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Characterization of the Rep78/adeno-associated virus complex
K M Prasad1, C Zhou, J P Trempe
1Department of Biochemistry and Molecular Biology, Medical College of Ohio, Toledo 43699, USA.
Virology
|March 3, 1997
Summary
Adeno-associated virus (AAV) Rep78 protein covalently links to viral DNA, specifically at the 5' thymidine. This Rep78-DNA linkage is crucial for AAV replication and gene therapy vector transduction.
Area of Science:
- Molecular virology
- Gene therapy vectors
Background:
- Adeno-associated virus (AAV) replication proteins Rep78 and Rep68 are essential for its life cycle.
- Previous studies indicated a covalent association between Rep78 and single-stranded (ss) AAV DNA in vivo.
Purpose of the Study:
- To further characterize the covalent linkage between the Rep78 protein and AAV DNA.
- To investigate the role and persistence of this linkage during AAV infection and transduction.
Main Methods:
- Exonuclease and primer extension analyses to identify the linkage site.
- Pulse-chase experiments with radiolabeled methionine to track Rep protein association.
- Quantitative immunoprecipitation and cell fractionation to assess linkage stability.
Main Results:
- Rep78 protein is covalently linked to a 5' terminal thymidine in the majority of isolated ssAAV DNA.
- Rep protein remains associated with the virus particle for up to 8 hours post-labeling.
- Approximately 30% of ssDNA remains associated with Rep protein after cell fractionation.
- Viral DNA remains attached to Rep after nuclear entry, but the linkage is transient.
Conclusions:
- The covalent Rep78-AAV DNA linkage is a significant feature of wild-type AAV infections.
- This linkage likely plays a key role in both AAV replication and the efficacy of AAV-based gene therapy vectors.