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Biphasic DNA synthesis in spumaviruses.
Olivier Delelis1, Ali Saïb, Pierre Sonigo
1Département des Maladies Infectieuses, Institut Cochin, INSERM U 567 et CNRS UMR 8104, 22 rue Méchain, 75014 Paris, France.
Journal of Virology
|June 28, 2003
Summary
Spumaviruses exhibit early and late reverse transcription, a process crucial for their DNA synthesis and replication. This dual-phase reverse transcription, inhibited by 3'-azido-3'-deoxythymidine, is key to spumavirus propagation.
Area of Science:
- Virology
- Molecular Biology
- Retroviral Research
Background:
- Spumaviruses are complex retroviruses with a replication cycle sharing similarities with hepadnaviruses, notably a late reverse transcription phase.
- The potential for an early reverse transcription phase, common in other retroviruses, remained uninvestigated in spumaviruses.
Purpose of the Study:
- To investigate the kinetics of viral DNA synthesis during spumavirus infection.
- To determine the presence and timing of early reverse transcription in spumaviruses.
Main Methods:
- Real-time quantitative PCR was employed to monitor viral DNA synthesis kinetics.
- The effect of the reverse transcriptase inhibitor 3 -azido-3 -deoxythymidine was assessed on viral DNA synthesis phases.
Main Results:
- Two distinct phases of viral DNA synthesis were identified: an early phase up to 3 hours post-infection and a second phase peaking at 10 hours post-infection.
- Both synthesis phases were significantly inhibited by 3 -azido-3 -deoxythymidine, confirming reverse transcriptase activity.
- Circular viral DNA forms with two long terminal repeats were predominantly found in the nucleus, but also detected in the cytoplasm and extracellular virions.
Conclusions:
- Spumaviruses undergo both early and late reverse transcription, contributing to viral DNA synthesis.
- The presence of circular DNA in cytoplasm and virions, along with genome packaging, suggests a mechanism for efficient spumavirus replication.