For a safe and successful gene therapy approach the therapeutic payload needs to be efficiently transduced and maintained in the target cell without side effects. However, history taught us that the risk of genotoxicity due to insertional mutagenesis needs to be evaluated and that alternative genetic elements for maintenance of the transgene need to be explored. Herein, we plan to investigate novel viral hybrid-vectors which combine high transduction efficiencies of adenovirus and adeno-associated virus (AAV) with improved genetic elements for stable transduction.
Over the recent years we established pre-conditions for the first prototypes of these hybrid-vector systems utilizing the phiC31 integrase for limited integration sites and the Sleeping Beauty transposase for somatic integration. Within the following three years the goal is to (1) evaluate a 100-fold improved transposon system which will be transduced into the target cell using an adenoviral or an AAV vector. To avoid genotoxicity we plan to (2) deliver the episomally maintained plasmid replicon pEPI using adenovirus. To improve the safety profile of the phiC31 integrase system we are aiming at (3) analyzing specificity of integration of our novel phiC31 integrase mutants. Finally, we will (4) analyze efficacy of these novel systems in vitro and in vivo.

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