled with (methyl-3h) methionine under conditions that prevent non-methyl incorporation of 3h radioactivity into purine rings. from the determined values for the extent of methylation of 4s rna isolated from infected chicken embryo cells, it was estimated that 30 to 40s rna subunits that results from heat denaturation of the 60 to 70s rna contain approximately 21 methyl groups, of which 14 to 16 are present at internal positions as n6 -methyladenosine residues. ...1976178899
purification of viral proteins from avian sarcoma virus qv2.a procedure was established whereby most of the major viral proteins were isolated to apparent homogeneity in biologically and immunologically active forms from a single batch of avian sarcoma virus qv2. for the initial step of purification, gently disrupted virions were fractionated by cscl centrifugation into envelope proteins, rna-dependent dna polymerase, and viral core proteins. further purification of envelope glycoproteins and dna polymerase was performed by affinity chromatography on aga ...1979115857
synthesis, structure and function of avian sarcoma virus-specific dna in permissive and nonpermissive cells.we have reviewed our recent evidence for the following scheme for synthesis and integration of viral dan after infection of permissive cells by asv: within the first 3 hours of infection, duplex, virus-specific dna the length of a subunit of the viral genome (3 times 10(6) daltons) is synthesized in the cytoplasm of infected cells by a virion-associated dna polymerase; viral dna probably forms a covalently closed circular duplex prior to integration into host nuclear dna. integration and the usu ...197550903
a joint produce of the genes gag and pol of avian sarcoma virus: a possible precursor of reverse transcriptase.a virus-specific protein of approximately 180,000 daltons has been identified in cells transformed by avian sarcoma virus. the protein, designated p180, includes immunological determinants of both viral core proteins and reverse transcriptase. its tryptic peptides represent essentially the sum of those of the precursor of the core proteins (pr76gag) and reverse transcriptase. thus p180 must arise from the uninterrupted translation of gag and pol. the kinetics of its formation and decay suggest t ...197774287
cell to substratum adhesion-promoting activity released by normal and virus-transformed cells in is demonstrated here that cultured fibroblasts release into their medium a nondialyzable, protease-sensitive factor(s) capable of promoting the adhesion and spreading of virus-transformed rat fibroblasts on a plastic substratum. a relatively sensitive biological assay is described for quantitation of the adhesion-promoting factor (apf) activity in serum-free, conditioned medium harvested from the cultures. evidence is presented which indicates that the primary mode of action of the apf is by ...1976182700
efficeint transcription of rna into dna by avian sarcoma virus polymerase.the dnaase digestion end-product of calf thymus dna contains oligonucleotides that will function as primers for the efficient transcription into dna of many naturally-occurring rna's by purified avian sarcoma virus rna-directed dna polymerase. the labeled dna transcripts so obtained are valuable as probes for molecular hybridization studies. typical applications of the method include the efficient transcription into dna of 18 and 28 s rrna as well as the rna's of avian sarcoma virus, polio virus ...1976183818
use of alkaline sucrose gradients in a zonal rotor to detect integrated and unintegrated avian sarcoma virus-specific dna in cells.we have attempted to distinguish integrated and unintegrated forms of avian sarcoma virus-specific dna in cells by sedimentaton through an alkaline sucrose gradient in a slowly reorienting zonal rotor. results obtained with this procedure are similar to those obtained by the more convenient analysis of networks of high-molecular-weight cell dna. most, if not all, viral dna appears completely integrated into the host cell genome in an avian sarcoma virus-transformed mammalian cell and in normal c ...1976178898
the fine structure of intracranial neoplasms induced by the inoculation of avian sarcoma virus in neonatal and adult rats.groups of f-344 rats were inoculated with the bratislava-77 strain of avian sarcoma virus (b-77 asv) within 24 hours of birth, at 9 days of age, or between 97 and 119 days of age. intracranial tumors developed in each age group. multiple tumors with mixed histologic patterns developed in rats inoculated at 1 or 9 days of age. solitary tumors with a uniform histologic pattern developed in rats inoculated as adults. on the basis of light and electron microscopic study, the majority of tumors in ea ...1976179328
temperature-sensitive changes in surface modulating assemblies of fibroblasts transformed by mutants of rous sarcoma virus.the hypothesis that surface modulating assemblies containing microfilaments and microtubules and altered after cellular transformation was tested on cells infected with temperature-sensitive mutants of avian sarcoma virus. untransformed cells (mouse 3t3 and chick fibroblasts), cells transformed by simian virus 40 (sv 3t3), and chick fibroblasts infected with schmidt-ruppin strain of rous sarcoma virus (sr-rsv-a-infected cells) were first compared for differences in microfilament and microtubule ...1976180536
evidence for animal origin of cells and rescued tumour virus from a putative human osteosarcoma cell line.human osteosarcoma cell lines t 1 and zt 1 were analyzed for host origin. the results indicated that these lines must have been contaminated with rat x mouse hybrid cells. the isolated virus was identified as an avian sarcoma virus belonging to the c subgroup.197554267
immunity against avian sarcomas: a review.animals bearing either primary or transplantable tumors of avian sarcoma virus origin frequently mount cellular and humoral antitumor immune responses against both viral and nonviral antigenic determinants. this communication summarizes recent developments in this area, with special emphasis on the effector mechanisms of antitumor immunity in chickens. among the topics considered are structural and antigenic aspects of avian leukosis and sarcoma viruses; virus-induced tumor-associated antigens; ...197659714
transformation of chinese hamster embryo cells with an avian sarcoma virus ts mutant.chinese hamster embryo cells were transformed with temperature-sensitive mutant of the schmidt-ruppin strain of rous sarcoma virus-subgroup a (ts ny68s ra-a). the developed cell line elicited the morphological transformation at a permissive temperature of 35 degrees c, whereas after a shift to a non-permissive temperature of 40 degrees c the cells reverted to a normal phenotype. tests for the presence of avian sarcoma group-specific antigen showed that the antigen was not expressed both at permi ...1976186335
defective cleavage of a precursor polypeptide in a temperature-sensitive mutant of avian sarcoma virus. 1976185801
detection and enumeration of transformation-defective strains of avian sarcoma virus with molecular hybridization. 1977190771
suppression of glycoprotein formation of semliki forest, influenza, and avian sarcoma virus by tunicamycin.tunicamycin, a new antibiotic, halts the formation of physical particles of semliki forest and fowl plague virus, whereas avian oncornavirus particles which show a reduction in infectivity and do not contain detectable labeled glycoprotein are released in the presence of the drug. in semliki forest virus-infected cells only the protein moieties of the glycoproteins could be labeled. in cells infected with fowl plague and avian sarcoma virus neither intact glycoproteins nor their protein moieties ...1976184299
detection of the major glycoproteins of friend leukemia virus (gp71) and the murine mammary tumor virus (gp52) on the surface of mouse cells.specific rabbit antisera to the major glycoproteins of friend leukemia virus (gp71) and the mouse mammary tumor virus (gp52) were utilized to study the surfaces of c3h-, dba-, balb/c-, and c57bl-transformed and normal cells by immunoelectron microscopy. antiserum to gp71 showed reactivity with all of the mouse cells tested regardless of strain, virus production, or state of transformation. in cells producing murine leukemia virus, budding viruses and other areas of the cell surface were consiste ...1976184944
nucleotide sequences in mouse dna and rna specific for moloney sarcoma virus.complementary dna (cdna) synthesized by moloney murine sarcoma virus (m-msv) was separated into two parts, the first, termed msv-specific cdna, composed of nucleotide sequences found only in m-msv viral rna, and the second, termed msv-mulv common cdna, composed of nucleotide sequences that were found in both m-msv and murine leukemia virus (mulv) viral rnas. rna complementary to the msv-specific cdna was not found in several other msv isolates, nor in ecotropic mulv, mouse mammary tumor virus, o ...1976185623
unintegrated viral dna is synthesized in the cytoplasm of avian sarcoma virus-transformed duck cells by viral dna polymerase.we have examined the location, structure, and mechanism of synthesis of unintegrated viral dna present in fully transformed cultures of avian sarcoma virus-infected duck cells. de novo synthesis of the unintegrated forms several weeks after the initial infection was documented by labeling unintegrated dna in both strands with 5-bromodeoxyuridine. the unintegrated dna is synthesized in, and probably confined to, the cytoplasm, and it consists of duplexes of short "plus" strands (ca. 0.5 x 10(6) t ...197658074
cellular immunity in rats with primary brain tumors: inhibition of macrophage migration by soluble extracts of avian sarcoma virus-induced tumors.rats bearing primary tumors of the brain induced by avian sarcoma virus (asv) were studied with the migration-inhibition factor (mif) assay for the presence of cell-mediated immunity to tumor-associated antigens. astrocytomas and sarcomas of the brain were induced in 34 neonatal f344 rats by the intracerebral inoculation of bratislava-77 asv. at weekly intervals from 4 to 9 weeks after the inoculation with virus, peritoneal exudate cells (pec) from rats bearing brain tumors were tested an an mif ...1976186622
covalently closed circular dna of avian sarcoma virus: purification from nuclei of infected quail tumor cells and measurement by electron microscopy and gel electrophoresis. 1976185393
suppression of the avian sarcoma virus genome in 8-azaquanine-resistant, transformed, hamster cells.the avian sarcoma virus genome (schmidt-ruppin strain) in transformed hamster cells resistant to 8-azaquanine [ha(sr)ag-50] was strongly suppressed. the suppression was genetically stable and could not be overcome by attempts at induction with 5-iodo-2'-deoxyuridine. fusion of hamster cells, which had suppressed virus genome, with chicken rous-associated virus (rav-1)-preinfected cells easily rescued the sarcoma virus. the rescued virus had envelope properties of rav-1, as determined by viral in ...1976187768
an in vitro study of the oncogenic effects of two variants of avian sarcoma virus b77 on rat embryonal fibroblasts.two variants of avian sarcoma virus b77 have been tested for their heteroinductive oncogenic in vitro effects on rat embryonal cells. variant 22-b77v belonging to subgroup b, had been cultured for a long time exclusively on its original host, i.e. on chicks, before being used in the study. this variant of b77v yielded negative results in repeated experiments on rat cells. variant 55-b77v belonging to subgroup c and which had been made to pass through rat cells, caused a malignant transformation ...1976187973
avian cell transformation and the expression of avian sarcoma virus-specific tumour antigens. 1976187948
infection of human embryo cells with avian sarcoma virus b77 in vitro.human embryo cells were infected with avian sarcoma virus b77--hu(b77). the virus genome was detected in the hu(b77) cells during subsequent cell passages in the uncloned cells as well as in single-cell clones. despite the presence of the virus genome in cells, the growth properties did not differ from uninfected cells. the hu(b77) cells did not reveal the transformed phenotype in vitro.1976187972
natural human antibodies reactive with primate type-c viral antigens.a survey of human sera from healthy individuals revealed the presence of naturally occurring antibodies that react in radioimmunoprecipitation assays with proteins of mammalian type-c viruses. of 39 sera tested, 100% showed reactivity against baboon endogenous virus, whereas only 49% showed reactivity against simian sarcoma-associated virus. polyacrylamide gel electrophoresis of immune precipitates revealed one to three bands that comigrate with the virus structural proteins. there were low, but ...1977191833
characteristics of virus-specific rna in avian sarcoma virus-transformed bhk-21 cells and revertants. 1977189495
characterization of dna complementary to nucleotide sequences adjacent to poly(a) at the 3'-terminus of the avian sarcoma virus genome. 1977194400
characterization of dna complementary to nucleotide sequences at the 5'-terminus of the avian sarcoma virus genome. 1977194401
influence of age at inoculation on avian oncornavirus-induced brain tumor incidence, tumor morphology, and postinoculation survival in f344 rats.intracranial neoplasms were induced by intracerebral inoculation of a standardized, cell-free inoculum of the bratislava-77 strain of avian sarcoma virus in f344 rats at 1, 9,97 to 99, and 528 days of age. deaths from diseases that occur spontaneously in aged f344 rats complicated assessment of tumor incidence in rats inoculated at 528 days; 20 of 30 rats inoculated at this age developed brain tumors. all rats inoculated at age 1 day (47 rats), at age 9 days (37 rats), and at 97 to 99 days of ag ...1977192457
variations in integration site of avian oncornaviruses in different hosts.we examined the integration site of avian oncornaviruses in the genome of different hosts with respect to the repetitive frequency of the cellular dna sequences adjacent to the integrated proviral dna. the following systems were studied: avian sarcoma virus (b-77) and avian leukosis virus (rous-associated virus-61) in cultured duck embryonic cells and b-77 in cultured mouse 3t3 cells. these systems represent different host responses to viral infection, i.e., one in which both cellular transforma ...1977189085
the role of the subependymal plate in avian sarcoma virus brain tumor induction: comparison of incipient tumors in neonatal and adult rats.f-344 rats were inoculated intracerebrally at 1 and at 133 days of age with the bratislava-77 strain of avian sarcoma virus. groups of rats were sequentially sacrificed following inoculation so that early stages of microtumor formation could be evaluated. in neonatally inoculated rats incipient tumors developed in the subependymal region of the lateral ventricles in close juxtaposition to clusters of poorly differentiated germinal cells. among these animals microtumors were detected as soon as 2 ...1977193346
spontaneous mutations affecting the host range of the b77 strain of avian sarcoma virus involve type-specific changes in the virion envelope antigen.previously it was shown that the host-range gene of the bratislava strain of avain sarcoma virus (b77 virus) spontaneously mutates with a very high rate. the wild-type b77 virus called b77 virus-ii, mutates either to virus that efficiently infects duck cells (b77 virus-iii) or to virus that does not mutate to the ability to infect duck cells (b77 virus-i) (zarling and temin, 1976). no significant differences in either the virion envelope glycoproteins or other major virion proteins were detected ...1977189060
effects of dexamethasone on the morphogenesis of two mutants of rous sarcoma virus.japanese quail cells transformed by the replication-defective, bryan high-titer strain of rous sarcoma virus, bh rsv(-)q, clone 3, revealed intracytoplasmic a-type particles after dexamethasone treatment. in the absence of dexamethasone, or when superinfected with a helper virus in the presence or absence of dexamethasone, no such particles were observed. chick embryo cells (cec) infected with a temperature-sensitive sarcoma virus mutant, la 334, coordinately defective for transformation and vir ...1978204599
translation of 35s and of subgenomic regions of avian sarcoma virus rna.rabbit antiserum monospecific for an internal structural protein, p27, of avian sarcoma viruses (asv) was found to immunoprecipitate polypeptides with molecular weights (mr) of 180,000 and 76,000 from cell-free reticulocyte lysates programmed by asv 35s rna and also from lysates of asv-infected cells. in addition, the mr 180,000 protein was also precipitated by antiserum raised against virion dna polymerase, suggesting that is a product of the two genes nearest the 5' end of virion 35s rna. we h ...1977200926
purification of dna complementary to the env gene of avian sarcoma virus and analysis of relationships among the env genes of avian leukosis-sarcoma viruses.the env gene of avian leukosis-sarcoma viruses encodes a glycoprotein that determines the host range and surface antigenicitiy of virions. we have purified radioactive dna (cdnagp) complementary to at least a portion of the env gene for viral subgroups a and c; complementary dna was synthesized with purified virions of wild-type avian sarcoma virus, and rna from a mutant with a deletion in env was used to select dna specific to env by molecular hybridization. the genetic complexity of cdnagp for ...1977189084
general immunocompetence of rats bearing avian sarcoma virus-induced intracranial tumors.the mitogenic responsiveness of spleen cells obtained from avian sarcoma virus-inoculated fischer 344 rats was studied. sixty % of the rats had astrocytomas, 13% had sarcomas, 7% had mixed gliosarcomas, and 20% had no evidence of tumors. only spleen cells from rats bearing astrocytomas had significantly diminished responses to phytohemagglutinin and concanavalin a (con a) when compared to control responses. the decreased responsiveness observed with phytohemagglutinin was limited to the optimal ...1978201377
immunobiology of primary intracranial tumors.the avian sarcoma virus-induced glioma model in rats was used to study the effectiveness of immunotherapy, namely, bacillus calmette-guérin (bcg) with or without sarcoma cells and/or chemotherapy with 1,3-bis (2-chloroethyl)-1-nitrosourea (bcnu), upon survival times. the most consistent prolongation of survival time was produced by triple therapy: bcg + intraperitoneally administered sarcoma cells + intravenously administered bcnu.1977194022
chicken macrochromosomes contain an endogenous provirus and microchromosomes contain sequences related to the transforming gene of asv.chicken chromosomes from a euploid marek's lymphoma cell line have been partially fractionated according to size by rate zonal centrifugation in a zonal rotor. dna-dna hybridization tests, using unlabeled dna extracted from gradient fractions and labeled single-stranded, virus-specific dnas prepared in vitro, indicate that large macrochromosomes harbor the provirus for the endogenous rna tumor virus of chickens (ravo), whereas a cellular sequence related to the transforming gene of avian sarcoma ...1977193646
glial-mesenchymal tropism of in vivo avian sarcoma virus neuro-oncogenesis in rats.intracerebral inoculation of avian sarcoma virus (asv) in postnatal animals induces gliomas and sarcomas but no neuronal tumors. high titer bratislava-77 strain asv was inoculated intracerebrally in fetal f-344 rats between 17 and 20 days of gestation: a time of active neuronal proliferation. following birth inoculated rats developed gliomas and sarcomas but no neuronal tumors. the results are evidence that the glial-mesenchymal tropism of in vivo asv neuro-oncogenesis is independent of stage of ...1978205079
formation of reticuloendotheliosis virus pseudotypes of rous sarcoma virus.superinfection of chicken embryo fibroblasts transformed by the defective bryan strain of rous sarcoma virus (bh-rsv) with two different reticuloendotheliosis viruses (revs), rev strain t (rev-t) or spleen necrosis virus (snv), resulted in the production of infectious sarcoma virus pseudotypes. these pseudotypes were neutralized by antiserum prepared against snv and were unable to infect chicken cells preinfected with either rev-t or snv. these results suggest that defective bh-rsv is able to us ...1977195082
identification of a transformation-specific antigen induced by an avian sarcoma virus. 1977198667
the role of the subependymal plate in glial tumorigenesis.we have studied the sequential morphological events of glial tumorigenesis in neonatal dogs, using high titer subgroup c bratislava-77 avian sarcoma virus, given as 0.01 ml by intraventricular inoculation. the cells of the subependymal plate are those which seem to form the gliomas; cytoplasmic alterations are evident within 24 h after inoculation and microfoci of gliomas, contiguous with the subependymal plate of the lateral ventricles, are visible within 7 days. independent tumors are present ...1977199034
properties of mammalian cells transformed by temperature-sensitive mutants of avian sarcoma virus.fibroblasts from european field vole (microtus agrestis) and from normal rat kidney (nrk) have been infected by avian sarcoma virus mutants which are temperature-sensitive for the maintenance of transformation. these cells are transformed at 33 degrees c, but show normal cell characteristics in morphology, colony formation in agar, saturation density, sugar uptake and membrane proteins at 39 degrees c and 40 degrees c, the nonpermissive temperatures. ts mutant virus was rescued from most of the ...1977195741
incomplete viral genome in a non-virogenic mouse tumour cell line (rvp3) transformed by prague strain of avian sarcoma virus.two cell lines, rvp3 and rva4, derived originally from mouse tumors induced by the prague and schmidt-ruppin strain of rsv, respectively, were studied. tall attempts failed to induce infectious virus production in rvp3 cells by fusion with chicken fibroblasts even if the cells were infected with avian leukosis viruses. also, attempts to rescue the viral genome by transfection were unsuccessful. rvp3 cells harboured 31-45% of the viral genome sequences, as was shown by molecular hybridization, an ...1977194849
expression of viral protein p27 in avian sarcoma virus-transformed mammalian cells and helper-dependent rescue of rous sarcoma virus. 1977194847
rous sarcoma virus-transformed avian cells express four different cell surface antigens that are distinguishable by a cell-mediated cytotoxicity-blocking test.japanese quails bearing avian sarcoma virus-induced tumors develop immune spleen cells that are cytotoxic in vitro against virally and chemically transformed cells, as well as against embryonic cells. the cell-mediated cytotoxicity can be blocked by soluble antigens extracted from in vitro cultured cells. the existence of partial as well as total blocking effects in tests with extracts from various transformed and untransformed virus-producing cells makes it possible to distinguish up to four di ...1978207774
restriction enzyme sites on the avian rna tumor virus genome.full-size single-stranded dna transcripts of the avian rna tumor virus genome were isolated from the products of the endogenous reaction of detergent-disrupted avian sarcoma virus particles. these transcripts were converted with escherichia coli dna polymerase i and 32p-labeled nucleoside triphosphates into labeled double-stranded dna. the latter dna was used to map the sites of action of seven restriction enzymes (pvu i, hpa i, kpn i, xba i, ecori, hindiii, and xho i) on the genome of three str ...1978207898
protein kinase activity associated with the avian sarcoma virus src gene product.incorporation of phosphorus from [gamma-32p]atp into protein was catalyzed by specific immunoprecipitates from avian sarcoma virus (asv)-transformed avian and mammalian cells. this incorporation was observed only when antiserum from tumor-bearing rabbits able to specifically precipitate the asv sarcoma gene product, p60src, was used to immunoprecipitate antigens from transformed cell lysates. immunoprecipitates of extracts from normal cells or cells infected with a transformation-defective asv m ...1978205879
adenylate cyclase activity and the camp level are not directly correlated with transformation by avian sarcoma viruses.the adenylate cyclase activity was measured in chick embryo fibroblasts (cef) infected with temperature-sensitive mutants (ts) of avian sarcoma virus (asv). when cef transformed with a (ts) mutant at 36 degrees c were incubated at the non-permissive temperature (41 degrees c), recovery from the low adenylate cyclase activity detectable in the transformed state was slower than the disappearance of signs of morphological transformation. after a downward shift of the temperature the activity decrea ...1977199547
surface morphology of normal and neoplastic rat cells.nontumorigenic rat cells and their tumorigenic counterparts were studied with scanning electron microscopy under controlled conditions in vitro and with transmission electron microscopy after replantation in vivo to discern if external morphology reflected the cell's neoplastic state or the etiology of transformation. interphase cells in six of seven nontumorigenic lines were flat and monolayered under confluent conditions and exhibited smooth, nonactive cell surfaces. a nontumorigenic cell line ...1977195471
evidence for splicing of avian sarcoma virus 5'-terminal genomic sequences into viral-specific rna in infected cells.the 5'-terminal nucleotide sequences of the avian sarcoma virus (asv) genome are transcribed by the reverse transcriptase in vitro into a dna transcript that represents the entire distance ( approximately 100 nucleotides) between the trna(trp) primer molecule and the 5' terminus. we have used these dna(100) transcripts in hybridization reactions with asv-specific rna from infected avian cells and find nucleotide sequences complementary to these transcripts on all of the various size classes of v ...1978206893
identification of a polypeptide encoded by the avian sarcoma virus src gene.two techniques were used to search for the polypeptide encoded by the avian sarcoma virus (asv) src gene. first, antiserum from rabbits bearing asv-induced fibrosarcomas was used to immunoprecipitate a transformation-specific antigen from asv-transformed chick embryo fibroblasts. this antigen has an apparent molecular weight (mr) of 60,000. second, the 3' one-third of the asv genome, selected by oligo(dt)-cellulose chromatography and sucrose gradient sedimentation, was translated in a mrna-depen ...1978206909
application of the transfection technique for segregation of avian tumor viruses.the possibility of clong avian tumor virus (atv) by the transfection technique was studied. the attempts required efficient facilitator for the uptake of exogenous cellular dna by chick embryo cells (cec) to increase transfection efficiency. the calcium method was more efficient than the deae-dextran method for the uptake of tritium-labeled dna, and the calcium method was used in further segregation studies of atv by transfection of cellular dna from atv-infected cells. the test viruses included ...1977211065
peptide analysis of the transformation-specific antigen from avian sarcoma virus-transformed cells.sera from rabbits bearing tumors induced by avian sarcoma virus (asv) were ussed to immunopecipitate virus-specific proteins from extracts of chicken, hamster, and field vole cells transformed by asv. two virus-specific proteins having molecular weights of 76,000 and 60,000 were found in all cell lines examined. the 76,000-molecular-weight protein, pr76, is the precursor to the internal core proteins of asv. the 60,000-molecular-weight (60k) transformation-specific antigen from each cell line wa ...1978209218
an electron microscopic method for the mapping of proteins attached to nucleic electron microscopic method for demonstrating the presence of and mapping the positions of proteins specifically bound to nucleic acids is described. the nucleic acid-protein complex is treated with dinitrofluorobenzene under conditions such that dinitrophenyl (dnp) groups are attached to nucleophilic groups on the protein, with only a low level of random attachment to the nuclei acid. this product is treated with rabbit anti-dnp igg. the position of the protein-(dnp)n(igg)m complex on the nu ...1978211486
polyethylene glycol-mediated infection with avian sarcoma this communication we report that fusion of viral and cellular membranes by polyethylene glycol is a convenient approach to overcoming genetically determined resistance to infection. using this method, avian sarcoma virus-transformed mammalian cells have been produced which serve as useful model systems for the study of rous sarcoma virus-specific tumor antigens.1978211991
nucleotide sequences related to the transforming gene of avian sarcoma virus are present in dna of uninfected vertebrates.we have detected nucleotide sequences related to the transforming gene of avian sarcoma vius (asv) in the dna of uninfected vertebrates. purified radioactive dna (cdnasarc) complementary to most of all of the gene (src) required for transformation of fibroblasts by asv was annealed with dna from a variety of normal species. under conditions that facilitate pairing of partially matched nucleotide sequences (1.5 m nacl, 59 degrees), cdnasarc formed duplexes with chicken, human, calf, mouse, and sa ...1978212733
recovery of avian sarcoma virus from tumors induced by transformation-defective mutants.transformation-defective (td) mutants of the schmidt-ruppin strain of rous sarcoma virus (rsv), which contains deletions in the gene responsible for transformation (src gene), are unable to transform chicken embryo fibroblasts in vitro. injection of some of these td mutants into newborn chickens resulted in the formation of sarcomas from which sarcoma virus was unfailingly recovered. the possibility that transforming rsv was present in the td virus preparations was excluded by further purificati ...1977200700
cycloleucine blocks 5'-terminal and internal methylations of avian sarcoma virus genome rna.cycloleucine, a competitive inhibitor of atp: l-methionine s-adenosyltransferase in vitro, has been used to reduce intracellular concentrations of s-adenosylmethionine and by this means to inhibit virion rna methylation in chicken embryo cells that are infected with b77 avian sarcoma virus. under conditions of cycloleucine treatment, where virus production as measured by incorporation of radioactive precursors or by number of infectious particles is not significantly affected, the internal m6a ...1978210799
purification of virus-specific rna from chicken cells infected with avian sarcoma virus: identification of genome-length and subgenome-leghth viral rnas.avian sarcoma virus (asv)-specific rna was purified from asv-infected cells by using hybridization techniques which employ polydeoxycytidylic acid-elongated dna complementary to asv rna as well as chromatography on polyinosinic acid-sephadex columns. the purity and nucleotide sequence composition of purified, virus-specific rna were established by rehybridization experiments and analysis of labeled rnase t1-resistant oligonucleotides by two-dimensional polyacrylamide gel electrophoresis. polyade ...1978211252
monovalent antibodies directed to transformation-sensitive membrane components inhibit the process of viral transformation.monovalent antibodies (fab) directed to two classes of transformation-sensitive cell surface components, ganglioside and galactoprotein a (gap a), inhibit the process of oncogenic viral transformation of cells. mouse 3t3 cells infected with murine sarcoma virus were not transformed in terms of morphology change and enhancement of sugar uptake when the infected cells were cultured in the presence of monovalent antibodies directed to gm(1) ganglioside or to gap a. transformation inhibitory activit ...1978216010
amino-terminal amino acid sequence of the major structural polypeptides of avian retroviruses: sequence homology between reticuloendotheliosis virus p30 and p30s of mammalian retroviruses.the major structural polypeptides, p30 of reticuloendotheliosis virus (rev) (strain t) and p27 of avian sarcoma virus b77, have been compared with regard to amino acid composition. nh2-terminal amino acid sequence, and immunological crossreactions. the amino acid composition of the two polypeptides is distinct, and a comparison of the first 30 nh2-terminal amino acids of rev p30 with that for the first 25 of b77 p27 yields only three homologous residues. in competition radioimmunoassays the poly ...1978208072
the influence of carbohydrate on the antigenicity of the envelope glycoprotein of avian myeloblastosis virus and b77 avian sarcoma virus. 1978208246
evidence that the transforming gene of avian sarcoma virus encodes a protein kinase associated with a phosphoprotein.avian sarcoma virus (asv) induces sarcomas in animals and transforms fibroblasts to a neoplastic state in cell culture. a single viral gene (src) is responsible for both the induction and maintenance of neoplastic transformation. recent work has identified a protein with a molecular weight of 60,000 daltons that is apparently encoded in src and may be the effector molecule for the gene (brugge and erikson, 1977; purchio et al, 1978). the putative product of src can be immunoprecipitated by antis ...1978214242
enhancement of avian sarcoma virus-induced tumor growth after pretreatment with bcg.pretreatment of chickens with bcg 1 week before inoculation with avian sarcoma virus had a stimulatory effect on virus-induced tumor growth in 15 of 17 cases tested. this outcome was dependent upon the injection of both bcg and the oncogenic agent into the same wing web. injection of bcg into the wing web contralateral to that used for virus inoculation or injection of a subcellular fraction of bcg into the same wing web did not affect tumor development. administration of bcg also gave rise to h ...1978215547
type c viral gag gene expression in chicken embryo fibroblasts and avian sarcoma virus-transformed mammalian cells.sensitive radioimmunoassays were developed for avian type c viral gag gene-coded proteins. these assays were used to examine the restriction to virus production by avian embryo cells and mammalian cells transformed by avian sarcoma viruses. the results indicate that although a high-molecular-weight primary translational product of the gag gene is expressed, its cleavage and processing are incomplete. furthermore, analysis of intermediate cleavage products provided information regarding the order ...1977196106
calcium requirements for the proliferation of cells infected with a temperature-sensitive mutant of rous sarcoma virus.between 32 degrees and 39 degrees, uninfected normal rat kidney (nrk) cells proliferated minimally, or not at all, in medium containing 0 to 0.01 mm extracellular free calcium. transformation of nrk cells by wild-type avian sarcoma virus b77 enabled them to proliferate equally rapidly at all temperatures in high (1.25 mm)- or low (0.001 mm-calcium medium. transformation by the temperature-sensitive la-23 mutant of rous sarcoma virus also enabled nrk cells to proliferate in low (0.001 mm)-calcium ...1978205359
transmission of b77 virus double mutant la334 markers by transfection.successful transfection of brown leghorn chicken fibroblasts was carried out with dna isolated from duck cells transformed by the la334 mutant of avian sarcoma virus b77. transfection of duck cells was negative. the four viruses recovered after transfection were all temperature-sensitive for transformation. two were fully temperature-sensitive for replication, as shown by analysis of virus replication, by characterization of virus particles produced at the nonpermissive temperature using density ...1978210141
infectivity of proviral dna from avian sarcoma virus-transformed mammalian cells.the number of rous viral genomes in the cellular dna from two subclones (rs2/3, rs2/6) derived from the same clone of hamster bhk-21 cells transformed by rous sarcoma virus was determined by hybridization with viral complementary dna made in vitro, and the capacity of the cellular dna to infect (transfect) chicken embryo fibroblasts was compared before and after shearing this dna to about the size of the provirus (6 x 10(6) to 7 x 10(6) daltons). the two subclones differed widely both in their c ...1979221676
alterations in surface proteins of rat cells transformed by avian sarcoma virus b77.cell membrane proteins of avian sarcoma virus b77v--transformed cells lwf b55 and lwf b77 and uninfected rat embryo fibroblasts were analyzed by sds acrylamide gel electrophoresis. following alterations in cell surface proteins of lwf b55 and lwf b77 cells were found: one, a slight decrease of two high molecular weight proteins the larger of which corresponds presumably to "lets" protein and a decrease of a protein with approximative molecular weight 50 000; two, increase in content of proteins ...1978216936
structural analysis of the avian sarcoma virus transforming protein: sites of phosphorylation.the avian sarcoma virus (asv) protein responsible for cellular transformation in vitro and sarcomagenesis in animals was studied structurally with special reference to the sites of phosphorylation on the polypeptide. the product of the asv src gene, pp60src, is a phosphoprotein of 60,000 daltons. we found that pp60src contained two major sites of phosphorylation, one involving phosphoserine and the other involving phosphothreonine and possible addtional minor sites of phosphorylation. by using n ...1979219258
integration of different sarcoma virus genomes into host dna: evidence against tandem arrangement and for shared integration sites.cellular dna of 50--54 s was extracted from chicken embryo cells doubly infected with two different avian sarcoma viruses and was analyzed by the infectious dna assay. approximately 80--90% of the transformed foci that were induced by this dna were found to give rise to one kind of avian sarcoma virus only, indicating that most proviral genomes are not integrated in tandem. when the two infecting viruses were varied with respect to multiplicity or time of infection, the initial infecting virus o ...1979221927
characterization of transformation-sensitive membrane-proteins in chick embryo fibroblasts transformed with avian sarcoma virus. 1978214952
characterization of the avian sarcoma virus protein p60src. 1978214955
proviruses of avian sarcoma virus are terminally redundant, co-extensive with unintegrated linear dna and integrated at many sites.we have analyzed the dna from 15 clones of avian sarcoma virus (asv)-transformed rat cells with restriction endonucleases and molecular hybridization techniques to determine the location and structure of proviral dna. all twenty units of proviral dna identified in these 15 clones appear to be inserted at different sites in host dna. in each of the ten cases that could be sufficiently well mapped, entirely different regions of cellular dna were involved. thus asv dna can be accommodated at many p ...1978215325
evidence that the avian sarcoma virus transforming gene product is a cyclic amp-independent protein kinase.the avian sarcoma virus transforming gene product pp60src has been partially purified by using ion exchange or immunoaffinity chromatography. these preparations contain a cyclic amp-independent protein kinase activity capable of transferring radiolabel from [gamma-32p]atp to immune rabbit igg, casein, and the heavy chain purified from normal rabbit igg. the casein kinase activity is specifically inhibited by anti-pp60src igg. comparison of the pp60src-protein kinase isolated from cells transform ...1979230504
morphologic characterization of proliferative cells and virus particles in turkeys with lymphoproliferative disease.the tumors found in turkeys having lymphoproliferative disease (lpd) are histologically characterized by a pleomorphic population of cells of the lymphoid series. electron microscopy has shown that, despite marked differences in shape and size, the proliferating cells share basic ultrastructural features, indicating their lymphoid origin. virus particles morphologically and morphogenetically characteristic of type c oncorna-viruses of retraviridae were found in different organs and plasma sample ...1979220455
Displaying items 1 - 100 of 714