Executive Summary

The quality of plasmid DNA used in the triple-transfection process is a primary determinant of final AAV vector yield, purity, and functional titer. For German and EU-based research programs targeting ATMP submissions, controlling plasmid quality attributes like supercoiled content, endotoxin levels, and sequence integrity is a direct method for de-risking the path to IND/IMPD-enabling activities. Inconsistent starting materials directly correlate with production failures, batch-to-batch variability, and downstream analytical challenges.

The Role of Plasmid DNA in AAV Vector Manufacturing

The production of recombinant AAV (rAAV) vectors via transient transfection of HEK293 cells is a well-established process. Its success is highly dependent on the quality and consistency of the three plasmid components: the ITR-containing vector plasmid, the Rep/Cap plasmid, and the helper plasmid. Any deviation in the quality of these inputs can have cascading negative effects on the entire production run, impacting timelines and resource allocation for research institutes across Germany and the EU.

Key plasmid quality attributes that directly influence AAV production outcomes include:

• Purity: Freedom from contaminating bacterial host genomic DNA and proteins.

• Topology: A high percentage of the supercoiled isoform for efficient nuclear delivery.

• Homogeneity: Absence of plasmid multimers or degradation.

• Identity: Verified sequence integrity of the gene of interest, ITRs, and other functional elements.

Mitigating Immunogenicity and Ensuring In Vivo Performance

The quality of the starting plasmid material has direct implications for the safety and efficacy profile of the final AAV vector. Impurities within a plasmid preparation can be co-packaged or can persist through purification, potentially contributing to the vector’s overall immunogenicity profile. As noted in reviews of AAV as an immunogen, multiple factors can influence host immune responses, and minimizing process-related impurities is a key mitigation strategy (PMID: 17979679).

Achieving predictable in vivo performance requires controlling all sources of variability. While host factors like pre-existing immunity can impact biodistribution and gene expression (PMID: 19888196), the process begins with a well-characterized vector. Ensuring the input plasmid is sequence-perfect and structurally sound is the first step toward producing a vector that behaves consistently in complex biological systems.

We started collaborating with UPenn Vector core in 2023 and the AAV vector which they manufactured laid a foundation for development of a gene therapy candidate which will enter soon preclinical studies. The key people from UPenn Vector Core joined Franklin Biolabs and our partnership transitioned without interruption from UPenn Vecor Core to Franklin Biolabs Research Vector Division. Franklin Biolabs provides the essential vector manufacturing support for our AAV-vector based gene therapy candidate development, and we hope to continue the partnership for years to come.
— Biotech Partner

A Data-Driven Approach to Research Vector Production

At our >100,000 sq ft facility, we leverage decades of experience manufacturing AAV, Lentivirus, and Adenovirus vectors to support advanced therapy programs. This expertise, which has contributed to a 100% successful IND submission rate for programs we have supported since 2019, begins with rigorous quality control of all starting materials. Franklin Biolabs launched in 2024, carrying forward the team and technical knowledge from the Penn Vector Core to provide this continuity.

Our process ensures that every batch of plasmid DNA used for research vector production is characterized for the attributes that matter for a successful outcome. This focus on input materials is a core component of how we enable sponsors to move from candidate to IND within an 18-24 month timeline.

For more information on our AAV packaging services, please see our primary service page here.