AAV-Q Platform for rcAAV Assay
Introduction
AAV continues to lead the field of in vivo gene delivery, vector safety and regulatory compliance have never been more critical. Among the key concerns during AAV vector production is the potential generation of replication-competent AAV (rcAAV) — a rare but significant contaminant that can compromise therapeutic safety, product quality, and clinical trial outcomes. The Food and Drug Administration (FDA) requires that AAV products be screened for rcAAVs to ensure the safety of gene therapy products.
At AAVnerGene, we developed AAV-Q Platform, which works for for both AAV TCID50 and rcAAV assay.
What Is rcAAV?
rcAAV (replication-competent AAV) refers to AAV particles that have regained the ability to replicate in the presence of a helper virus (e.g., adenovirus). It is wild-type like AAV. This can occur unintentionally during AAV vector manufacturing, typically due to recombination events between plasmids encoding AAV Rep and Cap genes and the ITR-flanked transgene.
Although rcAAV is rare in well-optimized systems, its presence poses several concerns:
Uncontrolled replication in vivo (especially in immunocompromised hosts)
Potential integration into host genomes
Increased immunogenicity
Regulatory non-compliance
AAV-Q Platform
The AAV-Q Platform includes three specialized cell lines, two quantitative assays, and one adenoviral vector, providing a complete and standardized system for AAV infectivity and rcAAV analysis.
Three Cell Lines:
- HEK293R: AAVR overexpression based on HEK 293A cells;
- HEK293RR: Rep overexpression based on HEK 293R cells;
- HEK293Rd: Optimized for Rd-Ad5 production;
One Ad vector:
- Rd-Ad5：Replication deficient in HEK 293A, but not in HEK293Rd cells;
Two Assays:
- AAV TCID50 Assay: Measures AAV potency or infectious titer using HEK293RR cells with Rd-Ad5;
- rcAAV Assay: Detects replication-competent AAVs using HEK293R cells with Rd-Ad5;
Key Features of AAVnerGene's rcAAV assay
- Ultra-sensitive: Detects a single-copy;
- Quick results: Turnaround within one week;
- Broadly compatible: works with most AAV serotypes;
- Safe design: Uses Rd-Ad5 instead of wtAd5;
- Cost-efficient: streamlined qPCR workflow;
- Highly consistent: Controlled assay conditions;
- Reliable & robust: Low variability and high reproducibility;
Products and Services of rcAAV assay
| Products/Services | Specification | Price | Order |
| HEK293R | HEK293A stably expression AAVR gene | License | In stock |
| Rd-Ad5 | ≥1E8 TU/ml, 100 μl, Replication deficient in HEK293 cell | $1999 | In stock |
| rcAAV assay | Full scale of rcAAV assay and report | $5000 | 2-3 weeks |
rcAAV assay service at AAVnerGene
This service is for customers who need accurate rcAAV titer of the AAV virus for research and therapeutic purpose. The FDA’s recommended level for rcAAV in AAV products is generally less than 1 rcAAV per 1e8 vector genomes, according to Regulations.gov.
Information Requested from the Client:
- Estimated AAV vector titer (vg/mL or GC/mL)
- 50 μL of sample is preferred; a minimum of 10 μL is required.
- AAV rep and capsid information or qPCR/ddPCR primer and probe sequences
rcAAV assay protocol and calculation
The rcAAV assay follows a protocol and calculation method that are similar to those of the AAV TCID₅₀ assay. However, a much smaller dilution factor is required because AAV samples typically contain fewer than one infectious rcAAV per 10⁸ vector genomes.