| tyrosine aminotransferase induction in normal and tumor-bearing chickens. | tyrosine aminotransferase (tat) induction by glucagon and dexamethasone in the liver of tumor-bearing chickens was studied and compared with induction in healthy animals. the transplantable tumor was caused by inoculation of cells from a cell line induced by mc29 avian leukosis virus. tat was hardly detectable in tumor tissue of control and dexamethasone-treated chickens, but it was induced by glucagon to levels which were significant although very low when compared to those in host liver or the ... | 1975 | 337 |
| characteristics of two new reticuloendotheliosis virus isolates of turkeys. | reticuloendotheliosis (re) virus strains mn81 and mn67 isolated from epiornithics of re in turkeys were partially characterized. strains mn81 and mn67 replicated in chicken embryo fibroblast,duck embryo fibroblast and turkey embryo-fibroblast cultures and produced syncytial cytopathic effects in duck embryo fibroblast and turkey embryo fibroblast cultures. the virions of mn81 and mn67 measured approximately 100 nm in diameter, resembled re virus strain t, and could be distinguished from avian le ... | 1977 | 15487 |
| purification and properties of spleen necrosis virus dna polymerase. | dna polymerase was purified to apparent electrophoretic homogeneity from virions of spleen necrosis virus (snv). (snv is a member of the reticuloendotheliosis group of avian ribodeoxyviruses). the snv dna polymerase appears to consist of a single polypeptide with a molecular weight of 68,000. the snv dna polymerase has a preference for mn2+ for dna synthesis with an rna template and mg2+ for dna synthesis with a deoxyribohomopolymer template. at the optimum concentrations of divalent cation, the ... | 1975 | 51934 |
| characterization of endogenous rna-directed dna polymerase activity of reticuloendotheliosis viruses. | reticuloendotheliosis viruses (rev) contain an endogenous rna-directed dna polymerase activity. the endogenous dna polymerase activity can be elicited in purified preparations of rev by treatment with nonionic detergents. the enzyme activity has a strong preference for manganous ions. therefore, appreciable endogenous dna polymerase activity can be demonstrated only if the reaction mixture contains appropriate concentrations of manganous ions. enzyme activity can be inhibited by pretreatment wit ... | 1975 | 51936 |
| testing and management of a specific pathogen free chicken flock with special reference to avian leukosis virus infections. | | 1975 | 52293 |
| intracellular restriction on the growth of induced subgroup e avian type c viruses in chicken cells. | subgroup e avian type c viruses produced by bromodeoxyuridine-treated 100 x 7, line 7, or line c chicken cells were restricted in their intracellular growth on k28 chicken cells but not on line 15 chicken cells. cells from embryos of line 15 chickens bred with k28 chickens did not restrict the growth of the subgroup e induced leukosis viruses (ilvs). this result indicates that the phenotype for the intracellular restriction of the growth of subgroup e ilvs found in k28 cells is recessive. long-t ... | 1976 | 58079 |
| tumor growth and antibodies after rsv-challenge in normal chickens and in chickens congenitally infected with avian leukosis virus. | normal chickens and chickens congenitally infected with an avian leukosis virus (alv) of antigenic subgroup a were challenged with strains of rous sarcoma virus (rsv) of two different antigenic subgroups (b and c) and tumor induction and growth as well as humoral antibody to viral envelope antigen (vea) and tumor-specific surface antigen (tssa) were measured. there was no effect of congenital alv infection on rsv tumor incidence or latent period but the growth rate and size of the tumors were mu ... | 1977 | 67140 |
| comparative study of three methods for detecting avian leukosis viruses. | this investigation was designed to compare detection limits for avian leukosis viruses after infection of chicken fibroblasts with decimal dilutions of rous-associated virus type 1 (rav-1). at 5, 9, 14, and 19 days postinfection, cells were examined for group-specific (gs) antigens by microtiter complement-fixation (cf) tests for avian leukosis viruses and by radioimmunoassays (ria) for the major gs antigen having a molecular weight of 27,000 (p27). culture fluids, collected at the same time per ... | 1977 | 68003 |
| assay of noninfectious fragments of dna of avian leukosis virus-infected cells by marker rescue. | a marker rescue assay of noninfectious fragments of avian leukosis virus dnas is describe. dna fragments were prepared either by sonication of ecori-digestion of dnas of chicken cells infected with wild-type rous sarcoma virus, with a nontransforming avian leukosis virus, and with a mutant of rous sarcoma virus temperature sensitive for transformation. recipient cultures of chicken embryo fibroblasts were treated with noninfectious dna fragments and infected with temperature-sensitive mutants of ... | 1977 | 68125 |
| avian retrovirus-induced surface antigens and their cross-reactivity with chemically-transformed cells and primary embryonic cells of japanese quails. | by 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 ... | 1977 | 72738 |
| marker rescue of endogenous cellular genetic information related to the avian leukosis virus gene encoding rna-directed dna polymerase. | endogenous cellular genetic information related to the avian leukosis virus gene encoding rna-directed dna polymerase was studied, using a marker rescue assay to detect biological activity of subgenomic fragments of virus-related dnas of uninfected avian cells. recipient cultures of chicken embryo fibroblasts were treated with sonicated dna fragments and were infected with a temperature-sensitive mutant of rous sarcoma virus that encoded a thermolabile dna polymerase. wild-type progeny viruses w ... | 1978 | 76685 |
| isolation and characterization of a virus-specific ribonucleoprotein complex from reticuloendotheliosis virus-transformed chicken bone marrow cells. | chicken bone marrow cells transformed by reticuloendotheliosis virus (rev) produce in the cytoplasm a ribonucleoprotein (rnp) complex which has a sedimentation value of approximately 80 to 100s and a density of 1.23 g/cm3. this rnp complex is not derived from the mature virion. an endogenous rna-directed dna polymerase activity is associated with the rnp complex. the enzyme activity was completely neutralized by anti-rev dna polymerase antibody but not by anti-avian myeloblastosis virus dna poly ... | 1978 | 81319 |
| comparison of the rna-dependent dna polymerase of an endogenous avian leukosis virus to the polymerase of an exogenous avian leukosis virus. | rna-dependent dna polymerases from rous-associated virus-o and avian myeloblastosis virus were partially purified by affinity chromatography and compared to each other. the enzymes are indistinguishable in the immunoglobulin inhibition test and by several enzymological criteria, such as optimum curves for the concentrations of mg2+, k+, h+; monophasic lineweaver-burk plot for dttp and biphasic lineweaver-burk plot for dgtp. in thermal inactivation studies a small difference can be observed, sugg ... | 1978 | 81774 |
| demonstration of chicken fetal antigen (cfa) on normal splenic lymphocytes, marek's disease lymphoblastoid cell lines and other neoplasms. | chicken fetal antigen (cfa) was detected on normal splenic lymphocytes and a direct relationship was observed between the percentage of cfa-positive cells and the age of the donor. the fetal antigen was also detected on lymphoblastoid tumor cells and cell lines induced by known avian oncogenic viruses (marek's disease virus and avian leukosis virus), and on spontaneously occurring adenocarcinoma cells. the fetal antigen appears to be distinct from marek's disease tumor-associated surface antigen ... | 1979 | 90665 |
| v-15b, an allele of chickens for the production of a noninfectious avian leukosis virus. | | 1979 | 91257 |
| low freqeuncy production of recombinant subgroup e avian leukosis viruses by uninfected v-15b chicken cells. | | 1979 | 91259 |
| pheasant virus dna polymerase is related to avian leukosis virus dna polymerase at the active site. | the dna polymerase from amherst pheasant virus (apv), a member of the pheasant virus species of retroviruses, was compared to the dna polymerases of avian leukosis viruses (alv) and a reticuloendotheliosis virus (spleen necrosis virus (snv)). immunoglobulin inhibition tests and competition immunoassays showed that apv and alv dna polymerases are closely related at their active sites. the determinants common to their active sites are not shared by snv dna polymerase. bu using a species-specific r ... | 1979 | 94361 |
| chicken leukosis virus genome sequences in dna from normal chick cells and virus-induced bursal lymphomas. | genome sequences of two recent field isolates of avian leukosis viruses in the dna of normal and neoplastic chicken cells were studied by dna-rna hybridization under conditions of dna excess. comparisons were made between 60-70s rna from these viruses and that of a chicken endogenous type c virus (rav-0), and of a series of "laboratory" leukosis and sarcoma viruses, by competitive hybridization analysis. a minimum of 18% of the genome sequences of both alv isolates detected in dna from lymphomas ... | 1975 | 164291 |
| neoplastic response of the avian liver to host infection with strain mc29 leukosis verus. | studies were made on the oncogenic response of 3086 young chicks to i.v. inoculation of mc29 avian leukosis virus from blood plasma of previous-passage birds or the supernatant fluid of cultures of chick embryo cells infected with strain mc29. among the large variety of neoplasms of other tissues previously described, there occurred a high incidence of primary growths of the liver. pathomorphology of the growths frequently differed greatly in both different hosts and the same bird, but some unif ... | 1975 | 165881 |
| phenotypic mixing test to detect and assay avian leukosis viruses. | a phenotypic mixing (pm) test for detecting and assaying avian leukosis viruses (alv) of the a, b, c, and d subgroups is described. an alv and rous sarcoma virus rsv-0) are phenotypically mixed by co-cultivating on c/o (cells susceptible to all subgroups of alv) cells for a certain period. then the rsv with the new virus property is assayed on c/e cells (cells resistant to infection with subgroup e leukosis/sarcoma viruses). the test is relatively simple and rapid, and its results are unequivoca ... | 1975 | 168850 |
| infectious dna from cells infected with rous sarcoma virus, reticuloendotheliosis virus or rous-associated virus-o. | we have described an efficient and quantitative assay for infectious dna of the avian ribodeoxyviruses and have applied this method to study the possible existence of infectious viral dnas in uninfected cells. infectious dna from cells infected with rsv or rev consisted of a single unit of dna with a specific infectivity of 10(-5)-10(-6). the minimum molecular weight of rsv dna required for infection of chicken cells was about 6 million, while the minimum molecular weight of infectious rev dna w ... | 1975 | 169004 |
| oncogenesis by marek's disease herpesvirus in chickens lacking expression of endogenous (gs, chick helper factor, rous-associated virus-o) and exogenous avian rna tumor viruses. | chickens free of exogenous avian leukosis virus (alv) infection, replicating endogenous alv (rous-associated virus-o), gs antigen, and chick helper factor were fully susceptible to induction of marek's disease (md) by alv-free md viruses. dual infection with rous-associated virus-2 and md virus did not significantly alter the character of the md lesions. thus exogenous alv infection was not requisite for md virus-induced oncogenesis. although participation of endogenous rna tumor virus genes in ... | 1975 | 169364 |
| low oncogenic potential of avian endogenous rna tumor virus infection or expression. | of chickens either spontaneously producing or exogenously infected in ovo with rous-associated virus, type o (rav-o), an endogenous virus of the chicken, only 1 died with lymphoid leukosis (ll), the most common neoplasm associated with the leukosis-sarcoma virus group. because the chickens were not kept in strict isolation, it could not be assumed that the one ll was induced by rav-o. in contrast, rav-1-infected chickens from the same lines had a high incidence of ll and other neoplasms. over 80 ... | 1975 | 169382 |
| plaque assay of avian sarcoma viruses using casein. | the caseinolytic activity of several strains of rous sarcoma virus (rsv), conditional and nonconditional mutants of rsv, and nontransforming avian leukosis viruses was investigated. only those viruses capable of transforming chick fibroblasts in vitro induced lysis of casein incorporated into an agar overlay. lysis produced distinct clear areas in the turbid casein-agar gel which allowed a quantitative "plaque" assay of cell transformation. casein plaque formation could not be separated from mor ... | 1975 | 169393 |
| a structural change of the plasma membrane induced by oncogenic viruses: quantitative studies with the freeze-fracture technique. | in bhk21 hamster cells a significant increase in density of intramembranous particles occurs in freeze-fractured plasma membranes after transformation by hamster sarcoma and polyoma viruses. a similar change has been observed in chick embryo cells infected and transformed by a mutant of rous sarcoma virus thermosensitive for transformation, at both permissive and nonpermissive temperatures. there is also an increase in particle density in chick cells infected with the rous-associated avian leuko ... | 1975 | 169526 |
| responses of isolator-derived japanese quail and quail cell cultures to selected animal viruses. | thirteen oncogenic and necrotizing animal viruses were assayed in life sciences, inc. (lsi)-specific pathogen-free japanese quail and lsi-specific pathogen-free chicken embryo cell cultures. nine viruses produced similar titers in the quail and chicken cell systems, whereas four viruses showed significantly higher titers in chickens. young japanese quail and chickens were inoculated with five selected avain viruses and maintained in stainless-steel isolators. comparable responses were noted in q ... | 1975 | 172527 |
| expression of endogenous alv antigens and susceptibility to subgroup e alv in three strains of chickens (endogenous avian c-type virus). | | 1976 | 174298 |
| lack of correlation between marena tumor induction and expression of endogenous avian rna tumor virus genome. | infection with marek's disease virus (mdv) and subsequent tumor development failed to induce the expression of endogenous avian rna tumor virus genome in line-15i and line-7 chickens which lacked such expression at 1 day of age. titers of avian leukosis virus (alv) group-specific (gs) antigen detected by the cofal test and expression of chick helper factor (chf) activity remained relatively constant in birds which expressed these genome functions at hatching time. endogenous alv belonging to the ... | 1976 | 175029 |
| experimental models for dna-rna viral interactions: a brief review. | evidences that demonstrate or imply the occurrence of dna-rna viral interactions in man and animals are reviewed. the concurrent presence of two dissimilar oncogenic viruses influenced responses both in vivo and in vitro. cell-mediated immune responses to marek's disease herpesvirus were altered in specific-pathogen-free chickens inoculated as embryos with an avian leukosis virus. the possible roles of immunological factors in the pathogenesis and control of tumor development associated with dna ... | 1976 | 175924 |
| antibody response to related leukosis viruses induced in chickens tolerant to an avian leukosis virus. | white leghorn chickens congenitally infected with a subgroup a avian leukosis virus alv-f42 were challenged at various ages with the serologically related subgroup a avian leukosis viruses (alv) rav-1, rav-3, and rav-5 and their antibody responses and viremic status determined. birds given injections of rav-1 failed to produce neutralizing antibody to any of the pseudotype sarcoma viruses of the various alv, whereas many birds challenged with rav-3 or rav-5 produced neutralizing antibody directe ... | 1976 | 176386 |
| rate of virus-specific rna synthesis in synchronized chicken embryo fibroblasts infected with avian leukosis virus. | the rate of avian leukosis virus (alv)-specific rna synthesis has been examined in bot- uninfected and alv-infected synchronized chicken embryo fibroblasts. rna from cells labeled for 2h with [3h]uridine was hybridized with avian myeloblastosis virus poly(dc)-dna, and the hybridized rna was analyzed with poly(i)-spephadex chromatography. approximately 0.5% of the rna synthesized in alv-infected cells was detected as virus specific, and no more than a twofold variation in the rate of synthesis wa ... | 1976 | 176421 |
| lack of infectivity of the endogenous avian leukosis virus-related genes in the dna of uninfected chicken cells. | the infectivity of the avian leukosis virus-related genes in the dna of four genetically distinct types of chicken cells was determined. infectious dna of rous-associated virus-o(rav-o) was obtained from v- chicken cells which were experimentally infected with rav-o and from v+tvbs chicken cells, which spontaneously produced rav-o and were sensitive to exogenous rav-o infection. however, infectious dna of rav-o was not obtained from uninfected v- chicken cells or from v+tvbr chicken cells, which ... | 1976 | 176424 |
| localization of the major group-specific protein (p27) of avian tumor viruses by immunofluorescence in chicken cells and tissues. | an immunofluorescence technique was developed for the major group-specific (gs) p27 antigen of avian type c viruses. the localization of this antigen virus-infected in chick embryo fibroblasts was perinuclear, intracytoplasmic and at the cell surface in the majority of the cells, while it was at the cell surface only in some of the cells. no antigen was found in the nucleus. when chickens were experimentally infected with rav-1 or a wild-strain avian leukosis virus (of subgroup a), the viral gs ... | 1975 | 178623 |
| a lymphoblastoid cell line dually infected with marek's disease virus and avian leukosis virus. | | 1976 | 180969 |
| morphological changes in chick embryo cell cultures induced by avian leukosis viruses. | morphological alterations were observed after 5-15 serial passages of cells infected with three different strains of avian leukosis virus: ok 10, an a subgroup virus isolated from a natural infection; rav-1, an established laboratory strain of the a subgroup, and rav-2, a laboratory strain of the b subgroup. the infected cells had a prolonged lifespan of approximately 28 passages, compared to 14 passages for control cells. however, the altered cells had none of the attributes of transformed cell ... | 1975 | 181344 |
| [dependence of the formation of antibodies against avian leukosis virus on specific cell sensitivity]. | | 1976 | 182447 |
| chicken egg yolk enhances focus formation by subgroup b, c and d rous sarcoma viruses. | focus formation by rous sarcoma virus (rsv) was significantly enhanced when virus was incubated with the saline fraction of chloroform extracted chicken egg yolk, prior to infecting chicken embryo cells. the enhancement was restricted to members of rsv subgroups b, c and d and was proportional to yolk dilution. subgroup a virus was never affected. in all, 108 yolk samples from specific pathogen free chickens were investigated. of these 78 to 97% stimulated focus formation. rsv(rav-50) of subgrou ... | 1976 | 182909 |
| avian leukosis viruses of different subgroups and types isolated after passage of rous sarcoma virus-rous-associated virus-0 in cells from different ring-necked pheasant embryos. | avian leukosis viruses of subgroups a and f (rav-a and rav-f) arose at a low rate after passage of rous sarcoma virus-rous-associated virus-0, which is subgroup e, in cells from ring-necked pheasant embryos. in cells of two embryos, all of the viruses isolated after virus passage were rav-f. however, in cells of a third embryo, both rav-a and rav-f were isolated. in addition, there sometimes were type-specific differences among the different isolates of rav-a and rav-f from the cells of single e ... | 1976 | 183006 |
| virus-infected avian cell lines established in vitro. | four virus-infected avian cell lines have been established in culture. two of these lines, infected with bai strain a virus, liberate only small quantities of virus in the culture fluid. the cells retain the ability to induce myeloblastic leukemia when inoculated i.v. into 1- to 2-day-old chicks, but do so less efficiently than freshly obtained myeloblasts. these cells do not appear to be transplantable, since the disease produced is characterized by the presence of myeloblasts that liberate lar ... | 1976 | 184918 |
| hypergammaglobulinemia in chickens congenitally infected with an avian leukosis virus. | significantly elevated (2- to 5-fold higher than controls) serum levels of igg were found in chickens congenitally infected with f42 strain of avian leukosis (alv-f42) a subgroup a avian leukosis virus (alv). a further increase in igg levels in congenitally infected birds was found to be induced by injection of influenza virus in complete freund's adjuvant(cfa). serum immunoglobulin m (igm) levels were not significantly elevated in alv congenitally infected chickens except in those animals that ... | 1976 | 185293 |
| temperature-sensitive mutants of avian sarcoma viruses: genetic recombination between multiple or coordinate mutants and avian leukosis viruses. | | 1976 | 185803 |
| target cells for transformation with avian leukosis viruses. | | 1976 | 188724 |
| 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 ... | 1977 | 189085 |
| oncogenicity of avian leukosis viruses of different subgroups and of mutants of sarcoma viruses. | leukosis viruses of seven subgroups were tested for oncogenicity in chickens susceptible to virus infection and to development of lymphoid leukosis (ll) tumors. all subgroup a viruses and the subgroup b virus tested produced a high incidence of ll and other related neoplasms. viruses of subgroup c and rav-61 of subgroup f produced a low level of ll. the rav-50 of subgroup d produced osteopetrosis. in these tests, the viruses of subgroup e and g and one virus of subgroup f were not pathogenic, po ... | 1977 | 191400 |
| contact transmission of avian leukosis virus. | intravenous inoculation of four age groups of white leghorn chicks with alv-f42, a group a field strain of avian leukosis virus (alv), indicated that persistent tolerant infection could be induced as late as 2 weeks post hatch, though most birds responded with neutralizing antibody. contact infection by environmental exposure to alv was 100% effective in newly hatched and 28-day-old chicks. all contact-infected birds responded immunologically after transient viremia. a follow-up of immune birds ... | 1977 | 191622 |
| 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 ... | 1977 | 194849 |
| complementation rescue of rous sarcoma virus from transformed mammalian cells by polyethylene glycol-mediated cell fusion. | polyethylene glycol (peg) is effective as a fusing agent for the rescue of virus from rous sarcoma virus-transformed mammalian cells. the procedure of peg-mediated rescue of virus from virogenic cell lines is described, and the technique is compared with that of sendai virus-mediated rescue. virus may be rescued quantitatively from virogenic cell lines by plating mitomycin c-killed transformed mammalian cells with chicken embryo cells, treating the monolayers with 50% peg and overlaying the mono ... | 1977 | 196098 |
| genetic variation in the rna transcripts of endogenous virus genes in uninfected chicken cells. | uninfected cells from two different phenotypes of chicken embryos express significant amounts of endogenous viral information, though they do not produce virus particles. cells of the phenotype gs(+)chf(+) are positive for both group-specific (gs) antigens and chicken helper factor (chf) activity, whereas cells of a second phenotype, gs(l)chf(+)(h(e)), demonstrate noncoordinate expression of these two viral activities (very low amounts of gs antigens, but extremely high helper activity). rna fro ... | 1977 | 198586 |
| viral protein synthesis by tissues from avian leukosis virus-infected chickens. i. susceptible chickens infected after hatching. | | 1977 | 199668 |
| nucleotide sequences derived from pheasant dna in the genome of recombinant avian leukosis viruses with subgroup f specificity. | recombination between viral and cellular genes can give rise to new strains of retroviruses. for example, rous-associated virus 61 (rav-61) is a recombinant between the bryan high-titer strain of rous sarcoma virus (rsv) and normal pheasant dna. nucleic acid hybridization techniques were used to study the genome of rav-61 and another rav with subgroup f specificity (rav-f) obtained by passage of rsv-rav-0 in cells from a ring-necked pheasant embryo. the nucleotide sequences acquired by these two ... | 1977 | 199737 |
| contrasting characteristics of marek's disease herpesvirus isolated from chickens with and without avian leukosis virus infection. | marek's disease herpesvirus (mdhv) isolated from chickens free of naturally occurring avian leukosis virus (alv) infection produced characteristic foci in both chicken embryo fibroblast (cef) and chicken kidney cell (ckc) cultures. mdhv-a, which was extracted from the feather follicle epithelium of chickens naturally infected with alv, did not induce cytologic changes in cef cultures, but did cause focus formation in ck cultures. alv was detected in mdhv-a, but not in mdhv preparations. mdhv-a ( ... | 1978 | 204600 |
| identification of a transformation-specific protein induced by a rous sarcoma virus. | using antisera obtained from rats bearing schmidt-ruppin strain rous sarcoma virus-induced tumors, we have idnetified a protein with an apparent molecular weight of 56,000 daltons and an isoelectric point of 6.3 in extracts of chick embryo fibroblasts transformed by a wild-type nondefective rous sarcoma virus (schmidt-ruppin strain). this protein was not found in cells infected by trnasformation-defective mutants with either a partial or complete deletion of the src gene, nor in cells infected b ... | 1978 | 207435 |
| ok 10 virus, an avian retrovirus resembling the acute leukaemia viruses. | the ok 10 virus complex was isolated from a liver tumour of a chicken which, as an embryo, had been inoculated intravenously with a field isolate of an avian leukosis virus. the ok 10 virus complex contains at least two viruses: the interference assay and serum neutralization test indicate that the helper virus belongs to subgroup a. one of the viruses, ok 10 v, induces distinct foci in chick embryo cells under agar overlay and cells from the foci form colonies in soft agar. these properties all ... | 1978 | 211198 |
| genetic analysis of the defectiveness in strain mc29 avian leukosis virus. | | 1978 | 211711 |
| linkage of the endogenous avian leukosis virus genome of virus-producing chicken cells to inhibitory cellular dna sequences. | the endogenous avian leukosis virus genome of uninfected virus-producing(v+) chicken embryo fibroblasts appears to be inefficiently transcribed and is noninfectious in transfection assays of high molecular weight dna. we previously proposed that the endogenous virus genome was linked to a cis-acting control element which inhibited its transcription and, consequently, interfered with transfection by endogenous viral dna. we now report that dna of uninfected v+ cells is infectious at a low level w ... | 1978 | 214243 |
| enhanced oncornavirus expression in marek's disease tumors from specific-pathogen-free chickens. | an oncornavirus was recovered from cell cultures of kidney tumors from specific-pathogen-free chickens inoculated with marek's disease herpesvirus (mdhv). the mdhv inoculum was free of infectious avian leukosis virus (alv). direct examination of a variety of tissues from mdhv-inoculated chickens demonstrated increased levels of alv-specific rna compared to tissues from diluent-inoculated (control) chickens. dna from cultured kidney tumor cells annealed to an alv complementary dna probe at the sa ... | 1979 | 216833 |
| persistence of avian oncoviruses in chicken macrophages. | inoculation of avian oncoviruses into 1- to 2-month old chickens led to a rapid production of antiviral humoral antibodies. under these conditions it was found that avian leukosis viruses are sequestered in macrophages of peripheral blood, in which they can persist for a long period of time (up to about 3 years). in contrast, avian sarcoma viruses were never found in macrophages from chickens during the progression of sarcomas or after regression of the tumors. | 1979 | 217827 |
| 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 ... | 1979 | 221927 |
| response of hemopoietic cells to avian acute leukemia viruses: effects on the differentiation of the target cells. | chicken bone marrow cells were infected with three avian acute leukemia viruses (alv)--avian myeloblastosis virus (amv), myelocytomatosis virus strain mc29 and mill hill 2 virus (mh2)--and then cultured in agar in the presence of conditioned medium. under these conditions, it was found that very few cells served as target cells for these three viruses. density gradient separation showed that alv target cells were found primarily in the light density fractions and might be represented by cells co ... | 1979 | 222465 |
| lymphomas resembling lymphoid leukosis in chickens inoculated with reticuloendotheliosis virus. | chickens inoculated as embyros or at hatching with the chick syncytial strain of reticuloendotheliosis virus developed a high incidence of lymphoid neoplasms between the 17th and 43rd weeks of age, involving principally the liver and bursa of fabricius. on the basis of organ distribution, latent period, pathology and surface igm production, the lymphomas closely resembled those of lymphoid leukosis. one inoculated chicken developed a myxosarcoma. no tumors were observed in uninoculated controls. ... | 1979 | 222694 |
| failure to confirm evidence for a nonvirion tumor-specific surface antigen in avian retrovirus-transformed cells. | triton x-100 or nonidet p40-deoxycholate extracts of [3h]fucose-labeled rous sarcoma virus-transformed chick embryo fibroblasts were examined by indirect immunoprecipitation for the presence of a tumor-specific neoantigen of 100,000 daltons. extracts were incubated with immune igg from rous tumor-sensitized chickens, and the resultant antigen-antibody complexes were precipitated with rabbit antichicken igg and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. radioactivity a ... | 1979 | 225505 |
| avian sarcoma virus-transformed quail clones defective in the production of focus-forming virus. | quail embryo fibroblasts were infected at low multiplicity with avian sarcoma virus, and transformed cells were selected by their ability to form colonies in agar. five clones that failed to produce focus-forming virus were examined for (i) intactness of the integrated proviral dna, (ii) intracellular viral rna production, (iii) intracellular viral antigen production, (iv) production of virus particles, and (v) rescue of a functional src gene and of parental host range determinants by superinfec ... | 1979 | 225511 |
| gs, an allele of chickens for endogenous avian leukosis viral antigens, segregates with ev 3, a genetic locus that contains structural genes for virus. | gs is an allele of chickens for the expression of endogenous avian leukosis virus-related core (gs) and envelope (chf) antigens. progeny of a genetic cross in which gs was segregating were analyzed for endogenous viral dna as well as for the expression of endogenous viral antigens. viral genetic information was identified by cleavage of embryo dna with restriction endonucleases, electrophoretic separation of the resulting fragments, and identification of bands containing viral sequences by hybri ... | 1979 | 225563 |
| in vitro replication of infectious bursal disease virus in established lymphoid cell lines and chicken b lymphocytes. | the in vitro susceptibility of chicken lymphocytes to a wild strains of infectious bursal disease virus was investigated by using immunofluorescence and virus assays as infection criteria. a variety of marek's disease lymphoblastoid cell lines, all of thymus (t-cell) origin, were refractory to virus exposure. however, a bursa (b-cell)-derived lymphoblastoid cell line from an avian leukosis virus-induced tumor was highly susceptible. viral antigen appeared in the cytoplasm of 20 to 30% of the cel ... | 1979 | 227789 |
| endogenous viral genes are non-essential in the chicken. | dna sequences homologous to the genomes of type c retroviruses are widespread among vertebrates. ten genetic loci containing endogenous viral dna sequences have been documented in the white leghorn chicken alone. six of these genetic loci are associated with the production of virus or of viral proteins in embryonic fibroblasts (refs 2--4, and s.m.a., l, b. crittenden and e.g.b., in preparation) and one of the loci may be expressed in the erythroblasts of 5-day-old embryos. the abiquitous presenc ... | 1979 | 228201 |
| an evaluation of methods for eradication of avian leukosis virus from a commercial breeder flock. | two trials were conducted to determine whether lymphoid leukosis virus (llv) could be eradicated from chicken breeder stocks in one generation. dams were selected as potentially virus-free parents on the basis of negative tests for virus in progeny embryos (trial 1) or in vaginal-cloacal swabs (vcs) (trial 2) of the dams. in trial 1, 8 of 12 groups of chickens hatched from selected breeders remained free of llv infection through 36 weeks of life. in trial 2, vcs appeared to be more efficient in ... | 1979 | 230807 |
| immune response to avian leukosis virus infection in chickens: sequential expression of serum immunoglobulins and viral antibodies. | | 1979 | 232865 |
| [avian leukosis viruses (author's transl)]. | | 1979 | 233053 |
| a reexamination of humoral tolerance in chickens congenitally infected with an avian leukosis virus. | in a reexamination of congenital infection of chickens with alv, one of the classical models of immunologic tolerance, we were unable to demonstrate that there was any evidence suggesting humoral immune reactivity to the infecting virus. in alv-f42 congenitally infected birds that have a persistent viremia and no neutralizing antibody detectable by conventional means, we could find no evidence of host igg deposits in the kidneys, nor any suggestion of renal pathology, or damage. in addition, att ... | 1979 | 448076 |
| viral protein sythesis by tissues from avian leukosis virus-infected chickens. ii. effect of passive neutralizing antibody in normal and agammaglobulinaemic chickens. | synthesis in vitro of avian leukosis virus (alv) group (gs proteins, p27 and p12, by various tissues from chickens infected within a few days after hatching was studied by means of autoradiography of immunoelectrophoretic patterns. viral protein was synthesized in all tissues of chicks examined between days 18 and 50 of age after which time liver, kidney, bursa, thymus, and spleen became negative. the lung and genital organs of the chicks, however, continued to synthesize viral protein up to 100 ... | 1979 | 500117 |
| chemical carcinogen-induced transplantable fibrosarcomas in histocompatible chickens. i. incidence of tumor induction in normal and bursectomized chickens. | transplantable fibrosarcomas were developed in two b-locus-defined chicken strains from primary tumors induced by im injection of 2 mg 7,12-dimethylbenz[a]anthracene in 0.1 ml dimethyl sulfoxide into 1- to 2-week-old chicks. viruses were not important factors in transmission of these tumors as evidenced by 1) transplantability only within the chicken strain of origin, 2) lack of evidence for a filterable agent, 3) maintenance of donor karyotypic characteristics upon transplantation, 4) lack of d ... | 1976 | 826648 |
| phytohemagglutinin-induced leukocyte blastogenesis in normal and avian leukosis virus-infected chickens. | | 1976 | 991279 |
| the expression and localization of surface neoantigens in transformed and untransformed cultured cells infected with avian tumor viruses. | the presence and localization of neoantigens induced in cultured cells, infected or transformed with avian tumor viruses (atv), were studied ultrastructurally on carbon platinum replicas of cell surfaces. the use of antibody, labeled with hemocyanin molecules, provided sensitive detection and analysis of cell surface antigen distribution. the subgroup-specific antigens of the viral envelope were found in considerable amount in the plasma membranes of atv-infected chick embryo fibroblasts. the di ... | 1976 | 1256061 |
| activation of the c-myb locus is insufficient for the rapid induction of disseminated avian b-cell lymphoma. | we have previously reported that infection of 9- to 13-day-old chicken embryos with rav-1 results in rapid development of a novel b-cell lymphoma in which proviral insertion has activated expression of the c-myb gene (e. pizer and e. h. humphries, j. virol. 63:1630-1640, 1989). the biological properties of these b-cell lymphomas are distinct from those associated with the b-cell lymphomas that develop following avian leukosis virus proviral insertion within the c-myc locus. in an extension of th ... | 1992 | 1309260 |
| art-ch, a new chicken retroviruslike element. | a 3' region of a previously unknown retroviruslike element named art-ch (avian retrotransposon from chicken genome) was obtained in the course of polymerase chain reaction-mediated cloning of avian leukosis virus long terminal repeats (ltrs) from dnas of infected chicken cells. about 50 copies of art-ch are present in the genome of chickens of different breeds. art-ch is not found in dna of quails, ducks, turkeys, or several other birds tested. the art-ch element is about 3 kb in size, including ... | 1992 | 1310773 |
| complete nucleotide sequence of a highly infectious avian leukosis virus. | | 1992 | 1311072 |
| carg, ccaat, and ccaat-like protein binding sites in avian retrovirus long terminal repeat enhancers. | a strong enhancer element is located within the long terminal repeats (ltrs) of exogenous, oncogenic avian retroviruses, such as rous sarcoma virus (rsv) and the avian leukosis viruses. the ltrs of a second class of avian retroviruses, the endogenous viruses (evs), lack detectable enhancer function, a property that correlates with major sequence differences between the ltrs of these two virus groups. despite this lack of independent enhancer activity, we previously identified sequences in ev ltr ... | 1992 | 1312613 |
| sporadic congenital transmission of avian leukosis virus in hens discharging the virus into the oviducts. | the efficacy of the albumen test for infectious avian leukosis virus (alv) was examined in detecting congenitally transmitting hens. seventy-three white leghorn non-viremic hens with antibody to alv were used. eleven of the hens shed infectious alv into their egg albumen, whereas only 7 of the 11 alv-positive hens shed alv antigens. the egg albumen test for infectious alv was shown to be more effective in detecting the congenitally transmitting hens than that for alv antigens. then, twenty of th ... | 1992 | 1313708 |
| developments in avian leukosis research. | infection by exogenous avian leukosis viruses (alvs) causes economic loss from neoplastic mortality and from impaired performance of subclinically infected chickens. this paper reviews progress in research related to natural infection and its control. subgroup a alvs causing lymphoid leukosis are the most common viruses in the field, but variant viruses can arise and cause losses. in israel in recent years, epidemic outbreaks of haemangiosarcomas caused by a virus of unusual cytopathogenicity ha ... | 1992 | 1318466 |
| a transgene, alv6, that expresses the envelope of subgroup a avian leukosis virus reduces the rate of congenital transmission of a field strain of avian leukosis virus. | a major mode of transmission of avian leukosis virus (alv) is from a dam that is viremic with and immunologically tolerant to alv, through the egg to the progeny. the authors have produced a line of chickens transgenic for a defective alv provirus that expresses envelope glycoprotein, but not infectious virus, and is very resistant to infection with subgroup a alv. in the present experiment the authors sought to prevent or reduce congenital transmission by mating viremic-tolerant hens to males c ... | 1992 | 1319049 |
| nonrandom integration of retroviral dna in vitro: effect of cpg methylation. | we have developed a pcr-based system that allows us to assess the relative frequency of use of specific bases as targets for the avian leukosis virus in vitro integration system. using this system, we tested the effect of 5-methylation of cytosine in runs of cpg on the distribution of integration target sites. we found that the distribution of preferred integration sites was not uniform along the target dna; rather, there was a distinct and reproducible pattern of frequently used sites. this pat ... | 1992 | 1319063 |
| proteolysis in the maturation of avian retroviruses does not require calcium. | after budding from the plasma membrane, retrovirus particles undergo a process of maturation, which includes changes in morphology caused by several proteolytic cleavages of the precursor of the internal structural proteins, products of the gag gene. cleavage is mediated by the viral protease, pr. the fact that in most systems cleavage appears to occur only after assembly is complete, suggests that pr may become enzymatically active as a consequence of release of the virion from the cell. using ... | 1992 | 1322601 |
| association of the major histocompatibility complex with avian leukosis virus infection in chickens. | 1. association of the b blood group, the major histocompatibility complex (mhc) in chickens, with avian leukosis virus (alv) infection shown by shedding of group-specific (gs) antigen was studied in an australorp line selected for short oviposition interval to improve egg production. three haplotypes (b8a, b9a and b21) were segregating in this line at frequencies of 66.7, 15.6 and 17.8%, respectively, averaged over three generations. 2. the relative risk (odds ratio) of a hen becoming a gs-antig ... | 1992 | 1322760 |
| packaging cells for avian leukosis virus-based vectors with various host ranges. | using our previously described haydée semipackaging cell line (f. l. cosset, c. legras, y. chebloune, p. savatier, p. thoraval, j. l. thomas, j. samarut, v. m. nigon, and g. verdier, j. virol. 64:1070-1078, 1990) which produces avian leukosis virus gag and pol proteins, we have constructed packaging cells with subgroups b, c, and e envelope specificities. this allows us to produce helper-free avian leukosis virus particles carrying the lacz reporter gene and the a, b, c, or e subgroup specificit ... | 1992 | 1323718 |
| a note on propagation of avian leukosis virus in chick embryos. | | 1978 | 210113 |
| microinjection analysis of envelope-glycoprotein messenger activities of avian leukosis viral rnas. | virion rna from the avian leukosis virus rous-associated virus 2 (rav-2) and poly(a)-containing rnas from rav-2-infected chick embryo fibroblasts were microinjected into fibroblasts transformed by the bryan high-titer strain of rous sarcoma virus (rsv), which is deficient in viral envelope glycoprotein. production of infectious rsv following these injections depended upon the viral envelope-messenger activity of the injected rna. this system constituted a sensitive and rigorous assay system for ... | 1977 | 193109 |
| expression of virion and tumor-specific antigens on the surface of chick embryo cells infected with strain mc29 avian leukosis virus. | the immunological properties of the surface of chick embryo cells infected with strain mc29 avian leukosis virus were investigated by immune electron microscopy in conjunction with antiviral and anticellular immune sera. when samples were taken at sequential times after infection, it was found that cells stained strongly for viral antigen very early after infection. staining reached a minimum 6 to 12 hr after infection and then increased to maximum at 15 hr after infection, remaining at this lev ... | 1976 | 177199 |
| isolation and characterization of viruses from natural outbreaks of reticuloendotheliosis in turkeys. | we have described the in vitro isolation of type-c rna viruses from two outbreaks of a fatal neoplastic disease in turkeys we diagnosed as reticuloendotheliosis. the virus had a density of 1.16 g/ml in sucrose gradients, had a dna polymerase capable of using both endogenous and exogenous (synthetic) templates, and was infectious in vitro for turkey and chick cells. the culture-propagated virus was oncogenic for turkeys. the virus isolates were unrelated to avian leukosis virus and antigenically ... | 1975 | 166189 |
| 5' avian leukosis virus sequences and osteopetrotic potential. | recombinants of rous-associated virus-0 and br21 have been used to localize 5' viral sequences that affect the osteopetrotic potential of avian leukosis viruses. rous-associated virus-0 is a benign subgroup e virus of endogenous origin that does not cause osteopetrosis. br21 is a constructed subgroup e virus with high osteopetrotic potential. 5' sequences that affected osteopetrotic potential resided in an 834-bp region near the 5' ltr. sequence analysis of this region revealed differences betwe ... | 1992 | 1325711 |
| endogenous viral gene distribution in populations of meat-type chickens. | the present study was designed to document the complexity of endogenous viral (ev) genes and seek evidence for their association with production traits in selected and control strains of meat-type chickens. three populations were studied, each consisting of a control strain and one to three strains selected for various production traits. the ev genes were revealed by digesting genomic dna with restriction enzymes and detecting dna fragments on southern blots using radioactive probes from nucleot ... | 1992 | 1326106 |
| in situ expression of helper-free avian leukosis virus (alv)-based retrovirus vectors in early chick embryos. | defective avian leukosis-based vectors expressing the bacterial lacz gene were used as helper-free preparations to infect early stage brown-leghorn embryos. both in toto x-gal staining and dna analysis using southern blot technique were applied to detect virus integration and expression. our results demonstrate a low efficiency of in vitro infection in early stages of embryonic development. southern blot analysis reveals that only 1% of embryonic cells integrate the vector genome after infection ... | 1992 | 1326313 |
| persistence of marek's disease virus in a subpopulation of b cells that is transformed by avian leukosis virus, but not in normal bursal b cells. | previous studies have described an augmentation of avian leukosis virus (alv)-induced lymphoid leukosis in chickens that were coinfected with a serotype 2 marek's disease virus (mdv) strain, sb-1. as a first step toward understanding the mechanism of this augmentation, we have analyzed the tropism of the mdv for the alv-transformed b cell. after hatching, chickens were coinfected with alv and a nonpathogenic strain of mdv, sb-1. seventy primary and metastatic alv-induced lymphomas that developed ... | 1992 | 1326647 |
| effect of avian leukosis virus infection on productivity of layers. | | 1992 | 1327184 |
| a1/ebp: a leucine zipper protein that binds ccaat/enhancer elements in the avian leukosis virus long terminal repeat enhancer. | avian leukosis virus (alv) induces bursal lymphoma in chickens after integration of proviral long terminal repeat (ltr) enhancer sequences next to the c-myc proto-oncogene. labile ltr-binding proteins appear to be essential for c-myc hyperexpression, since both ltr-enhanced transcription and the activities of ltr-binding proteins are specifically decreased after inhibition of protein synthesis (a. ruddell, m. linial, w. schubach, and m. groudine, j. virol. 62:2728-2735, 1988). this lability is r ... | 1992 | 1328681 |
| differentiation of pathogenic and non-pathogenic serotype 1 marek's disease viruses (mdvs) by the polymerase chain reaction amplification of the tandem direct repeats within the mdv genome. | there are no simple, direct methods to reliably distinguish oncogenic serotype 1 marek's disease viruses (mdvs) from their attenuated variants. the present study was an attempt to apply polymerase chain reaction (pcr) to develop a rapid and sensitive assay for the presence of the mdv genome. pcr oligos were chosen to flank the 132-base-pair tandem direct repeats in the serotype 1 mdv genome. the pcr reaction was specific for serotype 1 mdvs, amplifying fragments corresponding to one to three cop ... | 1992 | 1329706 |
| host range of rous sarcoma virus pseudotype rsv(hprs-103) in 12 avian species: support for a new avian retrovirus envelope subgroup, designated j. | the host ranges of the rous sarcoma virus (rsv) pseudotype rsv(hprs-103) of a novel avian leukosis virus (alv), strain hprs-103, and representative rsv pseudotypes of subgroups a to f, have been determined in embryo fibroblasts from 12 avian species. domestic fowl, red jungle fowl, sonnerat's jungle fowl and turkey were susceptible to infection by rsv(hprs-103); ring-necked pheasant, japanese green pheasant, golden pheasant, japanese quail, guinea-fowl, peking duck, muscovy duck and goose were r ... | 1992 | 1331300 |
| myeloid leukaemogenicity and transmission of the hprs-103 strain of avian leukosis virus. | the hprs-103 strain of avian leukosis virus (alv) was isolated recently from meat-type chickens and represents a new envelope subgroup. its oncogenicity has been studied in three meat-type and five leghorn strains of chickens. in the meat-type strains, the virus, following embryonal inoculation, induced an overall incidence of 27% myelocytic myeloid leukosis (myelocytomatosis) and 12% renal adenomas, with long median latent periods. amongst the leghorn lines, these tumors occurred with similar i ... | 1992 | 1331625 |
| oncogene transduction and activation. | this article explains what a transducing virus is, summarizes what is currently known about the origins of transducing viruses, considers the frequency of the generation of transducing viruses, and discusses how transduced oncogenes undergo activation. most of the data come from work with avian leukosis viruses, as research with this group of viruses has set many of the precedents for work on retroviral transduction. | 1992 | 1335931 |
| [erb-b oncogene in human oral squamous cell carcinomas]. | erb-b gene is an oncogene from avian leukosis virus. the carcinogenic capability of erb-b is due to the close similarity of expressional proteins to the epidermal growth factor receptor (egfr). in this study the amplification and the over-expression of erb-b were found in human oral squamous (cell carcinomas by dna and rna dot blot hybridization). results showed that erb-b was correlated with the oral epidermoid tumors but not with group of non-epidermoid tumors in the head and neck region. sout ... | 1992 | 1338545 |
| expression of virally-transduced mouse tyrosinase in cultured chick embryo cells. | a cdna encoding mouse tyrosinase was inserted into a plasmid containing the provirus of a replication competent avian leukosis virus (alv). a viral stock produced from the plasmid was used to infect cultured tyrosinase-negative (ca/ca) unpigmented chick embryo pigment cells. five days after infection many cells were producing very dark discrete pigment granules. cultures of tyrosinase positive, sex linked albino (sal) pigment cells produced no additional pigmentation. white leghorn pigment cells ... | 1990 | 1369250 |