Biphasic DNA synthesis in spumaviruses.
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.
Delelis
Olivier
O
Département des Maladies Infectieuses, Institut Cochin, INSERM U 567 et CNRS UMR 8104, 22 rue Méchain, 75014 Paris, France.
Saïb
Ali
A
Sonigo
Pierre
P
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
D004279:DNA, Viral; D018894:Reverse Transcriptase Inhibitors; D015215:Zidovudine