Cell surface targeting is an attractive strategy to improve efficiency and specificity of gene transfer. However, the implications on the virus-cell-interaction are widely unknown. Our work aims to determine possible risks of this approach and to gain knowledge on the role and function of inserted ligands for the infection process and the intracellular fate of the vectors. Recently, we could demonstrate that the ligand sequence determines whether or not an rAAV targeting vector is able to bind to HSPG, the natural attachment receptor of AAV2. While a binder phenotype was associated with tropism for liver and spleen, and the ability to enter efficiently into various cell types, resembling the phenotype of rAAV2, rAAV targeting vectors with a non-binder phenotype showed a re-directed tropism, and a liver and spleen de-targeting. Here, we continue our studies by determining the influence of non-natural ligand receptor interactions on the mechanism of cell entry, on intracellular processes and on nuclear entry. Non-natural ligand receptor interactions may also influence the fate of the delivered vector genome. We will therefore compare binder and non-binder rAAV targeting vectors regarding the frequency and sites of vector genome integration. Furthermore, the newly developed genetic-chemical targeting technique will be exploited for targeting of stem/progenitor cells.

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