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Protease-dependent uncoating of a complex retrovirus
Jacqueline Lehmann-Che1, Marie-Lou Giron, Olivier Delelis
1CNRS UMR 7151-Université Paris 7, Hôpital Saint-Louis, 75010 Paris, France.
Journal of Virology
|July 5, 2005
Summary
Early retrovirus replication remains unclear. Foamy retroviruses show viral protease-dependent Gag cleavage is essential for nuclear import and productive infection, an unprecedented finding.
Area of Science:
- Virology
- Molecular Biology
- Cell Biology
Background:
- Retrovirus replication involves complex early stages, including uncoating, which are poorly understood.
- Foamy retroviruses serve as a model to investigate these early events.
Purpose of the Study:
- To elucidate the role of viral protease activity in early retroviral replication using foamy retroviruses.
- To investigate the necessity of Gag polyprotein processing for viral genome nuclear import and infectivity.
Main Methods:
- Utilized protease-defective and Gag cleavage site mutant foamy retroviruses.
- Tracked viral particle trafficking using microscopy after cell entry.
- Analyzed viral protein processing and genome localization post-infection.
Main Results:
- Protease-defective and Gag cleavage site mutant viruses efficiently budded and entered cells but were noninfectious.
- Wild-type viruses showed nuclear import of Gag and genome by 8 hours post-infection.
- Mutant viruses accumulated at the microtubule-organizing center (MTOC), with Gag cleavage products absent.
Conclusions:
- Viral protease-dependent cleavage of Gag is crucial for foamy retrovirus uncoating and nuclear import.
- This Gag cleavage is essential for productive infection, representing a novel step in the retroviral life cycle.