Adeno-associated virus (AAV) analysis from titer to payload: Chromatography-based solutions
What are AAVs
Adeno-associated viruses are non-pathogenic viruses that are used as gene-delivery tools for gene-therapies. For that, it is taken advantage of AAVs transferring their genetic material into dividing and quiescent cells. The transferred gene is translated into proteins by the cell's translation machinery, but does not integrate into the genome. Thus, the genetic material is not passed on to daughter cells and is mainly used for cell types that do not divide. This way, non-functional or missing proteins resulting from genetic defects can be replaced.
How is an AAV structured and which characteristics are important?
An AAV particle is made up of a protein shell and the payload. The protein shell (capsid) is formed from three viral proteins that come together to form the icosahedral particle. This envelops the genetic material: single-stranded DNA, which in wild-type viruses encodes for capsid proteins and in therapeutically used AAVs for the protein of interest.
- Important characteristics to analyze in AAVs:
- Analyzable by chromatographic methods:
- Titer (SEC-MALS)
- Full-empty-ratio (Anion-exchange, SEC-MALS and UV)
- Purity (SEC-MALS)
- Analyzed by non-chromatographic methods
- Identity of the genetic material (e.g. qPCR)