Beyond Empty/Full Ratios: Quantifying AAV Capsid Loading Using Mass Photometry

Empty, partially filled and overfilled capsids in gene therapy treatments compete with full capsids for cell entry receptors and stimulate unintended immune responses, diminishing therapeutic efficacy.  To minimize the presence of improperly loaded capsids in AAV samples, it is therefore essential to detect and quantify their presence throughout processing.

Mass photometry is ideal for quantifying AAV capsid loading because it measures the mass of individual particles. It can therefore detect empty vs. partially filled, full and overfilled capsids based on their mass. It is fast and uses low sample volumes and concentrations, meaning it can be used frequently to provide insights throughout workflows.

The SamuxMP, a mass photometer optimized for AAV characterization, can distinguish and quantify AAVs loaded with different amounts of cargo. Now suitable for GMP-compliant environments, it is a reliable, easy-to-use benchtop instrument that is transforming analytical workflows for AAVs.

Key Takeaways