| helper-independent transformation by unintegrated harvey sarcoma virus dna. | we have studied the unintegrated infectious dna of harvey sarcoma virus (ha-sv) and moloney leukemia virus (mo-mulv). the source of infectious viral dna was the hirt supernatant fraction from cells acutely infected with ha-sv and mo-mulv. to obtain a direct quantitative assay for infectious viral dna, recipient mouse cells were first exposed to calcium phosphate-precipitated viral dna and then treated with dimethyl sulfoxide. infectivity was monitored by focus formation for ha-sv and xc plaque f ... | 1978 | 26810 |
| assessment of reactivities of natural antibodies to endogenous rna tumor virus envelope antigens and virus-induced cell surface antigens. | the autogenous humoral immune response of mice to their endogenous leukemia virus (mulv) has been examined with respect to the reactivities of natural antibodies to mulv envelope antigens and virus-induced cells surface antigens. the natural reactivity of mulv envelope antigens was evaluated by means of a radioimmune precipitation assay of intact and disrupted virus, as well as by virus neutralization tests. the specificity of natural antibody for mulv envelope antigens was determined by immunoe ... | 1975 | 45890 |
| the morphology of murine oncornaviruses following different methods of preparation for electron microscopy. | the effect of different preparative procedures for electron microscopy on the size and shape of murine oncornaviruses has been studied. with conventional negative staining procedures using neutral sodium phosphotungstate, both murine mammary tumor virus and murine leukemia virus appeared in head-and-tail forms, with a peak head diameter of 122 and 130 nm, respectively. negative staining with uranyl accetate gave round virions with peak diameters of 148 and 130 nm. prefixed virus was round with p ... | 1975 | 46780 |
| isolation of type-c viruses from the asian feral mouse mus musculus molossinus. | n-tropic and xenotropic type-c viruses have been isolated from the wild asian mouse subspecies m. musculus molossinus. by host range, morphologic and some immunologic criteria these viruses appear closely related to the previously studied murine type-c viruses isolated from highly inbred laboratory strains of mice. | 1975 | 47844 |
| [biology of mouse rna tumor viruses]. | | 1975 | 48269 |
| biological and physical modifications of a murine oncornavirus by 2-deoxy-d-glucose. | 2-deoxy-d-glucose (2-dg) inhibited the release of transforming kirsten murine sarcoma-leukemia virus [kimsv(kimulv)] from transformed rat kidney (nrk-k) cells. at a concentration of 30 mm 2-dg, rna synthesis in nrk-k cells was inhibited by approximately 30 percent and protein synthesis was inhibited by as much as 80 percent of control levels. rna synthesis was not inhibited in nontransformed normal rat kidney (nrk) cells, although protein synthesis was equally suppressed in nrk and nrk-k cells. ... | 1975 | 49438 |
| serological studies with low-molecular-weight polypeptides from the moloney strain of murine leukemia virus. | major virion low-molecular-weight polypeptides were isolated from the moloney strain of murine leukemia virus (type c) by agarose chromatography in 6m guanidine hydrochloride and were shown to have molecular weights of 15,000 (p15), 12,000 (p12), and 10,000 (p10) by their elution volumes and by their relative mobilities in sodium dodecyl sulfate-polyacrylamide gels. each polypeptide could be iodinated and employed in double antibody radioimmunoassay procedures. all three polypeptides demonstrate ... | 1975 | 49441 |
| quantitative nucleotide sequence relationships of mammalian rna tumor viruses. | a molecular hybridization technique has been used to quantitatively measure the nucleotide sequence relationships of selected mammalian rna tumor viruses. reciprocal cross-hybridization tests were done in which a given radioactively labeled, viral genomic rna species was annealed with an excess of unlabeled, complementary dna product synthesized in endogenously instructed reverse transcriptase reactions. hybrid formation was measured with pancreatic rnase a. three representative mammalian rna tu ... | 1975 | 49442 |
| interspecies antigenic determinants of the reverse transcriptases and p30 proteins of mammalian type c viruses. | the major internal structural proteins (p30) of type c viruses isolated from several mammalian species were studied by radioimmunoprecipitation and competitive radioimmunoassays. three antigenically distinguishable sets of interspecies determinants could be demonstrated by both methods. one set of determinants shared by viruses of rodent origin (mouse and rat) can be detected readily in feline leukemia viruses but not in other type c viral groups. the p30 proteins of murine viruses also contain ... | 1975 | 49443 |
| studies on virus induction by 5-bromodeoxyuridine in nonproducer murine sarcoma virus-transformed 3t3 cells. | | 1975 | 49978 |
| interactions of chemical inducers and steroid enhancers of endogenous mouse type-c rna viruses. | | 1975 | 50667 |
| biologic and immunologic properties of porcine type c viruses. | | 1975 | 50668 |
| immunity to murine sarcoma virus induced tumours. iv. direct cellular cytolysis of 51cr labelled target cells in vitro and analysis of blocking factors which modulate cytotoxicity. | the antigen specific cell mediated cytotoxicity of msv immune spleen lymphocytes to 51cr labelled murine lymphoma cells was wholly abolished by pretreatment of the spleen cells with anti-theta antibody and complement. early during the immune response to msv the cytotoxic acitivity was inhibited by incubation of immune lymphocytes with "late progressor" or "early regressor" serum. immune lymphocytes at later times were more refractory to such inhibition by serum blocking factors. although unfract ... | 1975 | 50851 |
| characterization of murine sarcoma virus transformation of guinea pig cells and activation of an rna tumor-like virus from nonproducer guinea pig cells. | guinea pig embryo (gep) cells were transformed in vitro by the kirsten strain of mouse sarcoma virus (ki-msv). the transformed cells were found to release infectious virus continuously and produced high titers of group-specific (gs) complement-fixing (cf) antigen characteristics of the murine sarcoma-leukemia virus complex. foci of transformed cells were similar in appearance to those obtained with ki-msv in mouse and rat cells. the transformed cells produced rna dependent dna polymerase and typ ... | 1975 | 51621 |
| evolutionary nature of human reverse transcriptase and of viral-related dna synthesized in vitro by human leukemic cells. | the reverse transcriptase and endogenous dna product synthesized by virus-like particles in the cytoplasm of human leukemic cells have been studied for their genetic relatedness to homologous components obtained from several animal rna tumor viruses. the human reverse transcriptase activity was inhibited by antibodies prepared against reverse transcriptase from some animal rna tumor viruses. the dna molecules synthesized endogenously by the human cytoplasmic particle in the presence of actinomyc ... | 1975 | 51636 |
| murine intracisternal type a particles: a biochemical characterization. | intracisternal a particle preparations from a murine neuroblastoma cell line (n18) and from a mineral oil-induced murine plasmacytoma (mopc-104e) contain both an endogenous rna-dependent dna polymerase activity and high molecular-weight polyadenylic acid (poly[a])-containing rna. the dna polymerase activity is stimulated by oligo(dg)-poly(c) and oligo(dt)-poly(a) and to a lesser extent by oligo(dt)-poly(da), in agreement with previous reports. the high-molecular-weight rna is predominantly 35s a ... | 1975 | 51937 |
| host range studies of flopc-1 murine myeloma c particles. | the host range of the c particle produced by flopc-1 myeloma cells, flopc-1 murine myeloma-associated virus (fl-mumav), was assessed in terms of its ability to productively infect and/or induce new viral antigens in a variety of different cell lines. production of c particle-like structures by cells exposed to fl-mumav) was determined by incorporation of [3h]uridine into particles with a density of 1.16 g/ml and/or measurement of rna-dependent dna polymerase activity in concentrated culture medi ... | 1975 | 52724 |
| murine sarcoma virus defectiveness. viral polymerase expression murine and nonmurine host cells transformed by s+l-type murine sarcoma virus. | | 1975 | 52940 |
| species and interspecies radioimmunoassays for rat type c virus p30: interviral comparisons and assay of human tumor extracts. | the major internal protein, p30, of rat type c virus (ralv) was purified and utilized to establish intra- and interspecies radioimmunoassays. three rat viruses were compared in homologous and heterologous intraspecies assays with no evidence of type specificity. the only heterologous viruses to give inhibition in these species assays were the feline (felv) and hamster (halv) type c viruses; these reactions were incomplete and required high virus concentrations. an interspecies assay using a goat ... | 1975 | 54444 |
| mouse msv transformed cells resistant to 8-azaguanine. | mouse cells transformed by murine sarcoma virus were made resistant to 8-azaguanine. resistant cells and cell clones isolated from them were deficient in hypoxanthine-guanine phosphoribosyl transferase (hgprt) activity. they did not grow in hatg medium, did not incorporate labeled hypoxanthine, and had negligible hgprt activity. the resistance was genetically stable. the resistant cells were hyperdiploid and contained telocentric chromosomes only. the resistant cells as well as the progenitor ce ... | 1975 | 55981 |
| relationships between intracisternal type a and extracellular oncornavirus-like particles produced in murine mopc-460 myeloma cells. | oncornavirus-like particles of the "a" (both intracisternal and intracytoplasmic) and "b" or "c" (extracellular) types are produced by murine mopc-460 myeloma cells. this communication describes a comparative study on tracisternal a and extracellular particles. both types of particles contain an rna-dependent dna polymerase activity, traces of 35s and 70 s rna in addition to larger amounts of degraded rna, and proteins of approximately 76,000 and 45, 000 daltons. the 76,000-dalton proteins from ... | 1976 | 56464 |
| induction of a novel transforming virus (msv-z) from sarcoma-positive leukemia-negative 3t3fl mouse cells. | | 1976 | 56806 |
| properties of murine intracisternal a particles: electron microscopic appearance after critical point drying and platinum shadowing. | | 1976 | 56810 |
| murine sarcoma virus defectiveness: serological detection of only helper virus reverse transcriptase in sarcoma virus rescued from nonmurine s + l-cells. | | 1976 | 57666 |
| identification of infectious virions which are vesicular stomatitis virus pseudotypes of murine type c virus. | | 1976 | 57669 |
| intracisternal a particles from flopc-1 balb/c myeloma: presence of high-molecular-weight rna and rna-dependent dna polymerase. | intracisternal a particles from the flopc-1 line of balb/c myeloma have been shown to contain high-molecular-weight rna (60 to 70s) that is sensitive to rnase, alkali degradation, and heat but resistant to pronase treatment. the intracisternal a-particle rna contains tract of poly (a) approximately 180 nucleotides long. as shown in a reconstitution experiment, by antigenic analysis of a-particle preparation and the sc cytopathogenicity assay, the 70s rna was not due to contamination by type c vi ... | 1976 | 58076 |
| radiommunoassays for the 70,000-molecular-weight glycoproteins of endogenous mouse type c viruses: viral antigen expression in normal mouse tissues and sera. | genetic information coding for type c rna viruses is transmitted within the dna of mouse cells. at least three endogenous viruses have so far been immunologically distinguished by radioimmunoassays for their 12,000-molecular-weight polypeptides (p12). in the present study, the 70,000-molecular-weight glycoproteins (gp70) of three prototype viruses were purified, and competition radioimmunoassays were developed for each. by use of these immunoassays, the antigenic determinants of gp70's of differ ... | 1976 | 58081 |
| neutralization of homologous and heterologous oncornaviruses by antisera against the p15(e) and gp71 polypeptides of friend murine leukemia virus. | | 1976 | 58469 |
| genetic transformation of animal cells with viral dna of rna tumor viruses. | | 1976 | 58548 |
| expression of murine oncornavirus proteins in synchronized cells. | | 1976 | 59457 |
| sequence homology between moloney murine sarcoma virus and moloney leukemia virus rna. | the moloney murine sarcoma-leukemia virus [m-msv (mulv)], propagated at high multiplicity of infection (moi), was demonstrated previously to contain a native genome mass of 4 x 10(6) daltons as contrasted to a mass of 7 x 10(6) daltons for moloney murine leukemia virus (m-mulv). the 4 x 10(6)-dalton classof rna from m-msv (mulv) was examined for base sequence homology with dna complementary to the 7 x 10(6)-dalton m-mulv rna genome. approximately 86% of the m-msv (mulv) was protected from rnase ... | 1976 | 59817 |
| antigenic specificity of cell-mediated antitumor reaction in the msv system. | | 1975 | 60997 |
| assay for type c virus in mouse sera based on particulate reverse transcriptase activity. | assay of particulate reverse transcriptase activity in the sera from feral mice naturally infected with type c virus provides a sensitive and rapid procedure for the determination of in vivo virus infection. the results compare well with assays for infectious virus and with complement fixation or competitive radio-immunoassays for the p30 internal antigen of the virus. | 1976 | 61284 |
| revertants of human cells transformed by murine sarcoma virus. | revertants of nonproducer human osteosarcoma (np/khos) cells induced by kirsten murine sarcoma virus were isolated after incubating at high temperature (40.5 degrees c) overnight and subcloning at 36 degrees c. the morphologic variants, from which murine sarcoma virus could no longer be rescued, had growth properties similar to those of the nontransformed, parent human osteosarcoma cells and did not release rna-dependent dna polymerase activity. these revertants were nontumorigenic in nude mice. ... | 1976 | 62397 |
| inactivation of murine rna tumor viruses by isatin beta-thiosemicarbazone, its derivatives and analogs. | | 1976 | 62447 |
| selective techniques for the isolation of morphological revertants of sarcoma virus-transformed cells. | | 1976 | 63892 |
| cell cycle-dependent inhibition of kirsten murine sarcoma-leukemia virus release by cytochalasin b. | | 1977 | 65050 |
| the murine sarcoma virus-induced tumor: exception or general model in tumor immunology? | | 1977 | 66859 |
| rna sequences specifically associated with mouse intracisternal a particles. | | 1977 | 68836 |
| distinction between envelope antigens of murine xenotropic and ecotropic type c viruses by immunoelectron microscopy. | the indirect ferritin-labelled antibody technique was used to determine the reactivity of an antiserum prepared against the nzb xenotropic virus with three murine xenotropic viruses, a feline xenotropic virus and a murine ecotropic virus. the envelope antigens of the xenotropic type c viruses isolated from the nzb, nih swiss and c57l mice were tagged with ferritin. the feline rd114 virus was not. gross murine leukaemia virus was tagged, but only at high serum concentrations. the cross-reactivity ... | 1977 | 69013 |
| a new class of murine retroviruses: immunological and biochemical comparison of novel isolates from mus cervicolor and mus caroli. | | 1977 | 70107 |
| [evidence of protein kinase activity in 2 murine oncornaviruses]. | a protein kinase activity has been detected in two strains of murine oncornaviruses, msv/mlv and efv. this activity phosphorylates not only endogenous viral proteins but also exogenous substrates (histones and phosvitin). the stimulation of enzyme activity by detergents along with the increase of specific activity in viruses treated with trypsin during purification suggest that the enzyme is located in the viral particle. | 1977 | 71220 |
| endogenous mink (mustela vison) type c virus isolated from sarcoma virus-transformed mink cells. | a previously described type virus stock (designated pp-1r), isolated by cocultivating baboon cells with mink cells transformed by kirsten sarcoma virus (64j1), has been further cloned and characterized. end point-diluted stocks of pp-1r have been obtained that are free of focus-forming activity and lack both kirsten sarcoma and primate type c viral sequences. nucleic acid hybridization experiments show that the cloned virus (milv) is an endogenous, genetically transmitted virus of the mink (mus ... | 1978 | 76684 |
| multiple rnase h activities in mammalian type c retravirus lysates. | lysates of moloney murine sarcoma-leukemia virus [m-msv(mlv)], a virus complex grown in the rat cell line 78a-1, were found to contain three rnase h species separable by polycytidylic acid[poly(c)]-agarose chromatography. rnase h activity (rnase h i) associated with rna-directed dna polymerase eluted at 0.23 m kci from poly(c)-agarose. rnase h ii, which eluted from poly(c)-agarose at 0.12 m kci and was not associated with dna polymerase activity, was shown to be identical to an rnase h species ( ... | 1978 | 77333 |
| interstrain variation of the major internal structural component (p30gag) of two murine oncornaviruses: comparative immunochemical, biochemical, and biophysical analysis. | the major internal structural protein (p30(gag)) of the moloney leukemia virus and the endogenous y-1 murine oncornavirus was examined for biochemical and biophysical manifestations of interstrain antigenic variation. although the two viral proteins share murine group-specific antigenic determinants, the y-1 virus p30 appeared to have both a lower relative number of such determinants and a decreased affinity at the cross-reactive sites for moloney virus p30 monospecific antibodies. further, immu ... | 1978 | 77912 |
| inhibition of oncornavirus functions by poly (2-methylthioinosinic acid). | poly (2-methylthioinosinic acid) [poly(ms2i)] was found to markedly inhibit the rna directed dna polymerase (reverse transcriptase) activity of murine (moloney, rauscher) leukemia virus and murine (moloney) sarcoma virus, while under the same conditions the unsubstituted parent compound poly(i) showed little, if any, inhibitory effect. copolymers of inosinic acid (i) and 2-methylthioinosinic acid2(ms2i) showed an intermediary effect, depending on the i:ms2i ratio. poly(ms2i) also inhibited the t ... | 1975 | 79996 |
| origin and biological properties of a new balb/c mouse sarcoma virus. | a focus-forming virus previously isolated from a balb/c mouse hemangiosarcoma has been shown to be replication defective. analysis of individual balb/c mouse sarcoma virus (balb-msv) nonproducer transformants for expression of helper virus-coded proteins revealed genetically stable variants that expressed two, three, or all four gag gene products in the absence of detectable helper viral env gene expression. the type-specific antigenic determinants of helper viral proteins encoded by the balb-ms ... | 1978 | 80461 |
| reticuloendotheliosis virus: detection of immunological relationship to mammalian type c retroviruses. | reticuloendotheliosis virus (rev) p30 shares cross-reactive determinants and a common nh2-terminal tripeptide with mammalian type c viral p30's. an interspecies competition radioimmunoassay was developed, using iodinated rev p30 and a broadly reactive antiserum to mammalian virus p30's. the avian leukosis-sarcoma viruses and mammalian non-type c retroviruses did not compete in this assay. previous data indicating that the rev group is not represented completely in normal avian cell dna lead us t ... | 1979 | 87519 |
| use of trypsin for rapid and efficient purification of murine sarcoma and leukemia virus. | a method is described for purification of msv-mulv from culture supernatant of chronically infected 78a,1 rat embryo cell line. this method involves direct polyethylene glycol-nacl precipitation of the low speed supernatant of culture fluid followed by digestion of the pellet with trypsin. this procedure efficiently disrupts large aggregates which normally entrap most of the virus. highly purified virus can be obtained in very good yield by a combination of sedimentation velocity and isopycnic c ... | 1978 | 88963 |
| avian reticuloendotheliosis viruses: evolutionary linkage with mammalian type c retroviruses. | reticuloendotheliosis viruses have been shown to be causative of tumors in a variety of avian species. the major structural protein of these non-genetically transmitted viruses is demonstrated to possess antigenic determinants common to those of all known mammalian type c viruses. these findings establish a mammalian origin for this oncogenic avian retrovirus group. none of the known mammalian type c virus groups demonstrated a closer immunological relationship to avian reticuloendotheliosis vir ... | 1979 | 89204 |
| purification of protein kinase of mouse sarcoma virus and its effect on reverse transcriptase activity. | | 1979 | 89847 |
| mhc-restricted cytotoxic t cells: studies on the biological role of polymorphic major transplantation antigens determining t-cell restriction-specificity, function, and responsiveness. | | 1979 | 92183 |
| unlimited division potential of precancerous mouse mammary cells after spontaneous or carcinogen-induced transformation. | serial transplantation of normal mouse mammary gland in young, isogenic hosts results in progressive loss of division potential, and the transplant line is eventually lost. this is interpreted as an expression of senescence at the cell and tissue level, and it inevitably occurs even though experimental conditions for growth are judged to be optimal. an indefinite extension of mammary growth span can be accomplished by transformation of these normal cells into precancerous cell types, which grow ... | 1975 | 162797 |
| host range of murine xenotropic virus: replication in avian cells. | | 1975 | 163009 |
| virus-specific dna sequences in mouse and rat cells transformed by the harvey and moloney murine sarcoma viruses detected by in situ hybridization. | | 1975 | 163051 |
| letter: comments on the guest editorial on a proposed reclassification of murine type-c rna viruses. | | 1975 | 163323 |
| editorial: spleen focus-forming virus in friend and rauscher leukemia virus preparations. | | 1975 | 163329 |
| phosphoproteins: structural components of oncornaviruses. | oncornaviruses, which contain a virion-associated protein kinase, were found to possess phosphoproteins as virion structural components. one major phosphoprotein common to strains of laboratory and wild mouse oncornaviruses and a strain of feline leukemia virus was shown to be a polypeptide of about 12, 000 mol wt. in addition to this, the kirsten strain of murine sarcoma virus contained a second major phosphoprotein of about 10, 000 mol wt, and mouse erythroblastosis virus contained a second ma ... | 1975 | 163371 |
| secondary scanning electron microscopy of cells infected with murine oncornaviruses. | | 1975 | 163529 |
| a comparison of the effects of daunomycin and adriamycin on various dna polymerases. | the effects of the anthracycline antiboties, daunomycin and adriamycin, on the dna-directed activities of dna polymerases from murine sarcoma virus, rat liver (high-molecular-weight species), escherichia coli, and micrococcus luteus were determined. under all conditions tested, these compounds had greater inhibitory effect against the viral polymerase than against cellular polymerase. the inhibition of murine sarcoma virus dna polymerase by daunomycin was competitive with respect to dna. for vir ... | 1975 | 163690 |
| studies of fbj osteosarcoma virus in tissue culture. ii. autoinhibition of focus formation. | a high-titered non-focus-forming virus, fbj-mulv (murine leukemia virus), present in fbj tumor preparations, inhibited significantly the expression and production of fbj-musv (murine sarcoma virus) in tissue culture. this "autoinhibition" was comparable to that observed when a 3- to 4-log excess of infectious mulv was added to standard musv. the degree of inhibition was influenced by the tropism of the mulv (or the ease of spread and propagation of mulv in certain cells), multiplicity of infecti ... | 1975 | 164561 |
| aberrant viruses in cells infected with murine sarcoma virus-feline leukemia virus. | this study describes an unusual type of virus seen when a feline leukemia virus (felv) pseudotype of murine sarcoma virus (musv) obtained by cocentrifugation procedures infected feline embryo cells (fef) and two crandell cat cell lines (crfk1, crfk2). when all three cell cultures were infected with musv-felv, only fef and crfk2 were transformed and only these showed normal and aberrant virus. the crfk1 infected with musv-felv did not transform but did replicate normal type-c virus with a 50-a in ... | 1975 | 164569 |
| moloney sarcoma virus-induced tumors in athymic (nude) mice: growth pattern and antibody responses. | tumor growth and antibody production were evaluated in nude (nu/nu) mice and their heterozygous normal (+/nu) littermates after inoculation of moloney sarcoma virus (msv). sarcoma-bearing nude mice developed progressively growing tumors, whereas 53 percent of their normal counterparts showed tumor regressions. by indirect membrane fluorescence, significant amounts of igg antibody to msv could be detected in thymus-bearing but not in nude mice. | 1975 | 164570 |
| viral-related information in oncornavirus-lik particles isolated from cultures of marrow cells from leukemic patients in relapse and remission. | characterization of ribonucleic acid content of particles released from cultures of marrow cells of leukemic patients indicates the presence of rna molecules of size and base sequence characteristic of oncornarviruses. seventeen marrow samples obtained from leukemic patients in relapse or in a chronic phase of the disease yielded particles containing high-molecular-weight rna with a sedimentation velocity (about 70 s) similar to that obtained for murine oncornavirus rna. eight of nine marrow sam ... | 1975 | 164662 |
| effect of diethylaminoethyl-dextran on the replication of a murine sarcoma (moloney)-leukemia virus complex in mouse embryo cultures (38577). | isolates of a sarcoma (moloney)-leukemia virus complex prepared as cell-free extracts from mouse tumors showed no enhancement in infectivity by deae-d either in the sarcoma moiety measured by focus formation or in the leukemia moiety measured by xc cell assay. the sarcoma moiety was not enhanced by deae-d in mem and modified mccoy's 5a media or when varying amounts of fcs and glutamine were included in the media. progressive enhancement of viral infectivity by deae-d was found when the viral p ... | 1975 | 164673 |
| non-producer human cells induced by murine sarcoma virus. | non-produces (np) human cells were isolated from transformed foci induced by the kirsten mouse sarcoma virus. these morphologically altered np cells produced neither infectious virus nor complement-fixing antigens of the murine sarcoma-leukemia virus complex. however, the sarcoma virus genome could be rescued from these nf cells by co-cultivation with cells carrying "helper" kirsten mouse leukemia virus or woolly monkey leukemia virus. the possible usefulness of these cells in efforts designed t ... | 1975 | 165148 |
| transformation of horse skin cells by type-c sarcoma viruses. | a horse skin cell line (e. derm, nbl-6, ccl-57) was susceptible to focus formation by the kirsten mouse sarcoma virus, feline sarcoma virus (st stain) and the msv pseudotypes with woolly monkey, gibbon monkey, rd-114, at-124, baboon placenta and murine xenotropic (balb/c 3t3 and c57l/jd) type-c viruses. foci were detected within 5 days after infection and the transformed cells continued to produce infectious virus and group-specific antigen of their respective type-c leukemia viruses. the transf ... | 1975 | 165152 |
| effect of protease inhibitors on focus formation by murine sarcoma virus. | the effect of six protease inhibitors, isolated from various species of actinomycetes, on focus formation by murine sarcoma virus was examined. pepstatin was the only inhibitor. the treatment of cells with pepstatin at various times possibly retards the early stage of infection with murine sarcoma virus. | 1975 | 165316 |
| effect of cordycepin on the replication of type-c rna tumor viruses. | cordycepin (3'-deoxyadenosine) was previously shown to inhibit virus production induced by iododeoxyuridine from murine fibroblasts (wu et al., 1972). we now report that the inhibitory effect of cordycepin results in a reduction of the number of cells producing virus as measured by the infectious center assay and fluorescent antibody technique. cordycepin has a much greater inhibitory effect on viral replication than on transformation of normal rat kidney cells by murine sarcoma virus since vira ... | 1975 | 166934 |
| effects of steroid hormones on replication of murine sarcoma virus in mouse embryo cultures. | the androgenic steroid hormone, testosterone, inhibited focus formation by the murine moloney sarcoma virus in mouse embryo cells. the inhibition of focus formation was enhanced by cyclic amp. although focus formation was inhibited, there was no inhibition of viral replication. the glucogenic adrenal corticosteroids, cortisol and dexamethasone, and 17-beta-estradiol and progesterone did not affect focus formation by musv(m). | 1975 | 167384 |
| efficient release of murine xenotropic oncornavirus after murine leukemia virus infection of mouse cells. | | 1975 | 167521 |
| sarcoma-negative leukemia-positive transformed cell culture established from a murine sarcoma virus-induced rat bone tumor. | inoculation of the soehner-dmochowski isolate of the moloney strain of murine sarcoma virus (msv), designated msv-sd, consistently leads to the development of bone tumors in the susceptible new zealand black (nb) rats. two separate cell cultures have been established from 2 individual msv-sd-induced nb rat bone tumors. cells of 1 bone tumor culture, designated rbt-e, are in early in vitro passages. these cells form colonies in agar medium and take up 2-deoxy-d-[3h]glucose at a greatly enhanced r ... | 1975 | 167960 |
| heat sensitivity of murine sarcoma virus. | murine sarcoma virus (moloney) was found to be heat labile. inactivation curve represents a first-order kinetics at temperatures between 30 degrees and 60 degrees. inactivation constant analysis showed an inflexion at about 45 degrees, and the activation energy was calculated as 67.6 kcal/mol for higher temperature range and 7.95 kcal/mol for lower temperature range. nature of inactivation is also discussed. | 1975 | 168117 |
| secondary cell-mediated cytotoxic response to syngeneic mouse tumor challenge. | when c57bl/6 mice previously immunized with murine sarcoma virus (msv) were challenged with a rauscher virus-induced lymphoma, rbl-5, a secondary cell-mediated cytotoxic response could be detected by the cr release cytotoxicity assay. the level and distribution of the secondary cytotoxic response was affected by the route of challenge. animals injected i.p. demonstrated a high level of cytotoxicity in the peritoneal exudate cells 3 days after challenge and subsequently cytotoxicity was detected ... | 1975 | 168259 |
| expression of mouse mammary tumor viral polypeptides in milks and tissues. | a 14,000-dalton polypeptide (p14) from riii murine mammary tumor virus (mmtv) has been isolated by column chromatography in 6 m guhcl. antiserum prepared in rabbits specifically precipitated 125i-labeled p14; in double antibody competition, radioimmunoassays performed with limiting amounts of antibody, both purified p14 and disrupted mmtv, competed specifically with labeled antigen. the expression of this mmtv type b virus antigen could be measured by competition radioimmunoassays in milks, mamm ... | 1975 | 168263 |
| murine sarcoma virus pseudotypes acquire a determinant specifying n or b tropism from leukaemia virus during rescue. | | 1975 | 168499 |
| induction of erythroid leukaemia by harvey and kirsten sarcoma viruses. | | 1975 | 168500 |
| base sequence differences between the rna components of harvey sarcoma virus. | the 50 to 70s rna of the harvey sarcoma-moloney leukemia virus (mlv) complex consists of 30 to 40s rna subunits of two different size classes and contains sequences homologous to moloney mouse leukemia virus and to information contained in a c-type rat virus, termed nrk virus. we have isolated by preparative gel electrophoresis the large (component 1) and the small (component 2) 30 to 40s rna species from the harvey sarcoma-mlv complex. harvey rna component 1 was completely complementary to dna ... | 1975 | 169396 |
| cyclic amp-mediated transformation of rat cells transformed by temperature-sensitive mouse sarcoma virus. | | 1975 | 169472 |
| transformation of cultured rat liver cells by murine sarcoma viruses. | cultured liver cells (trl-2 cells), originating from a bd-6 rat, an inbred black rat strain, and possessing several marker enzymes, and characteristic ultrastructures of hepatic cells, were infected with murine sarcoma viruses (msv: kirsten and gazdar strains). on day 5-6 after virus inoculation, the monolayered epithelial cells focally began to pile up forming small polypoid projections, and on day 7 round-shaped cells were released from the polypoid foci. these cells first grew in a chain or a ... | 1975 | 169808 |
| control of reversion of moloney virus sarcoma virus transformed cells. | mouse cells transformed by the moloney murine sarcoma virus (msv) native to the species can give rise to revertants which are supersusceptible to a second cycle of transformation. the msv retransformed cells can give rise to several complex functional states even after several cycles of cloning: a) formation of sarcoma positive, leukemia negative (s+lminus) type cells of which some sublines may be inducible for msv by halogenated pyrimidines; b) detection of initially sminuslminus cells which sp ... | 1975 | 169824 |
| in vivo interactions between murine leukemia and sarcoma viruses. | experiments have been performed with the aim of elucidating the nature and the extent of the in vivo interactions between murine leukemia viruses (mulvs) and murine sarcoma virus (msv). balb/c and cba mice, injected neonatally with graffi or passage a gross viruses (mulv-gi, mulv-g), have been inoculated as young adults with murine sarcoma virus, moloney strain (msv-m). a higher percentage of nonregressing sarcomas appeared in these animals, sometimes accompanied simultaneously by leukemia. the ... | 1975 | 169829 |
| genetics of endogenous mouse c-type viruses. | | 1975 | 169833 |
| genetic control of oncogenesis by murine sarcoma virus moloney pseudotype. i. genetics of resistance in akr mice. | infection of moloney mouse sarcoma virus (m-msv) in adult mice of several inbred strains revealed that all strains except akr are highly susceptible to m-msv tumor development. f1 hybrids between akr and cba, dba/2 or nih mice are as resistant (93%) as the parental akr strain, which indicates that resistance is transmitted as a dominant character. first backcross mice to the susceptible parent show a 3:1 ratio of resistant to susceptible mice. this is the expected ratio for two segregating loci ... | 1975 | 170219 |
| genetic control of oncogenesis by murine sarcoma virus moloney pseudotype. ii. a dominant epistatic susceptibility gene. | we have shown in the preceding paper that akr mice are highly resistant to m-msv tumor development, and that resistance is transmitted as a dominant character. in the present studies the tumor-response pattern of f1 hybrids between resistant akr and susceptible strains (c57bl/6, balb/c and b10br) following injection with moloney mouse sarcoma virus (m-msv) resembles that of the non-akr parent. segregation is observed in first backcross (bc1) and f2 mice, and the segregation ratios up to bc3 mice ... | 1975 | 170220 |
| clonal variation of the mouse cells in the endogenous c-type virus induction by 5-iodo-2'-deoxyuridine. | using an mlg cell line originating from a single newborn ddy mouse, n-tropic c-type virus able to infect the cells or origin was induced by 5-iodo-2'-deoxyuridine (iudr). all the clones isolated from the mlg cell line released the virus after iudr-treatment. there was more than a 100-fold difference in the virus inducibility between the highly and lowly inducible clones. the [125i]iudr incorporation was, however, the same for the both types of clones. when the induced virus was titrat-d in the s ... | 1975 | 170368 |
| derivation of mouse sarcoma virus (kirsten) by acquisition of genes from heterologous host. | the technique of virus rna-cellular dna hybridization in solution with dna excess was used to compared the nucleotide sequences of the 70 s rna genome of the kirsten mouse sarcoma virus (ki-msv) with that of mouse erythroblastosis virus (mev) which gave rise to ki-msv after in vivo propagation in rat. it is suggested that a loss of about 30% of the genomic sequences of mev with a concomitant gain of roughly equal amounts of rat-specific sequences in a genetically stable recombinant state led to ... | 1975 | 170369 |
| kinetics of murine type c virus-specific dna synthesis newly infected cells. | replicating transforming functions of rauscher leukemia virus (rlv) and the rlv pseudotype of moloney sarcoma virus in mouse embryo fibroblasts were found to be most sensitive to inhibition by cytosine arabinoside (ara-c) 30 to 90 min after infection. the initiation of intracellular rlv dna synthesis was detected by nucleic acid hybridization within this time interval. treatment of infected cells with cytosine arabinoside abolished rlv dna synthesis. peak synthesis of the dna complementary to th ... | 1975 | 170417 |
| size of virus-specific rna in b-34, a hamster tumor cell producing nucleic acids of type c viruses from three species. | b-34 is the designation of a hamster tumor-derived cell line induced by the harvey sarcoma virus. this cell line produces virions which contain structural proteins common to edogenous hamster viruses and nucleic acid sequences of hamster, mouse, and rat origin. the sedimentation characteristics of the intracellular virus-specific rna was determined in sucrose gradients after treatment with dimethylsulfoxide by molecular hybridization using complementary dna of strict virus specificity. hamster v ... | 1975 | 170418 |
| [origin of rodent sarcoma viruses and characteristics of the genome rna (author's transl)]. | | 1975 | 170648 |
| characterization of non-producer human cells induced by kirsten sarcoma virus. | non-producer (np) human cells induced by the kirsten sarcoma virus were characterized. these morphologically altered np cells produced neither infectious virus nor complement-fixing antigens of the murine sarcoma-leukemia virus complex. the np cells did not release rna-dependent dna polymerase and type-c virus particles with a density of approximately 1.15 g/ml in sucrose gradients by 3h-uridine labelling. the np cells produced tumors when transplanted subcutaneously into athymic nude mice. the ... | 1975 | 171229 |
| adaptation of n-tropic friend leukaemia virus and its murine sarcoma virus pseudotype of non-permissive b-type c57bl/6 mouse cell line. | n-tropic friend leukaemia virus (flv) was serially passaged in a b-type c57bl/6 mouse cell line, yh-7. after a single passage, the infectious efficiency of flv in the restrictive yh-7 cells was significantly increased. this adapted character of flv could be reversed by a single passage in permissive n-type mlg cells. the true host range conversion from n to nb was accomplished after eleven to twelve passages in yh-7 cells. in contrast, the host range conversion of n-tropic murine sarcoma pseudot ... | 1975 | 171332 |
| two levels of restriction by mouse or cat cells of murine sarcoma virus coated by endogenous xenotropic oncornavirus. | mouse and cat cells were each examined for the mode of restriction of endogenous xenotropic oncornavirus. murine xenotropic helper virus (mux) and its pseudo-type of moloney murine sarcoma virus (msv(mux)) were grown in cat cells to high titre. mux alone did not replicate in any mouse cell tested including normal or transformed outbred swis 3t3 cells or sc-i cells, but did grow in a variety of other mammalian cells. msv(mux) was not able to achieve that intracellular state from which it could be ... | 1975 | 171336 |
| murine oncornavirus activation in the pancreas during infection with venezuelan equine encephalitis virus. | electron microscopic studies of the pancreases of 3-week-old icr swiss mice infected with venezuelan equine encephalitis virus and killed 6 days post inoculation (at which time they were moribund) indicated significantly more type-c particles than were found in uninfected controls. this phenomenon was apparently possible because of the microanatomy of the pancreas, in which interstital spaces allowed accumulation of virus particles. | 1975 | 171430 |
| symposium: characterization of oncornaviruses and related viruses--a report. | | 1975 | 171431 |
| requirement for cellular protein synthesis in reversal of ethidium-bormide-induced inhibition of cell transformation by murine sarcoma virus. | cultures of mouse balb 3t3 fibroblasts exposed to a noncytotoxic dose of ethidium bromide for 16-18 hr are unable to produce foci after infection with murine sarcoma virus. such cultures regain susceptibility to infection when incubated for 6-8 hr in drug-free growth medium. pretreated but not untreated cultures exhibit sensitivity toward brief (6 hr) exposure to cycloheximide, chloramphenicol, and actinomycin d before infection. pretreatment with cordy-cepin inhibits the ability of cultures to ... | 1975 | 172904 |
| separation of sarcoma virus-specific and leukemia virus-specific genetic sequences of moloney sarcoma virus. | we have studied the nucleic acid sequences in nonproducer cells transformed by moloney sarcoma virus or abelson leukemia virus (two types of replication-defective, rna-containing, viruses isolated by passage of moloney leukemia virus in balb/c mice). dna probes from the moloney leukemia in virus detect rna in both abelson virus-transformed nonproducer cells and moloney sarcoma virus-transformed nonproducer cells. a sarcoma-specific cdna, prepared from the moloney sarcoma virus, has extensive hom ... | 1975 | 172913 |
| nucleotide sequences in the rna of mammalian leukemia and sarcoma viruses. | | 1975 | 173318 |
| proceedings: evidence for a protein synthesis requirement early in the infectious cycle of the murine sarcoma-leukemia virus. | | 1975 | 173689 |
| quantitative analysis of the rescue of rna sequences by mammalian type c viruses. | the specificity and quantitation of the rescue of rna sequences by mammalian type c viruses has been investigated. type c virus can package with specificity only type c viral rna. type c viruses do not encapsidate with comparable efficiency either type b viral or cellular globin mrna. conversely, a non-type c mammalian retravirus, mp-mv, cannot encapsidate type c rna. a revertant of kirsten sarcoma virus (ki-sv)-transformed nonproducer cells which fails to rescue biologically active ki-sv after ... | 1975 | 173892 |