
AAVs
AAVs are non-pathogenic versions of the adeno-associated virus that are re-packaged with genetic material to use for gene therapy. AAVs are proteinaceous capsids that are made up of 3 different proteins called viral protein 1, 2, and 3. The ratio of viral proteins defines the capsid serotype and the tissue that it will target. A typical AAV is about 25 nm and holds about 5 kb of single-stranded DNA. Some of the difficulties in characterizing AAVs include the size of the three- part viral protein complex and the variability of the payload composition (full, empty and/or partial).
Microfluidic Modulation Spectroscopy (MMS) is useful in analyzing AAVs because it provides a direct measurement of both proteins and nucleic acids, enabling the simultaneous characterization of the capsid and payload. This can be applied to determining empty-full ratios, one of the key measurements in AAV quantitation. Utilizing the protein structure capabilities, the Apollo and AQS³pro can also be used to determine the structure and stability of the capsid under manufacturing stress conditions. Lastly, addressing the limited source material, MMS is a non-destructive technique, allowing recovery of the samples and providing the ability for the samples to be recovered and analyzed with orthogonal biophysical techniques.