Localization of simian adenovirus 7 (SA 7) transcription and replication in lytic infection. An ultracytochemical and autoradiographical study.
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We have studied SA7 (simian adenovirus 7) lytic infection at the ultrastruct level. The use of cytochemical techniques which specifically stain DNA or preferentially stain ribonucleoproteins permitted the analysis of the structure of the virus-induced nuclear inclusions, and revealed presumed virus DNA before the appearance of other nuclear alterations. Correlation of these findings with high resolution autoradiography enabled the functions of virus DNA replication and transcription to be ascribed to a defined nuclear inclusion. We demonstrate that the nucleolus remains distinct from the inclusion body, contrary to the situation in other adenovirus-infected cells. The functional role of host cell chromatin and of the nucleolus are discussed. (+info)
The distribution of guanine-cytosine pairs in adenovirus DNAs.
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The distribution of guanine-cytosine (GC) pairs in the DNA of the highly oncogenic simian adenovirus type 7 (SA7) and the non-oncogenic human adenovirus type 6 (Ad6) has been studied by thermal denaturation and CsC1 density-gradient centrifugation. The differential of the DNA thermal denaturation curves shows the presence of pronounced peaks which indicates uneven distribution of GC pairs along the DNA chains and the presence of regions with GC content from 30 to 74% in SA7 DNA and from 40 to 68% in Ad6 DNA. The DNA restriction fragments obtained by treatment with EcoRI, BamHI, SalI, BglII and HindIII were subjected to CsC1 density-gradient centrifugation. GC content of the fragments ranged from 45 to 70% for SA7 DNA and from 43 to 61% for Ad6 DNA. The GC content of the extreme left-hand fragments, where the transforming gene(s) is located, was higher than the average for SA7 DNA and lower than the average for Ad6 DNA. The most GC-rich regions were localized in the centre of the genome. The GC content of the right-hand part of both viral genomes was lower than the average. (+info)
Human and simian adenoviruses: phylogenetic inferences from analysis of VA RNA genes.
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Adenovirus VA RNA genes have primary sequence constraints due to internal promoter regions and a high degree of secondary structure in the RNA product. To determine the relationships between human and simian adenoviruses, the VA RNA genes of several primate adenoviruses were characterized and compared to those sequences already published. Human adenoviruses of subgenera A, B:2, and F have only one VA RNA gene, whereas human adenoviruses of subgenera B:1, C, D, and E have two. The genomes of 12 monkey adenoviruses were found to have only one VA RNA gene, whereas the genomes of six representative chimpanzee adenoviruses were each found to have two VA RNA genes. Phylogenetic analysis of representative VA RNA gene sequences individually, irrespective of their strain of origin or partnering VA RNA gene, gave the following inferences. (1) The single VA RNA genes of human adenovirus subgenera A and F are most closely related to those of monkey adenoviruses. (2) The VA RNAI genes of human adenoviruses in subgenera B:1, D, and E, and also the single VA RNA genes of subgenus B:2 probably diverged from a common ancestral VA RNA gene. (3) This ancestral gene most likely reduplicated to give the precursor of all VA RNAII genes, the evidence for which has been almost totally lost in subgenus B:2 adenoviruses. (4) The two VA RNA genes of human subgenus C adenoviruses are relatively distant from each other phylogenetically. Since the Ad2 and Ad5 VA RNAI genes have a higher identity to the single VA RNA gene of SAV13 (SV36) than to those of any of the other human adenoviruses, these genes may have entered the human subgenus C adenovirus genome by substitution involving recombination with a simian adenovirus. The results of this study suggest that a renewed appraisal of VA RNA function in adenoviruses other than Ad2 and Ad5 may be necessary. (+info)
Binding-incompetent adenovirus facilitates molecular conjugate-mediated gene transfer by the receptor-mediated endocytosis pathway.
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Molecular conjugate vectors may be constructed that accomplish high efficiency gene transfer by the receptor-mediated endocytosis pathway. In order to mediate escape from lysosomal degradation, we have incorporated adenoviruses into the functional design of the conjugate. In doing so, however, we have introduced an additional ligand, which can bind to receptors on the cell surface, undermining the potential for cell specific targeting. To overcome this, we have treated the adenovirus with a monoclonal anti-fiber antibody, which renders the virus incapable of binding to its receptor. The result is a multi-functional molecular conjugate vector, which has preserved its binding specificity while at the same time being capable of preventing lysosomal degradation of endosome-internalized conjugate-DNA complexes. This finding indicates that adenoviral binding is not a prerequisite for adenoviral-mediated endosome disruption. (+info)