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PKA/PrKX activity is a modulator of AAV/adenovirus interaction
Giovanni Di Pasquale1, John A Chiorini
1Gene Therapy and Therapeutics Branch, NIDCR, NIH 10/1N113, 10 Center Drive MSC 1190, Bethesda, MD 20892-1190, USA.
Abstract:
Interference between viruses occurs when infection by one virus results in the inhibition of replication of another virus. Adeno-associated virus (AAV2) is a human parvovirus with the unique characteristics of a dependence upon a helper virus for a productive infection and the ability to interfere with the replication of the helper virus. Previously, we demonstrated that AAV2 Rep78 and Rep52 interact and inhibit cAMP-dependent protein kinase A (PKA) and its novel homolog PrKX. We hypothesized that modulation of PKA activity by AAV2 may be responsible for inhibition of helper virus replication. In this study we demonstrate that adenovirus replication is sensitive to PKA activity and that AAV2 Rep78/Rep52 proteins contain an inhibitory domain similar to that of the heat-stable PKA inhibitor. This domain, while not directly necessary for AAV2 replication and packaging, is necessary to preserve AAV2 replication fitness during an Ad co-infection. Furthermore, a mutant AAV2 virus lacking this region fails to inhibit adenovirus replication. Thus, inhibition of PKA activity by AAV2 constitutes a novel form of viral interference.
Insights
Adeno-associated virus 2 (AAV2) inhibits helper adenovirus replication by modulating protein kinase A (PKA) activity. A specific inhibitory domain in AAV2 proteins is crucial for this novel viral interference mechanism.
Area of Science:
- Virology
- Molecular Biology
- Cellular Biology
Background:
- Viral interference is a phenomenon where one virus inhibits another's replication.
- Adeno-associated virus 2 (AAV2) requires a helper virus and can interfere with helper virus replication.
- AAV2 Rep proteins (Rep78 and Rep52) were previously shown to inhibit protein kinase A (PKA) and PrKX.
Purpose of the Study:
- To investigate if AAV2's modulation of PKA activity is responsible for inhibiting helper virus replication.
- To determine the role of AAV2 Rep proteins in adenovirus replication and interference.
Main Methods:
- Assessing the sensitivity of adenovirus replication to PKA activity.
- Identifying and characterizing an inhibitory domain within AAV2 Rep78/Rep52 proteins.
- Generating and testing a mutant AAV2 virus lacking the identified inhibitory domain.
Main Results:
- Adenovirus replication is sensitive to PKA activity.
- AAV2 Rep78/Rep52 proteins possess a PKA inhibitory domain, similar to a heat-stable inhibitor.
- This domain is essential for maintaining AAV2 replication fitness during adenovirus co-infection.
- A mutant AAV2 lacking this domain failed to inhibit adenovirus replication.
Conclusions:
- AAV2 inhibits adenovirus replication through the modulation of PKA activity.
- This represents a novel mechanism of viral interference mediated by AAV2.
- The identified inhibitory domain is critical for AAV2's interference capability and replication fitness during co-infection.