DNA-binding proteins of chick embryo lethal orphan virus: lack of complementation between early proteins of avian and human adenoviruses.
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Chick cells infected by chick embryo lethal orphan (CELO) virus (fowl adenovirus type 1) contained four prominent virus-specific, structurally related DNA-binding proteins with mol. wt. of 74K, 64K, 56K, 52K, and two minor forms. The CELO virus DNA-binding proteins were phosphorylated, delayed-early nuclear proteins. CELO virus early proteins were expressed in BHK cells, but did not complement human adenovirus type 5 mutants with lesions E1A, E2A or E2B. Moreover, CELO virus DNA-binding proteins were not produced in 293 cells, which express human adenovirus E1 genes. These results suggest that activation of transcription by adenovirus E1A genes involves specific interactions between the E1A gene products and viral early promoters. (+info)
Structural organization and polypeptide composition of the avian adenovirus core.
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CELO virus (fowl adenovirus 1) contained three core polypeptides of molecular weights 20,000, 12,000, and 9,500. The core was similar to that of human adenoviruses, with some evidence of compact subcore domains. Micrococcal nuclease digestion of CELO virus cores produced a smear of DNA fragments of gradually decreasing size, with no nucleosome subunit or repeat pattern. Moreover, when digested cores were analyzed without protease treatment, there was again no evidence of a nucleosome substructure; neither DNA fragments nor core proteins entered a 4% polyacrylamide gel. The organization of the core is thus quite unlike that of chromatin. Restriction endonuclease analysis of the DNA from digested cores showed that the right end was on the outside of the core. We suggest that adenovirus DNA is condensed into the core by cross-linking and neutralization by the core proteins, beginning with the packaging sequence at the center of the core and ending with the right end of the DNA on the outside. (+info)
Studies on egg drop syndrome (EDS) and chick embryo lethal orphan (CELO) avian adenovirus DNAs by restriction endonucleases.
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Restriction endonucleases EcoRI, BamHI, HindIII, BglI, BglII, HpaI and PstI recognized 48 cleavage sites in EDS adenovirus strain B8/78 DNA, whereas CELO virus DNA was cut into 61 fragments by the same enzymes. No similarity could be detected in the restriction patterns obtained from the two avian adenoviruses. The calculated mol. wt. of B8/78 DNA was 22.6 X 10(6) [about 34.2 kilobases (kb)] and that of CELO virus DNA was 28.9 X 10(6) (about 43.7 kb). The fragments generated from B8/78 DNA by EcoRI and BamHI were physically mapped. (+info)
Sequence homology between avian and human adenoviruses.
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Studies of hybridization between fowl adenovirus type 1 (chicken embryo lethal orphan virus) DNA and human adenovirus type 2 DNA revealed two short but distinct regions which cross-hybridized under stringent conditions. One of the homologous regions was located between map positions 18.1 and 19.3 and did not correspond to any gene recognized so far. The second region mapped in the hexon gene between position 57 and 58. (+info)
A comparison of the terminal protein and hexon polypeptides of avian and human adenoviruses.
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It was found that the virion terminal protein of chick embryo lethal orphan (CELO) virus had a molecular weight of 46,000, and the hexon a molecular weight of 100,000. 125I-labelled tryptic and chymotryptic peptide maps of the hexons and terminal proteins from CELO virus and human adenovirus type 5 (Ad5) differed. However, limited proteolysis of CELO virus and Ad5 terminal proteins by protease V8 showed similarities which were not detected in the case of the two hexons. (+info)
Genomic mapping and sequence analysis of the fowl adenovirus serotype 10 hexon gene.
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The gene for the major capsid protein (hexon) of fowl adenovirus serotype 10 (FAV-10) has been identified by the use of the expression vector pGEX and rabbit polyclonal antisera raised against FAV-10. The nucleotide sequence of the entire hexon gene has been determined. Sequence analysis revealed an open reading frame of 2808 bp coding for a putative polypeptide 936 amino acids long with a molecular mass of 105.5 kDa. The translation initiation codon has a local sequence which conforms with the optimal translation start sequence of CC(A/G)CCATGG. The location of the hexon gene in the FAV genome was from 46.85 to 52.81 map units, which is to the left of the hexon gene in the genomes of both bovine and human adenovirus (52.4 to 60.5 map units.). A splice acceptor site was identified 12 bp upstream of the initiation codon by using mRNA and PCR. It had the sequence TAGG which conforms to the consensus sequence of (C/T)AGG. Comparison of the amino acid sequence of the FAV-10 hexon with those of the bovine, human and murine hexon gene products revealed highest levels of identity occurring in the regions corresponding to the pedestals which form the base region of the hexon, and the lowest levels of identity in the regions corresponding to the loops which are exposed to the external environment. (+info)
Chicken adenovirus (CELO virus) particles augment receptor-mediated DNA delivery to mammalian cells and yield exceptional levels of stable transformants.
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Delivery of genes via receptor-mediated endocytosis is severely limited by the poor exit of endocytosed DNA from the endosome. A large enhancement in delivery efficiency has been obtained by including human adenovirus particles in the delivery system. This enhancement is probably a function of the natural adenovirus entry mechanism, which must include passage through or disruption of the endosomal membrane. In an effort to identify safer virus particles useful in this application, we have tested the chicken adenovirus CELO virus for its ability to augment receptor-mediated gene delivery. We report here that CELO virus possesses pH-dependent, liposome disruption activity similar to that of human adenovirus type 5. Furthermore, the chicken adenovirus can be used to augment receptor-mediated gene delivery to levels comparable to those found for the human adenovirus when it is physically linked to polylysine ligand-condensed DNA particles. The chicken adenovirus has the advantage of being produced inexpensively in embryonated eggs, and the virus is naturally replication defective in mammalian cells, even in the presence of wild-type human adenovirus. (+info)
Pathogenesis of type II avian adenovirus infection in turkeys: in vivo immune cell tropism and tissue distribution of the virus.
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Hemorrhagic enteritis virus (HEV), a type II avian adenovirus, causes intestinal hemorrhages and immunosuppression in turkeys. In this study, we exposed turkeys to virulent HEV and examined fractionated spleen cells for the presence of viral DNA by in situ hybridization and amplification of DNA extracted from virus-infected cells by PCR. HEV replication was detected only in the immunoglobulin M-bearing B lymphocytes and macrophage-like cells but not in the CD4+ or CD8+ T lymphocytes. The inability to infect T cells distinguishes type II avian adenoviruses from lymphotropic mammalian adenoviruses which infect and replicate in T cells. Furthermore, these data suggested that HEV-induced immunosuppression in turkeys may be due to the effect of the virus on B lymphocytes and macrophages. We also examined tissue tropism of HEV by in situ hybridization conducted on sections of lymphoid and nonlymphoid tissues. Large numbers of HEV-positive cells were detected in spleen and cecal tonsils. Diminutive viral activity was present in the intestines, the principal site of HEV-induced pathology. Thus, intestinal pathology was not associated with local cytopathic viral replication. This result and our previous observation that cyclosporin A abrogated intestinal hemorrhaging in HEV-infected turkeys strongly suggested that intestinal lesion induced by this virus may be immune system mediated. (+info)