Gene Therapy Development: Adeno-Associated Viral (AAV) Capsid Titer with Accurate quantification, Absolute confidence and Validated performance
Producing adeno-associated viral (AAV) vectors on an industrial scale requires accurate measurement of viral capsid concentration in upstream and downstream bioprocessing. Also important is efficiency of time and cost. This post highlights a new solution for simplifying AAV titer determination for gene therapy development.
This article is posted on our Science Snippets Blog
Product information: Dr. Ivan Krylov, Product Manager, Sartorius
Simplifying AAV Capsid Quantitation
Considerable advancement in gene editing and delivery technologies has led to a rapid development of gene therapy strategies for a broad range of disorders, including cancers, hematological conditions, ocular diseases, neuromuscular disease, immunodeficiencies and rare or inherited disorders. To date, the FDA has approved nine gene therapy products for clinical use, with more than 100 candidates in clinical trials.
The AAV vector is one of the most used vectors for gene delivery. However, despite rapid growth in the field, complexity of the AAV production process continues to slow development timelines. We talked with our in-house expert, Dr. Ivan Krylov, Product Manager of Bioanalytical Solutions at Sartorius, about rapid, direct AAV capsid quantitation on the Octet® Bio-Layer Interferometry (BLI) platform.
Why is AAV capsid titer determination important for bioprocessing in gene therapy development? Which technologies are currently used to quantitate AAV capsid titer?
Dr. Krylov: The AAV vector is widely used to deliver genomic material in gene therapy applications. That’s why AAV capsid titer is a critical quality attribute that must be monitored throughout process development and quality control. Common techniques for measuring viral titer include ELISA, HPLC, and ddPCR, but these are time consuming and labor-intensive. We’re addressing these limitations by adding new capabilities to our Octet® Bio-Layer Interferometry (BLI) platform.
Can you describe Octet® BLI technology and how it works?
Dr. Krylov: Octet® BLI systems are used for real-time, label-free analysis of kinetics, affinity and concentration. BLI is an optical technology that uses fiber-optic-based biosensors coated with different chemistries for ligand immobilization. Only molecules binding to or dissociating from the biosensor cause a detectable signal.
The platform is very popular in biotherapeutics development because it simplifies processes. Measurements that ordinarily need high sample volumes, complex setup or excessive time and labor get done quickly and with minimal effort on the Octet® BLI system. The added ability to regenerate the biosensor surface also has cost benefits.
Sartorius recently launched a new Octet® AAVX Biosensor. Can you provide a brief overview of the product?
Dr. Krylov: Our Octet® AAVX Biosensors provide a rapid, label-free and high-throughput method for AAV capsid titer measurement. The biosensors are pre-immobilized with a Biotin-Anti-AAVX Conjugate, which binds with high affinity and specificity to various native and recombinant AAV serotypes, including AAV1 to AAV9 and AAVrh10. Since it is highly specific, you can use it to quantitate AAV capsids in both purified and crude cell culture samples with titer in the range of 8.5E8–1.0E13 vp/mL for most serotypes.
How does the new Octet® AAVX Biosensor compare to other technologies on the market for AAV titer measurement?
Dr. Krylov: ELISA has traditionally been used to measure AAV viral capsid numbers and is often considered the method of choice. But running an ELISA is pretty time consuming; AAV titer measurement using ELISA requires six steps and could take 3–4 hours. Now compare this to the Octet® BLI system, which is one step and gives you data in as little as 15 minutes. You also get data in real time, giving you the ability to monitor and optimize every assay step.
Importantly, we know that AAV titer data on the Octet® BLI system are comparable to ELISA. Our customers provided data in which they tested different AAV serotypes from samples at various steps in their AAV bioprocess workflow and saw good correlation between the Octet® AAVX assay and ELISA. Read more about the study in our Octet® AAVX Biosensors for Rapid and Direct Quantitation of AAV Capsids Application Note.
Are there other applications in AAV and gene therapy where the Octet® BLI platform might play a role in the future?
Dr. Krylov: Our customers will be the key drivers of that. We are always talking with customers about their research and what they need to simplify progress in the lab. We use this information to enhance the capabilities of our existing portfolio and develop new solutions. Since gene therapy is a growing and evolving market, I’m confident that our portfolio will evolve with customer needs and market trends.
To learn more about the Octet® AAVX Biosensors visit the product page, or download the application note below to read about the workflow and see quantification data for multiple AAV serotypes.
