Extensive length and homology dependent chimerism in pool-packaged AAV libraries

Area of Science:

• Molecular Biology
• Gene Therapy
• Virology

Background:

• Adeno-associated viruses (AAVs) are leading gene therapy vectors due to their safety and efficacy.
• Developing functional AAV libraries is crucial for advancing gene therapy research and clinical applications.

Purpose of the Study:

• To investigate the phenomenon of chimerism in complex AAV libraries packaged as a pool.
• To understand the factors influencing chimerism, such as DNA length, homology, and capsid type.

Main Methods:

• Packaging of complex AAV libraries in a pooled format.
• Analysis of packaged AAV genomes to detect and quantify chimerism (barcode swapping).
• Assessment of the relationship between chimerism and factors like insert length and homology.

Main Results:

• Extensive chimerism was observed in pooled AAV libraries, with pervasive barcode swapping affecting a significant portion of packaged genomes.
• Chimerism was found to be dependent on the length and homology of the AAV sequences.
• The observed chimerism was independent of the AAV capsid used for packaging.

Conclusions:

• The packaging process for pooled AAV libraries can lead to significant genomic alterations (chimerism).
• Understanding and mitigating chimerism is essential for accurate AAV library design and reliable gene therapy applications.
• These findings have direct implications for the development and use of AAV-based tools in research and clinical settings.