What is MAAP in AAV?

The Membrane-Associated Accessory Protein (MAAP) is a small viral protein encoded by the AAV cap gene that plays a crucial role in the extracellular secretion of AAV particles. It facilitates AAV egress by promoting the association of AAV with extracellular vesicles (EVs) and is loaded onto the surface of these vesicles. Deletion of MAAP significantly reduces AAV secretion, indicating its importance in the process. 

Here’s a more detailed breakdown:

• Egress Factor: MAAP acts as an AAV egress factor, meaning it helps the virus exit the infected cell. 
• EV Association: MAAP promotes the association of AAV with extracellular vesicles, which are membrane-bound sacs released by cells. 
• Secretion Enhancement: By associating with EVs, MAAP enhances the secretion of AAV particles from the cell. 
• Impact on Production: MAAP deletion or modification can affect the kinetics and quantity of AAV secretion, potentially impacting overall AAV production. 
• SNARE Protein Interaction: MAAP interacts with SNARE proteins, which are involved in vesicle trafficking, and this interaction may play a role in the mechanism of MAAP-mediated AAV secretion.