Gene therapy with herpes simplex virus vectors: progress and prospects for clinical neuroscience.

Gene delivery to the nervous system represents perhaps the ultimate challenge of gene therapy in view of the complexity of this system, the wide variety of intractable neurological diseases, and the need to deliver the gene to nondividing cells. Although a variety of systems for such gene delivery are under development, herpes simplex virus has unique advantages in terms of its large genome size and its ability to naturally enter a latent state in neuronal cells. Considerable progress has been made in the effective disablement of this virus while retaining its ability to deliver genes and in producing long-term expression of the foreign gene. It is likely that these viruses may ultimately be of use in human gene therapy procedures for otherwise intractable neurological diseases such as Parkinson's disease.