Development of Herpes Simplex Virus-based Vectors for Gene Therapy

In recent years, gene and cell therapies have become widely accepted as new therapeutic modalities, and a number of gene therapy drugs have been approved. Underlying this advance are innovations in gene delivery tools, especially viral vectors, which are no longer simply gene transfer tools in basic research. Since its initial inception, all aspects of gene therapy have been dramatically improved, including their safety, functionality, and production technology. On the other hand, with use of gene therapies clinically, new safety and efficacy concerns have emerged, and gene therapy is now entering a new phase. Both preclinical and clinical data have demonstrated that simple overexpression of a therapeutic gene at a disease site through transduction by a gene delivery vector is not sufficient to ensure safety and therapeutic efficacy. Maturation of this field will require more sophisticated gene delivery vector systems and highly regulated therapeutic gene expression systems to precisely introduce these genes into target cells and express them to the appropriate degree at the appropriate time. Herpes simplex virus (HSV)-based vectors are extremely safe and functional vector systems that have the potential to meet current challenges in gene and cell therapy. This makes HSV vectors promising gene delivery vehicles for gene therapy. This chapter will focus on the current trends in the development of HSV as a delivery vector for gene therapy.