Strategies to accomplish targeted gene delivery to muscle cells employing tropism-modified adenoviral vectors

We are developing strategies to modify the tropism of adenoviral vectors to accomplish targeted transduction of muscle cells for DMD gene therapy. In one approach, we have introduced targeting ligands into the adenovirus fibre, which mediates the binding of the virus Ad5 to the primary cellular receptor. In order to incorporate these fibre-ligand fusions into recombinant adenoviral vectors, we have employed a method based upon homologous DNA recombination between a fibre-deleted, propagation-defective rescue plasmid and a shuttle plasmid encoding a variant fibre. To date, we have generated an adenoviral vector containing chimeric fibres composed of the tail and shaft domains of adenovirus serotype 5 and the knob domain of serotype 3. This modification altered the receptor recognition profile of the virus containing the fibre chimera. In an alternative approach to the generation of a targeted adenoviral vector, we conjugated folate to the neutralising Fab fragment of an anti-fibre monoclonal antibody. This Fab-folate conjugate was shown to redirect adenoviral infection of target cells via the folate receptor at a high efficiency. These studies suggest that it will be possible to achieve our goal of deriving targeted adenoviral vectors for muscle cell-specific gene delivery in vivo.