AvXcel Affinity Resin for Purifying AAV

AvXcel affinity packing employs a completely different ligand strategy—synthetic cyclic peptides—and bonds the ligands to ultra-large pores (200 nm) of rigid synthetic polymethacrylate microspheres. The pore size is much larger than that of AAV viral particles (~25 nm), ensuring that viral particles can fully enter the pores and bind to the ligands, avoiding steric hindrance, and guaranteeing the integrity and binding load during AAV purification. By mimicking the synthetic cyclic peptide ligands of the natural AAV receptor, AvXcel affinity packing recognizes conserved binding sites on the capsids of various serotypes (AAV1-9, rh10, etc.), achieving the platform goal of "one packing covering multiple AAVs," making it suitable for affinity purification of various serotypes of AAV.

Principle of AvXcel Affinity Chromatography for AAV Purification
AvXcel is a serotype-agnostic AAV (adeno-associated virus) affinity chromatography resin developed by Chromagenix. It employs alkaline-stable synthetic peptide ligand affinity chromatography technology and is specifically designed for the purification of AAV gene therapy vectors. Chromagenix has granted Sunresin the exclusive distribution rights for this product in China, Japan, and India. Traditional AAV affinity workflows are limited by serotype specificity, low pH elution, low recovery rates, limited reusability, or the need for development for specific processes, restricting scalability, cost-effectiveness, and ultimately, patient accessibility. AvXcel aims to overcome these limitations and is the first AAV affinity resin to support both acidic and near-neutral elution conditions. Synthetic cyclic peptides are small molecule peptides prepared through chemical synthesis, whose amino acid sequences form a cyclic structure through inter-chain crosslinking.
Mimetic Natural Receptor: This cyclic peptide ligand is designed to mimic the natural cellular receptors for AAVs (such as the HSPG heparin sulfate proteoglycan receptor or AAVR receptor), achieving capture through interaction with conserved binding sites on the AAV capsid protein. Because different AAV serotypes have conserved key receptor-binding domains during evolution, one ligand can recognize multiple serotypes.
Cyclic Structure Contributes Stability: Cyclization eliminates free ends at the N- and C-termini of the peptide chain, making the peptide highly resistant to protease degradation, which is crucial during repeated CIP (clean-in-line) processes.
• Chemical Synthesis Ensures Consistency: Unlike biomanufactured antibody ligands, synthetic cyclic peptides are produced in batches via solid-phase peptide synthesis (SPPS), ensuring extremely high batch-to-batch consistency, no animal-derived components, and compliance with regulatory requirements for gene therapy products.
• Small Molecular Size: Cyclic peptides typically have a molecular weight of only 600–1500 Da (far smaller than the 12–15 kDa of VHH), allowing for higher ligand density on the filler surface, thereby increasing dynamic binding capacity.
• Molecular basis of serotype nonspecificity: Although the overall sequence homology of capsid proteins of different AAV serotypes (AAV19, rh10, etc.) is limited (approximately 60%-80%), they possess conserved three-dimensional structures in key regions involved in receptor binding (such as the receptor-binding interface and hydrophobic pockets). Synthetic cyclic peptide ligands recognize these conserved structural epitopes, rather than linear amino acid sequences, thus enabling "universal" binding to multiple serotypes.

AvXcel affinity filler core advantages:
• Broad-spectrum serotype capture: Universal binding to AAV1–9 and rh10, as well as some engineered serotypes/novel capsid proteins, can be achieved with a single filler, simplifying process development and avoiding repeated validation with multiple fillers.
• Flexible elution window:
- Recommended pH 6.0–6.8 Mild elution: Preserves viral vector integrity and transduction efficacy, no neutralization step required.
- Optional pH 2.5 acidic elution: Compatible with existing platform processes, extending resin life through alkaline CIP (in-situ cleaning).
• High recovery: Vector recovery ≥80%, maintained after ≥60 NaOH cleaning cycles, reducing resin usage and increasing throughput.
• Excellent impurity removal capability:
Host cell protein (HCP) removal rate LRV 2.2–3.4, DNA (hcDNA) and host DNA (pDNA) removal rate LRV 3.0–3.5.
• Alkali resistance: Demonstrated >50 cycles (target 100+ cycles) under 0.1 M NaOH, 15-minute contact time conditions, supporting process scale-up and GMP-compliant production.
• Scalability and GMP Readiness: Supporting a truly platform-based process in the field of gene therapy.

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Background

AAV (adeno-associated virus) is a viral vector widely used in gene therapy. Its particle size is only about 25 nm, and its concentration in cell lysates is typically low (10¹¹~10¹³ vg/mL), while the concentration of impurities (host cell protein HCP, host cell DNA hcDNA, empty capsids, cell debris, etc.) is several orders of magnitude higher. Therefore, a highly selective and efficient capture chromatography step is needed. Traditional affinity chromatography resins are based on camel-derived VHH single-domain antibody fragments, capturing AAV through antibody-antigen specific recognition. Traditional AAV purification affinity packing material technology has several limitations:
• Different serotypes have significant differences in the surface antigen epitopes of capsid proteins, making it difficult for a single antibody to cover all serotypes.
• Elution requires strongly acidic conditions at pH 2.5~3.0, leading to conformational changes in capsid proteins, viral aggregation, and loss of transduction activity.
• Antibody ligands are expensive, and batch-to-batch consistency is affected by biomanufacturing processes.