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Infection and Immunity Feb 1979Inoculation 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...
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.
Topics: Alpharetrovirus; Animals; Antibodies, Viral; Avian Leukosis; Avian Sarcoma Viruses; Bursa of Fabricius; Chickens; Macrophages; Sarcoma, Avian; Spleen
PubMed: 217827
DOI: 10.1128/iai.23.2.294-297.1979 -
Proceedings of the National Academy of... Apr 1994The oncogene hypothesis postulates that mutated cellular genes, termed proto-onc genes, function as cancer genes because they are related to retroviral onc genes....
The oncogene hypothesis postulates that mutated cellular genes, termed proto-onc genes, function as cancer genes because they are related to retroviral onc genes. However, in contrast to retroviral onc genes, mutated proto-onc genes from cancers are not sufficient for carcinogenesis. Therefore, it has been proposed that mutated proto-onc genes depend on other proto-onc genes for carcinogenesis. Since the oncogene of the avian leukemia virus E26 includes coding regions derived from two cellular proto-onc genes, proto-myb and proto-ets, this hybrid gene has been proposed to be a model for two-gene-carcinogenesis. Here we set out to test this proposal. For this purpose myb and ets deletion mutants of cloned E26 provirus were prepared, and the corresponding viruses, produced by transfected primary chicken embryo cells, were tested for leukemogenicity in newborn chickens. It was found that an ets deletion mutant was just as leukemogenic as the wild-type virus and that a myb deletion mutant lacked leukemogenicity completely. To eliminate the possibility that our E26 myb deletion mutant failed to be leukemogenic because it failed to replicate, the virus was titered by a quantitative polymerase chain reaction (PCR) method. By this method, E26 from the plasma of infected chickens was first allowed to reverse-transcribe viral RNA to cDNA in vitro, and then the cDNA concentration was determined from the lowest dilution that gave a positive signal after amplification of E26 cDNA by the PCR method. Virus titers of about 10(5) per ml were found for wild type and for myb and ets deletion mutants of E26. It is concluded that the ets region is not essential for carcinogenesis, and E26 derives transforming function from overexpression of its proto-myb coding region via the retroviral promoter. Thus, E26 is a single-hit carcinogen and, like all other oncogenic retroviruses, is not a model for two-gene-carcinogenesis. Viral ets probably reflects a genetic accident that transduced sequences of proto-ets together with proto-myb in generating E26.
Topics: Alpharetrovirus; Animals; Chickens; Leukemia, Experimental; Oncogene Proteins v-myb; Oncogenes; Retroviridae Proteins, Oncogenic; Sequence Deletion; Virus Replication
PubMed: 8171032
DOI: 10.1073/pnas.91.9.4039 -
Journal of Virology Apr 1999The receptor for the subgroup A avian sarcoma and leukosis viruses [ASLV(A)] is the cellular glycoprotein Tva. A soluble form of Tva, sTva, was produced and purified...
The receptor for the subgroup A avian sarcoma and leukosis viruses [ASLV(A)] is the cellular glycoprotein Tva. A soluble form of Tva, sTva, was produced and purified with a baculovirus expression system. Using this system, 7 to 10 mg of purified sTva per liter of cultured Sf9 cells was obtained. Characterization of the carbohydrate modification of sTva revealed that the three N glycosylation sites in sTva were differentially utilized; however, the O glycosylation common to Tva produced in mammalian and avian cells was not observed. Purified sTva demonstrates significant biological activity, specifically blocking infection of avian cells by ASLV(A) with a 90% inhibitory concentration of approximately 25 pM. A quantitative enzyme-linked immunosorbent assay, developed to assess the binding of sTva to ASLV envelope glycoprotein, demonstrates that sTva has a high affinity for EnvA, with an apparent dissociation constant of approximately 0.3 nM. Once they are bound, a very stable complex is formed between EnvA and sTva, with an estimated complex half-life of 6 h. The soluble receptor protein described here represents a valuable tool for analysis of the receptor-envelope glycoprotein interaction and for structural analysis of Tva.
Topics: Alpharetrovirus; Amino Acid Sequence; Animals; Avian Proteins; Baculoviridae; Cell Line; Molecular Sequence Data; Receptors, Virus
PubMed: 10074155
DOI: 10.1128/JVI.73.4.3054-3061.1999 -
Pathology and Immunopathology Research 1987
Review
Topics: Alpharetrovirus; Animals; Avian Leukosis Virus; Base Sequence; Birds; Molecular Sequence Data; Mutation; Oncogene Proteins, Viral; Oncogenes; Oncogenic Viruses
PubMed: 2850548
DOI: 10.1159/000157065 -
Advances in Virus Research 1985
Review
Topics: Alpharetrovirus; Animals; Avian Leukosis; Base Sequence; Chickens; Cloning, Molecular; Gene Expression Regulation; Genes, Viral; RNA, Viral; Repetitive Sequences, Nucleic Acid; Transcription, Genetic; Virus Replication
PubMed: 3008523
DOI: 10.1016/s0065-3527(08)60451-0 -
Tanpakushitsu Kakusan Koso. Protein,... Sep 1986
Review
Topics: Alpharetrovirus; Amino Acid Sequence; Avian Leukosis Virus; Carcinoma, Squamous Cell; Cell Transformation, Neoplastic; ErbB Receptors; Gene Frequency; Humans; Oncogenes; RNA, Messenger
PubMed: 3024233
DOI: No ID Found -
The Journal of Biological Chemistry May 2011Enveloped viruses must fuse the viral and cellular membranes to enter the cell. Understanding how viral fusion proteins mediate entry will provide valuable information...
Simple, automated, high resolution mass spectrometry method to determine the disulfide bond and glycosylation patterns of a complex protein: subgroup A avian sarcoma and leukosis virus envelope glycoprotein.
Enveloped viruses must fuse the viral and cellular membranes to enter the cell. Understanding how viral fusion proteins mediate entry will provide valuable information for antiviral intervention to combat associated disease. The avian sarcoma and leukosis virus envelope glycoproteins, trimers composed of surface (SU) and transmembrane heterodimers, break the fusion process into several steps. First, interactions between SU and a cell surface receptor at neutral pH trigger an initial conformational change in the viral glycoprotein trimer followed by exposure to low pH enabling additional conformational changes to complete the fusion of the viral and cellular membranes. Here, we describe the structural characterization of the extracellular region of the subgroup A avian sarcoma and leukosis viruses envelope glycoproteins, SUATM129 produced in chicken DF-1 cells. We developed a simple, automated method for acquiring high resolution mass spectrometry data using electron capture dissociation conditions that preferentially cleave the disulfide bond more readily than the peptide backbone amide bonds that enabled the identification of disulfide-linked peptides. Seven of nine disulfide bonds were definitively assigned; the remaining two bonds were assigned to an adjacent pair of cysteine residues. The first cysteine of surface and the last cysteine of the transmembrane form a disulfide bond linking the heterodimer. The surface glycoprotein contains a free cysteine at residue 38 previously reported to be critical for virus entry. Eleven of 13 possible SUATM129 N-linked glycosylation sites were modified with carbohydrate. This study demonstrates the utility of this simple yet powerful method for assigning disulfide bonds in a complex glycoprotein.
Topics: Alpharetrovirus; Animals; Cell Line; Chickens; Glycoproteins; Glycosylation; Mass Spectrometry; Recombinant Proteins; Viral Envelope Proteins
PubMed: 21454567
DOI: 10.1074/jbc.M111.229377 -
Advances in Virus Research 1972
Review
Topics: Alpharetrovirus; Animals; Cell Line; Cell Transformation, Neoplastic; Chick Embryo; Chickens; Cricetinae; Dogs; Ducks; Guinea Pigs; Haplorhini; Humans; Macaca; Mice; Mice, Inbred C57BL; Microscopy, Electron; Neoplasms; Papio; Parainfluenza Virus 1, Human; Rabbits; Radiation Effects; Rats; Time Factors; Ultraviolet Rays
PubMed: 4348511
DOI: No ID Found -
BMC Developmental Biology Oct 2010The use of Specific Pathogen Free (SPF) eggs in combination with RCAS retrovirus, a member of the Avian Sarcoma-Leukosis Virus (ASLV) family, is of standard practice to...
BACKGROUND
The use of Specific Pathogen Free (SPF) eggs in combination with RCAS retrovirus, a member of the Avian Sarcoma-Leukosis Virus (ASLV) family, is of standard practice to study gene function and development. SPF eggs are certified free of infection by specific pathogen viruses of either exogenous or endogenous origin, including those belonging to the ASLV family. Based on this, SPF embryos are considered to be free of ASLV viral protein expression, and consequently in developmental research studies RCAS infected cells are routinely identified by immunohistochemistry against the ASLV viral proteins p19 and p27. Contrary to this generally accepted notion, observations in our laboratory suggested that certified SPF chicken embryos may endogenously express ASLV viral proteins p19 and p27. Since these observations may have significant implications for the developmental research field we further investigated this possibility.
RESULTS
We demonstrate that certified SPF chicken embryos have transcriptionally active endogenous ASLV loci (ev loci) capable of expressing ASLV viral proteins, such as p19 and p27, even when those loci are not capable of producing viral particles. We also show that the extent of viral protein expression in embryonic tissues varies not only among flocks but also between embryos of the same flock. In addition, our genetic screening revealed significant heterogeneity in ev loci composition even among embryos of the same flock.
CONCLUSIONS
These observations have critical implications for the developmental biology research field, since they strongly suggest that the current standard methodology used in experimental studies using the chick embryo and RCAS vectors may lead to inaccurate interpretation of results. Retrospectively, our observations suggest that studies in which infected cells have been identified simply by pan-ASLV viral protein expression may need to be considered with caution. For future studies, they point to a need for careful selection and screening of the chick SPF lines to be used in combination with RCAS constructs, as well as the methodology utilized for qualitative analysis of experimental results. A series of practical guidelines to ensure research quality animals and accuracy of the interpretation of results is recommended and discussed.
Topics: Alpharetrovirus; Animals; Chick Embryo; Developmental Biology; Genetic Vectors; Guidelines as Topic; Specific Pathogen-Free Organisms; Viral Proteins
PubMed: 20955591
DOI: 10.1186/1471-213X-10-106 -
The Journal of General Virology Nov 1971
Topics: Alleles; Alpharetrovirus; Animals; Avian Sarcoma Viruses; Chick Embryo; Crosses, Genetic; Crossing Over, Genetic; Gene Frequency; Genetic Linkage; Genetics, Microbial; Genotype; Phenotype; Recombination, Genetic
PubMed: 4333713
DOI: 10.1099/0022-1317-13-2-253