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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 ...197715487
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 ...197881319
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 ...197990665
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 ...1975169364
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 ...1975172527
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 ...1976175029
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 ...1976175924
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 ( ...1978204600
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 ...1979216833
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 ...1978211198
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 ...1977199737
viral protein synthesis by tissues from avian leukosis virus-infected chickens. i. susceptible chickens infected after hatching. 1977199668
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 ...1977198586
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 ...1977196098
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 ...1976185293
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 ...1979230807
immune response to avian leukosis virus infection in chickens: sequential expression of serum immunoglobulins and viral antibodies. 1979232865
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 ...1976184918
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 ...1976182909
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 ...1975181344
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 ...1975178623
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 ...1976176424
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 ...1976176421
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 ...1976176386
expression of endogenous alv antigens and susceptibility to subgroup e alv in three strains of chickens (endogenous avian c-type virus). 1976174298
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 ...1975169004
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 ...1975165881
v-15b, an allele of chickens for the production of a noninfectious avian leukosis virus. 197991257
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 ...197876685
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 ...197768125
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 ...197767140
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 ...197658079
testing and management of a specific pathogen free chicken flock with special reference to avian leukosis virus infections. 197552293
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 ...1975337
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 ...1978214243
integration of different sarcoma virus genomes into host dna: evidence against tandem arrangement and for shared integration sites.cellular dna of 50--54 s was extracted from chicken embryo cells doubly infected with two different avian sarcoma viruses and was analyzed by the infectious dna assay. approximately 80--90% of the transformed foci that were induced by this dna were found to give rise to one kind of avian sarcoma virus only, indicating that most proviral genomes are not integrated in tandem. when the two infecting viruses were varied with respect to multiplicity or time of infection, the initial infecting virus o ...1979221927
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 ...1979500117
phytohemagglutinin-induced leukocyte blastogenesis in normal and avian leukosis virus-infected chickens. 1976991279
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 ...19921313708
detection of avian leukosis virus antigens by the elisa and its use for detecting infectious virus after cultivation of samples and partial characterization of specific pathogen-free chicken lines maintained in this laboratory.an enzyme-linked immunosorbent assay (elisa) for detecting avian leukosis virus (alv) antigens was developed with rabbit anti-alv serum. the elisa detected purified alv of subgroups a and b at a concentration of 0.4 ng/well and about 10(3) infectious units/well estimated by a resistance-inducing factor (rif) test, and antigens in culture fluids from chicken embryo fibroblasts infected with subgroups a, b or e of alv. these results showed that common antigens among the subgroups were detected by ...19911653036
detection of proviral dna and viral rna in various tissues early after avian leukosis virus infection.using molecular biological techniques, a study was made of the tissue tropism of avian leukosis virus (alv) early after infection. two strains of chickens, one with and the other without endogenous viral genes, were infected with alv of subgroup a immediately after hatching; specimens of nine tissues and blood samples were analyzed at various times thereafter. a polymerase chain reaction (pcr), specific to alv subgroup a, was used to detect proviral dna and viral rna. in situ hybridization was u ...19921602809
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. ...1979222694
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 ...1979227789
retroviral expressed hemagglutinin-neuraminidase protein protects chickens from newcastle disease virus induced disease.the hemagglutinin-neuraminidase (hn) gene and the phosphoprotein (p) gene of newcastle disease virus (ndv) were inserted into a replication competent avian leukosis virus vector. the expression of the hn gene from this vector in chick embryo cells has been previously reported. the p gene is also expressed from this vector in chick embryo cells. the retroviruses were used to immunize 4-week-old chickens. birds receiving the virus containing the hn gene developed low levels of serum hi titers and ...19901965848
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 ...1979228201
chronic myocarditis and circulatory syndrome in a white leghorn strain induced by an avian leukosis virus: light and electron microscopic study.specific-pathogen-free white leghorn chickens were inoculated at 1 day of age with avian leukosis virus (alv, rav-1). all chickens in expt. 1, killed 33 or 64 days postinoculation, had focal chronic lymphocytic or lymphoplasmacytic myocarditis. among those held beyond 33 days, eight of 22 developed lesions in the myocardium that resulted in a chronic circulatory syndrome (ccs) typical of right-sided heart failure. chickens in expt. 2 were held for 210 days, and 21% of 125 developed ccs. in expt. ...19902157391
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 ...1979448076
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 ...1976826648
the influence of ev6 on the immune response to avian leukosis virus infection in rapid-feathering progeny of slow- and rapid-feathering dams.endogenous virus (ev) locus ev6 encodes only virus envelope glycoprotein. the influence of ev6 on the immune response to contact infection with hatchmates infected with avian leukosis virus (alv) was compared in replicate hatches. the alv subgroup e-resistant, rapid-feathering (rf) female chickens produced by slow-feathering (sf) and rf dams with and without ev6 were exposed at hatch to hatchmates infected with alv subgroup a (strain rpl-40). the rpl-40 viremia, shedding, and virus neutralizing ...19911656418
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 ...19761256061
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 ...19921309260
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 ...19921310773
3'-azido-3'-deoxythymidine inhibits the replication of avian leukosis virus.we tested the ability of the thymidine analog 3'-azido-3'-deoxythymidine (bwa509u) to inhibit the replication of the retrovirus avian leukosis virus. inhibition was measured with two different assays: inhibition of a single round of virus replication and inhibition of virus spread through a cell culture. with both assays, we detected inhibition of virus growth, although inhibition of a single round of virus replication required a 40-fold higher drug concentration than did inhibition of virus spr ...19872441079
influence of maternal antibody on avian leukosis virus infection in white leghorn chickens harboring endogenous virus-21 (ev21).slow-feathering (sf) white leghorn dams harboring the endogenous viral gene ev21, which encodes for complete endogenous virus-21 (ev21), and rapid-feathering (rf) dams lacking ev21 were immunized with a live field strain of avian leukosis virus (alv) subgroup a. one group of sf dams and one group of rf dams were not immunized and were maintained to produce chicks lacking maternal alv antibody. when the sf dams were crossed with line 15b1 males, the resulting male progeny were sf, ev21-positive, ...19911659362
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 ...19921319049
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 ...19921322760
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 ...19921326313
follicular exclusion of retroviruses in the bursa of fabricius.to gain insight into the regulation of retroviral infection at the cellular level, we analyzed the distribution of retroviral antigen and nucleic acid in the bursa of fabricius of the parents and progeny of two highly inbred lines of chickens, one resistant and the other susceptible to infection. line 15i5 chickens and line 7(2), which are c/c and c/a, respectively, and 15i5 x 7(2) f1 chickens were infected with either rav-1 or rav-49 avian leukosis virus (alv). most bursal follicles of f1 chick ...19892543123
effect of avian leukosis virus infection on productivity of layers. 19921327184
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 ...19921328681
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 ...19921329706
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 ...1979225505
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 ...1979225563
immune response and resistance to rous sarcoma virus challenge of chickens immunized with cell-associated glycoproteins provided with a recombinant avian leukosis virus.the rous-associated virus 1 env gene, which encodes the envelope gp85 and gp37 glycoproteins, was isolated and inserted in place of the v-erbb oncogene into an avian erythroblastosis virus-based vector, carrying the neo resistance gene substituted for the v-erba oncogene, to generate the pnea recombinant vector. a helper-free virus stock of the pnea vector was produced on an avian transcomplementing cell line and used to infect primary chicken embryo fibroblasts (cefs) or quail qt6 cells. these ...19911654445
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 ...19921326106
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 ...19921326647
inhibition of proliferation of primary avian fibroblasts through expression of histone h5 depends on the degree of phosphorylation of the protein.to obtain stable and constitutive expression of histone h5 at levels comparable to those observed in normal chicken erythrocytes, an avian self-inactivating retroviral vector was used to transfer the h5 gene into cells which do not express this protein. the vector, pdah5, was obtained by removing the caat and tata boxes of the 3'ltr of the avian leukosis virus rav-2 and inserting the h5 sequence. infection of qt6 quail cells with the recombinant virus (dah5) led to the stable integration of the ...19911849905
increased ratio of targeted to random integration after transfection of chicken b cell lines.constructs of four different genetic loci were transfected into the avian leukosis virus-induced chicken b cell line dt40, which continues diversification of its rearranged light chain immunoglobulin gene by gene conversion. analysis of stable transfectants revealed an unexpectedly high frequency of targeted integration into the homologous gene loci of dt40. transcriptional activity of the target gene locus is not required, since a construct of the untranscribed ovalbumin gene also integrated pr ...19911913816
isolation of a variant endogenous avian leukosis virus: non-productive exogenous infection with endogenous viruses containing p27 and p27(0).ten replication-competent endogenous avian leukosis viruses (alvs) with subgroup e specificity were isolated from six commercial chicken lines of mixed breed. all the alvs isolated belonged to a variant class of endogenous viruses with a major group-specific antigen, p27, identical in size to that of exogenous viruses and different from the p27 degrees of endogenous viruses isolated from white leghorn chickens. it was possible to infect chickens exogenously with endogenous viruses (containing p2 ...19882832527
the v-ski oncogene encodes a truncated set of c-ski coding exons with limited sequence and structural relatedness to v-myc.the nucleotide sequence of a biologically active v-ski gene from a cloned proviral segment shows that ski is a 1,312-base sequence embedded in the p19 region of the avian leukosis virus gag gene. the v-ski sequence contains a single open translational reading frame that encodes a polypeptide with a molecular mass of 49,000 daltons. the predicted amino acid sequence includes nuclear localization motifs that have been identified in other nuclear oncoproteins. it also contains a proline-rich region ...19892674685
isolation and characterization of three distinct cdnas for the chicken c-ski gene.three types of c-ski cdnas have been isolated from two different chicken cdna libraries. sequence comparisons suggest that the cdnas derive from alternatively spliced mrnas. a short stretch of sequence homology that exists between c-ski and avian leukosis virus may have played a role in viral transduction.19892779576
ongoing diversification of the rearranged immunoglobulin light-chain gene in a bursal lymphoma cell line.the chicken immunoglobulin light-chain gene (igl) encodes only a single variable gene segment capable of recombination. to generate an immune repertoire, chickens diversify this unique rearranged vl gene segment during b-cell development in the bursa of fabricius. sequence analysis of igl cdnas suggests that both gene conversion events derived from vl segment pseudogene templates (psi vl) and non-template-derived single-base-pair substitutions contribute to this diversity. to facilitate the stud ...19902111450
preparation of a detailed restriction map of the avian leukosis virus mav-2(o).unintegrated mav-2(o) dna was isolated from infected chicken embryo fibroblasts and inserted into the lambda bacteriophage vector lambda gtwes lambda b. three x 10(6) bacteriophage plaques were screened, yielding a total of seven clones, six of which contained dna representing the complete mav-2(o) genome. viral dna was isolated from four of the clones and was used to transfect chicken embryo fibroblasts. all four clones produced virus as monitored by reverse transcriptase assay. when the four c ...19902157399
infrequent involvement of c-fos in avian leukosis virus-induced nephroblastoma.to determine whether c-fos is involved in avian leukosis virus-induced nephroblastoma, 28 tumors from chickens were analyzed for novel fos fragments. dna from 1 of 16 clonal outgrowths (in chicken 6561) contained novel fos-related ecori and kpni fragments which hybridized to both v-fos and viral probes. oncogenicity tests using filtered 6561 tumor cell homogenates did not reveal a tumor-inducing transduction of c-fos. we conclude that c-fos is only an occasional target for proviral insertions or ...19902161956
an avian transforming retrovirus isolated from a nephroblastoma that carries the fos gene as the oncogene.a new avian transforming retrovirus, nk24, was isolated from a chicken with a nephroblastoma. this transforming virus induced fibrosarcomas with osteogenic cell proliferation and nephroblastomas in vivo and transformed fibroblast cells in vitro. from extracts of nk24-transformed cells, anti-gag serum immunoprecipitated a 100-kilodalton nonglycosylated protein with no detectable protein kinase activity. an nk24 provirus present in infected quail cells was molecularly cloned and subjected to nucle ...19872824811
expression of retroviral genes in transgenic chickens.the development of transgenic technology in poultry has lagged behind that in mammals because of the unique reproductive system of birds. therefore, we chose to use wild-type and recombinant replication-competent avian leukosis viruses to determine whether these retroviruses could be artificially introduced into the germ line by injecting them near the blastoderm of fertile eggs just before incubation. we generated 23 proviral inserts that were stably inherited through two generations. twenty-on ...19902170639
interactions between endogenous virus loci ev6 and ev21. 1. immune response to exogenous avian leukosis virus infection.the effects of ev6, ev21, sex, and hatch, were studied with respect to avian leukosis virus (alv) viremia, cloacal shedding, and antibody response among rpl-40 virus-infected white leghorns that carried ev6 and ev21 in all combinations. among the four possible ev genotypes, chickens that carried only ev21 were the most immunologically tolerant to rpl-40 infection. incidence of rpl-40 viremia was lowest among hatchmates that lacked both ev genes. analysis of variance indicated significant interac ...19902172951
vectors and genes for improvement of animal strains.strain improvement of agriculturally important animals will require efficient techniques for gene delivery, the ability to regulate the expression of the newly introduced genes and, most important, the identification of genes whose appropriate expression could cause improvement of the animal. we have developed a series of avian retroviral vectors that can be used to introduce new genetic information into the germ line of chickens, for which transgenics cannot be created by direct microinjection ...19902213714
effects of chemically or virus-induced immunodepression on response of chickens to avian leukosis virus.the effects of chemically or virus-induced immunodepression on the infection profile (development of viremia and antibody) and shedding of avian leukosis virus (alv) were studied in progeny chickens of experimental or commercial breeder flocks. chickens were infected with alv subgroup a by contact at hatching and by oral inoculation at 4-5 weeks of age. in the first experiment, chickens were inoculated with a virulent strain of infectious bursal disease virus (ibdv) at 1 day or 6 weeks of age. i ...19852985037
major histocompatibility complex class ii (ia-like) antigens on chicken embryo fibroblasts: effect of transformation by rous sarcoma virus.in this study, three monomorphic monoclonal antibodies to chicken mhc class ii molecules (b-l) were tested for reactivity in normal and rsv-transformed embryo fibroblasts. the immunocytochemical staining, the cell-bound elisa assay, and the immunoprecipitation analysis showed that all three antibodies reacted with the b-l (ia-like) molecules on normal cells of different genotypes. conversely, the expression of these antigens was not detected in fibroblasts cultured from feather follicles of adul ...19892483835
augmentation of retrovirus-induced lymphoid leukosis by marek's disease herpesviruses in white leghorn chickens.our objective was to determine whether the cell-associated herpesvirus vaccines used in chickens to control marek's disease tumors can augment development of lymphoid leukosis (ll) induced by exogenous avian leukosis virus (alv). various single or mixed marek's disease vaccines were inoculated at day 1, and alv was injected at 1 to 10 days, with chickens of several experimental or commercial strains. development of ll was monitored at 16 to 48 weeks in various experiments. in several strains of ...19892536088
insertional activation of c-myc by reticuloendotheliosis virus in chicken b lymphoma: nonrandom distribution and orientation of the proviruses.chicken syncytial virus, a member of the reticuloendotheliosis virus family, can induce chicken b lymphomas indistinguishable from those caused by avian leukosis virus. previously, we have demonstrated that the chicken syncytial virus proviruses in these tumors are linked to the proto-oncogene c-myc. we have now determined the arrangement of chicken syncytial virus proviruses in 22 tumors. the results indicate that these proviruses, without exception, are integrated upstream from the second c-my ...19852987538
variation in susceptibility to avian sarcoma viruses and expression of endogenous avian leukosis virus antigens in specific pathogen-free chicken lines.five lines of chickens maintained as specific pathogen-free flocks in australia were characterized in relation to endogenous antigens and endogenous avian leukosis virus expression. embryos of line n were predominantly of c/e phenotype, uniformly positive for group-specific antigen and chick helper factor (gs+chf+) and 38% expressed endogenous virus at a very low titre. embryos of line m4 were uniformly of c/abe phenotype and were either gs+chf+ or gs-chf+. line w19 embryos segregated for suscep ...19852991436
generation of a helper cell line for packaging avian leukosis virus-based vectors.we constructed an avian leukosis virus-based packaging cell line, phf-g, containing rous-associated virus dna with several alterations to abolish rna packaging. one of them is a 52-base-pair deletion encompassing the putative encapsidation signal in the leader region. the 3' long terminal repeat was also removed and replaced by the polyadenylation sequence from the herpes simplex virus thymidine kinase gene. when phf-g cells were transfected by an avian leukosis virus-based vector, they produced ...19892536089
patterns of proviral insertion and deletion in avian leukosis virus-induced lymphomas.sixty-eight lymphomas induced by eight different avian leukosis viruses have been analyzed on southern blots for virus-induced mutations in the chicken c-myc gene. sixty-six of the lymphomas exhibited a proviral insertion in c-myc, whereas one exhibited a new transduction of c-myc. sixty-four of the proviral insertions were in the same transcriptional orientation as c-myc. two were in the opposite transcriptional orientation. all of the insertions were upstream of the protein-coding sequences of ...19863001351
rav-1 insertional mutagenesis: disruption of the c-myb locus and development of avian b-cell lymphomas.infection of young chickens with rav-1, a subgroup a isolate of avian leukosis virus, results in the development of lymphoid leukosis, a b-cell lymphoma characterized by provirus insertion into the c-myc locus. we report here that when 12- to 13-day-old embryos rather than 1-day-old chickens were infected with rav-1, a novel b-cell lymphoma developed in which proviral insertions had activated expression of the c-myb gene. these tumors expressed elevated levels of a 4.5-kilobase myb-containing mr ...19892538646
disease tropism of c-erbb: effects of carboxyl-terminal tyrosine and internal mutations on tissue-specific transformation.avian leukosis virus induces erythroleukemia in chickens by proviral insertional mutation of the protooncogene c-erbb. the product of the insertionally activated c-erbb locus lacks the extracellular ligand-binding domain and is strictly leukemogenic. it has previously been demonstrated that the disease spectrum associated with aberrant c-erbb expression can be expanded by structural perturbation of the cytoplasmic domain of this protein. in this report, we use mutagenesis and retroviral vectors ...19892550929
fh3, a v-myc avian retrovirus with limited transforming ability.we have isolated a new acute avian transforming virus which contains the oncogene myc. this virus, designated fh3, was isolated after injection of a 10-day-old chick embryo with avian leukosis virus. while fh3 shares many properties with other v-myc-containing avian retroviruses, it also has several unique properties. the primary target for transformation in vitro is chicken macrophages; infection of chicken fibroblasts does not lead to complete morphological transformation. fh3 also exhibits a ...19892555545
avian leukosis virus-induced osteopetrosis is associated with the persistent synthesis of viral dna.dnas from 19 cases of avian leukosis virus-induced osteopetrosis have been analyzed for viral sequences. among these were instances of rapid, intermediate, and slow onset osteopetrosis. the dnas from osteopetrotic bone contained no evidence for osteopetrosis being caused by proviral insertions into or viral transductions of a host protooncogene. instead, dnas from osteopetrotic bone displayed evidence for osteopetrosis being associated with the persistent synthesis of viral dna. each of the 19 d ...19852579505
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 ...19921331625
rag-2 expression is not essential for chicken immunoglobulin gene conversion.chicken b cells diversify their immunoglobulin genes by gene conversion in the bursa of fabricius. the avian leukosis virus-induced b-cell line dt40 continues to diversify its immunoglobulin light chain locus by gene conversion during in vitro passage. since a variable(diversity)joining recombination-activating gene, rag-2, is specifically expressed in chicken b cells undergoing immunoglobulin gene conversion, it has been suggested that rag-2 may be involved in the immunoglobulin gene conversion ...19921570327
a novel subgroup of exogenous avian leukosis virus in chickens.an avian leukosis virus with a wide host range belonging to a new subgroup for chickens was isolated from meat-type chicken lines. the virus, of which hprs-103 strain is the prototype, was of low oncogenicity in chickens but appeared to behave like an exogenous leukosis virus. neutralizing antibodies to the virus were found in three of five meat-type chicken lines, but not in seven layer lines. the virus and its rous sarcoma virus pseudotype did not replicate in, or transform, mammalian cells.19911849967
avian leukosis virus (alv) infection, shedding, and tumors in maternal alv antibody-positive and -negative chickens exposed to virus at hatching.chickens highly susceptible to avian leukosis virus (alv) infection and tumors, with and without alv subgroup a maternal antibody (mab), were infected with a field strain of alv subgroup a at hatching. viremia, antibody development, cloacal and albumen shedding, and tumors in chickens with mab (mab+) were compared with those in chickens lacking mab (mab-). at 18 weeks of age, the incidence of viremia was significantly lower in mab+ chickens than in mab- chickens; further, mab significantly reduc ...19882838017
immune response of chickens inoculated with a recombinant avian leukosis virus.specific-pathogen-free embryos (18-day incubation) and hatched chicks were inoculated with a recombinant avian leukosis virus (alv) produced by recombinant dna techniques. enzyme-linked immunosorbent assays were used to measure the production of viral-protein-specific antibody and the viral protein, p27, in the serum at 2, 5, 8, 14, and 20 weeks of age. of the inoculated chickens surviving to 20 weeks, 64% produced viral-protein-specific antibodies and 42% transiently produced the viral protein, ...19882838018
selective integration of avian leukosis virus in different hematopoietic tissues.hematopoietic tissues obtained from avian leukosis virus (alv)-infected hyline sc chickens were analyzed for the presence of integrated viral dna sequences. cells were prepared from bone marrow, bursa, spleen, thymus, and peripheral blood. following the removal of erythrocytes, cellular dnas from each of these tissues were examined by southern analysis. during the first few weeks of infection, dna from the bone marrow contained as many as 0.5 copies of viral dna per haploid genome. cells from th ...19863024400
restrictions that influence avian leukosis virus-induced lymphoid leukosis. 19863024914
features of the chicken c-myc gene that influence the structure of c-myc rna in normal cells and bursal lymphomas.the chicken c-myc gene is the target for proviral insertion mutations in bursal lymphomas and has been transduced to generate several viral oncogenes, but the boundaries of its exons have not been securely established. to define the landmarks of the chicken c-myc gene necessary to produce its mrna, we used an rnase protection assay and a cdna clone to analyze the c-myc mrnas from normal chicken embryos and from two bursal lymphomas: ll6, which contains an avian leukosis virus provirus downstream ...19862431293
reduced expression of mhc class i antigens in chicken fibroblasts transformed by rous sarcoma virus.monoclonal monomorphic as well as polyclonal antibodies against h-b class i (b-f) antigen were used to evaluate the expression of these molecules on normal and rsv-transformed chick embryo fibroblasts. the results indicate that chicken fibroblasts transformed in vitro by the schmidt-ruppin strain rous sarcoma virus of subgroup b (sr-rsv-b) present reduced h-b class i antigen expression as compared to uninfected cells of the same inbred strain. this quantitative reduction was observed at the cell ...19872826262
development of avian sarcoma and leukosis virus-based vector-packaging cell lines.we have constructed an avian leukosis virus derivative with a 5' deletion extending from within the trna primer binding site to a saci site in the leader region. our aim was to remove cis-acting replicative and/or encapsidation sequences and to use this derivative, rav-1 psi-, to develop vector-packaging cell lines. we show that rav-1 psi- can be stably expressed in the quail cell line qt6 and chicken embryo fibroblasts and that it is completely replication deficient in both cell types. moreover ...19882828649
formation of a transformed follicle is necessary but not sufficient for development of an avian leukosis virus-induced lymphoma.avian leukosis virus (alv) infection of susceptible chickens induces bursal lymphomas after a latent period of several months. the clonal development of these b-cell tumors is believed to be a multistep process. histopathological changes, referred to as transformed follicles, occur within the target organ soon after virus infection and may represent a proximal stage of lymphomagenesis. to establish further the significance of this lesion and its relationship to the subsequent development of lymp ...19852982144
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