Adenovirus vectors with the 100K gene deleted and their potential for multiple gene therapy applications

The 100K protein has a number of critical roles vital for successful comple tion of the late phases of the adenovirus (Ad) life cycle. We hypothesized that the introduction of deletions within the 100K gene would allow for the production of a series of nerv classes of Ad vector, including one that is replication competent but blocked in the ability to carry out many late-ph ase Ad functions. Such a vector would have potential for several gene thera py applications, based upon its ability to increase the copy number of the transgene encoded by the vector (via genome replication) while decreasing t he side effects associated with Ad late gene expression. To efficiently pro duce 100K-deleted Ad ([100K-]Ad) vectors, an E1- and 100K-complementing cel l line (K-16) was successfully isolated, Transfection of an [E1-,100K-]Ad v ector genome into the K-16 cells readily yielded high titers of the vector. After infection of noncomplementing cells, we demonstrated that [100K-]Ad vectors have a significantly decreased ability to express several Ad late g enes. Additionally, if the El gene was present in the infected noncomplemen ting cells, [100K-]Ad vectors were capable of replicating their genomes to high copy number, but were significantly blocked in their ability to effici ently encapsidate the replicated genomes. Injection of an [E1-,100K-]Ad vec tor in vivo also correlated with significantly decreased hepatotoxicity, as well as prolonged vector persistence. In summary, the unique properties of [100K-]Ad vectors suggest that they may have utility in a variety of gene therapy applications.