Viral vectors for gene therapy in Parkinson's disease

The ability of transplanted neurons from aborted foetuses to produce some therapeutic benefit in Parkinson's disease makes this disease an obvious target for the development of gene therapy procedures which involve delivering the same factors as are provided by the foetal neurons but using a reagent which could be produced in large amounts in a standardised manner. This approach could involve both the delivery of the gene encoding tyrosine hydroxylase to boost dopamine production or the delivery of genes encoding neurotrophic factors such as GDNF to promote the survival of dopaminergic neurons. A variety of different viral and non-viral methods for achieving such gene delivery has been described. These are discussed together with the particular advantages of herpes simplex virus-based vectors which have the potential to deliver multiple therapeutic genes in a single virus vector.