Adeno-Associated Virus Host Cell Protein Profiling Using Micro-flow Separation on a UHPLC-HRAM MS Platform

Significance of the Topic

Recombinant adeno-associated virus (rAAV) vectors are critical for gene therapy, offering high transduction efficiency and safety. Monitoring host cell protein (HCP) impurities is essential to ensure product safety and efficacy. Given that many AAVs are produced in human cell lines with complex proteomes, sensitive analytical methods are required to detect and quantify low-level HCPs throughout biomanufacturing.

Study Objectives and Overview

This work aimed to develop a robust micro-flow UHPLC-HRAM MS/MS method to profile and relatively quantify residual HCPs in crude harvest and purified AAV6 samples. The approach combines micro-flow separation with high-resolution Orbitrap mass spectrometry and advanced data processing for comprehensive HCP analysis.

Methodology and Instrumentation

Enzymatic digestion with trypsin was performed on crude harvest and purified AAV6 samples spiked with a Streptococcus protein standard. Separation used a Thermo Scientific Vanquish Horizon UHPLC system with a PepMap 100 C18 column (1.0×150 mm, 3 µm) at 50 °C and 80 µL/min flow, employing a water/acetonitrile gradient with 0.1% formic acid. MS detection was carried out on a Thermo Scientific Orbitrap Exploris 480 with data-dependent MS/MS acquisition. Data processing utilized Thermo Scientific Biopharma Finder 5.0 software and the Human UniProt-proteome database for HCP identification.

Main Results and Discussion

• In the crude harvest AAV6 sample, nearly 1 000 HCPs were identified with at least three unique peptides, demonstrating the method’s high sensitivity.
• After POROS AAVX affinity purification, HCP identifications dropped to 30 proteins, confirming efficient impurity removal.
• The method exhibited excellent retention time reproducibility and integrated peak area precision (CV ~11% for low-abundance peptides).
• Low-level HCPs, such as myristoylated alanine-rich C-kinase substrate, were confidently identified and quantified at estimated concentrations around 3.6 pmol/mL.

Benefits and Practical Applications

This micro-flow UHPLC-MS/MS approach delivers:

• Enhanced sensitivity for low-abundance HCP detection in complex matrices.
• High throughput and robustness compatible with routine QC workflows.
• Precise relative quantification enabling comparison between process stages.
• Comprehensive HCP profiling to support process optimization and regulatory compliance.

Future Trends and Possibilities for Application

• Expansion to other viral vectors and cell-derived biologics requiring stringent impurity control.
• Integration of real-time data sharing via cloud-based platforms for collaborative review.
• Development of targeted HCP panels for streamlined QC assays.
• Application of machine learning to predict purification efficacy and impurity profiles.

Conclusion

The developed micro-flow UHPLC-HRAM MS/MS method demonstrated high sensitivity, reproducibility, and effective relative quantification of HCPs in AAV6 samples. Coupled with Biopharma Finder data processing, this workflow supports comprehensive characterization and control of process-related impurities in gene therapy products.

Reference

Reiko Kiyonami et al., "Adeno-Associated Virus Host Cell Protein Profiling Using Micro-flow Separation on a UHPLC-HRAM MS Platform," Thermo Fisher Scientific, 2021.