Executive Summary

Constructing viral vectors that perform both gene replacement and RNAi-mediated knockdown presents unique design and analytical challenges. Successful development requires a strategic approach to plasmid architecture, promoter selection, and the creation of multiplexed potency assays to verify both mechanisms of action. This consultative process de-risks programs by ensuring the vector is manufacturable, stable, and functionally active before committing to large-scale production.

Designing for Bifunctional Activity

For genetic disorders caused by a dominant negative or toxic gain-of-function mutation, a simple gene replacement strategy is insufficient. A successful therapeutic requires both the knockdown of the pathogenic allele and the introduction of a functional copy of the gene. Designing a single AAV vector to accomplish both tasks requires careful consideration of the plasmid construct to avoid compromising vector integrity or function.

The foundational principles of vector construction, such as those explored in the development of novel adenoviral vectors (PMID: 21562118), inform how we approach these complex designs. The stability of the vector genome and its ability to be propagated at high titers are directly linked to the initial plasmid architecture. For dual-function vectors, this means strategically placing the shRNA expression cassette and the transgene cassette to prevent recombination or transcriptional interference, while staying within the AAV packaging capacity.

From Blueprint to Bioreactor

Our process begins with in-silico design and risk assessment, mapping out promoter choices, polyadenylation signals, and the orientation of each genetic element. This phase provides the Strategic Design Guidance Accelerating Development Lifecycles. We then move to small-scale pilot production runs to empirically test the design. A biotech partner recently noted our team has, “Vast knowledge in all aspects of vector production and analytics,” which is a direct result of this rigorous, data-driven approach.

These pilot batches undergo a suite of analytical tests to confirm vector identity, integrity, and purity. Most importantly, we develop and perform functional assays to confirm that the vector can successfully mediate both protein expression and target gene knockdown in vitro. This early validation provides the confidence needed to move forward with process development and scale-up for preclinical studies.