An Improved Helper Plasmid Containing Deletions Within the E4 and E2a Genes Results in Increased Adeno-Associated Virus Productivity.

The use of a helper plasmid to replace adenovirus infection for adeno-associated virus (AAV) manufacturing has been common practice for decades. Adenovirus E4, E2a, and VA RNA genes are sufficient to support efficient AAV replication. In an effort to ensure that all transfected DNA has a functional role in AAV production, deletions were introduced to the E4 and E2a genes to determine if any portions were dispensable. Although a 900 bp deletion in the E2a intron did not have an impact, the removal of open reading frames (orf) 1-4 from the E4 gene resulted in a doubling of AAV productivity. The E4Δorf1-4 deletion was associated with a reduction in E4orf6 transcripts, along with an increase in Rep and Cap transcripts and protein levels, which corresponded to increased AAV productivity in crude lysate. The final product of these studies was a helper plasmid, termed OXB-Helper_3, that is >3.4 kb smaller than the original control plasmid and resulted in ∼2× improvement in vector genome productivity across multiple capsid serotypes, genome designs, and transfection platforms.

A novel dual-plasmid platform provides scalable transfection yielding improved productivity and packaging across multiple AAV serotypes and genomes.

Transient transfection of mammalian cells using plasmid DNA is a standard method to produce adeno-associated virus (AAV) vectors allowing for flexible and scalable manufacture. Typically, three plasmids are used to encode the necessary components to facilitate vector production; however, a dual-plasmid system, termed pDG, was introduced over 2 decades ago demonstrating two components could be combined resulting in comparable productivity to triple transfection. We have developed a novel dual-plasmid system, pOXB, with an alternative arrangement of sequences that results in significantly increased AAV vector productivity and percentage of full capsids packaged in comparison to the pDG dual design and triple transfection. Here, we demonstrate the reproducibility of these findings across seven recombinant AAV genomes and multiple capsid serotypes as well as the scalability of the pOXB dual-plasmid transfection at 50-L bioreactor scale. Purified drug substance showed a consistent product quality profile in line with triple-transfected vectors, except for a substantial improvement in intact genomes packaged using the pOXB dual- transfection system. Furthermore, pOXB dual- and triple-transfection-based vectors performed consistently in vivo. The pOXB dual plasmid represents an innovation in AAV manufacturing resulting in significant process gains while maintaining the flexibility of a transient transfection platform.

YAP vs. TAZ: differences in expression revealed through rigorous validation of target-specific monoclonal antibodies.

The ability to reproduce scientific findings is foundational in research; yet, it is compromised in part by poorly characterized reagents, including antibodies. In this report, we describe the application of complementary validation strategies tailored for use in immunohistochemical assays in the characterization of rabbit monoclonal antibodies against YAP and TAZ, homologous and sequentially similar transcriptional effectors of the Hippo signaling pathway. A lack of antibody reagents rigorously validated for immunohistochemistry has limited the Hippo signaling research community's ability to interrogate YAP and TAZ independently in tissue. In a series of normal and diseased human tissues, we were able to demonstrate differential expression patterns of YAP and TAZ, suggesting the potential for functional differences of these proteins. These differences can now be studied in greater detail with these highly validated tools.