Our Engineered Veto© therapy requires a transfer vehicle (vector); however, existing vectors present limitations. Retroviruses, for instance, often cause cancer. Associated adenoviral vectors (AAV) are efficient but with very limited payload. Adenoviral virus vectors would be the most efficient vehicle to deliver therapeutic genes. However, earlier versions of these vectors carried numerous viral genes required for efficient packaging, thereby attracting dangerously vigorous immune responses. When all viral genes were removed immune interference subsided, but it became necessary to employ a helper virus to efficiently manufacture fully deleted adenoviral vectors. As helper viruses are considered contaminants in preparations of fully deleted adenoviral vectors, they prevented their use in patients.

Our scientists designed a novel adenoviral architecture that allows the manufacture of fully-deleted adenoviral vectors without the use of helper viruses. We resolved the issue of helper virus contamination, thereby preventing any contamination with replication-efficient viral recombinants.

These efforts led to the creation of a fully deleted, helper-independent adenoviral vector (fdhiAd), the final version of this promising vector line. This virus and its associated packaging cell line (the GrE-3© cell line),represent a novel, successful therapy system. The FDHI Virus and its GrE-3© cell line are the baseline for all viral therapies. This flexible, powerful "operating system" forms the foundation of Greffex’s gene therapy, veto engineering and vaccine vector therapies.