Hybrid Yeast-bacteria Cloning System Used to Capture and Modify Adenoviral and Nonviral Genomes

Adenoviral vectors are widely used to express transgenes in vitro and in vivo. A major obstacle to the generation of adenoviral vectors is the manipulation of the large (35 kb) adenoviral genome. We developed a hybrid yeast-bacteria cloning system for the creation of novel adenoviral vectors. The adenovirus 5 (Ad5) genome was cloned into a shuttle vector that contains both yeast and bacterial elements for replication and therefore functions as both a yeast artificial plasmid (YAP) and as a plasmid artificial chromosome (PAC). Any sequence can be introduced into any region of the adenoviral genome via the highly efficient homologous recombination in yeast and then these recombinants are rapidly amplified in bacteria. Adenoviral vectors are generated by introduction of the PAC into the appropriate complementing mammalian cell without the need for plaque purification. Vectors were constructed with deletions in the E1, E3, and/or E4 regions. We have generated more than 100 vectors with a number of different transgenes and regulatory elements. In addition, the YAP/PAC vector was used to capture a DNA fragment encompassing the human factor IX gene, demonstrating the utility of this system to clone and analyze genomic DNA. This novel cloning strategy allows the rapid and versatile construction of adenoviral vectors for gene expression and gene therapy applications.