title: Biphasic DNA synthesis in spumaviruses.
abstract: Spumaviruses are complex retroviruses whose replication cycle resembles that of hepadnaviruses, especially by a late-occurring reverse transcription step. The possible existence of an early reverse transcription as observed in other retroviruses was not documented. Using real-time quantitative PCR, we addressed directly the kinetics of DNA synthesis during spumavirus infection. An early phase of viral DNA synthesis developed until 3 h postinfection, followed by a second phase, culminating 10 h postinfection. Both phases were abolished by the reverse transcriptase inhibitor 3'-azido-3'-deoxythymidine. Similar to other retroviruses, circular forms of viral DNA harboring two long terminal repeats were mainly found in the nucleus of infected cells. Interestingly, a fraction of these circular forms were detected in the cytoplasm and in extracellular virions, a feature shared with hepadnaviruses. Combined with packaging of both viral DNA and RNA genomes in virions, early and late reverse transcription might allow spumavirus to maximize its genome replication.
authors.affiliation: Département des Maladies Infectieuses, Institut Cochin, INSERM U 567 et CNRS UMR 8104, 22 rue Méchain, 75014 Paris, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Delelis
authors.forename: Ali
authors.initials: A
authors.lastname: Saïb
authors.forename: Pierre
authors.initials: P
authors.lastname: Sonigo
mesh_terms: D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D004261:DNA Replication; D004279:DNA, Viral / Q000096:biosynthesis*; D006801:Humans; D007700:Kinetics; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology; D016092:Spumavirus / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D014158:Transcription, Genetic; D014779:Virus Replication; D015215:Zidovudine / Q000494:pharmacology
chemical_list: D004279:DNA, Viral; D018894:Reverse Transcriptase Inhibitors; D015215:Zidovudine