Chapter 6 - HSV Vectors in the Mammalian Brain: Molecular Analysis of Neuronal Physiology, Generation of Genetic Models, and Gene Therapy of Neurological Disorders

Abstract

This chapter discusses mammalian neuronal physiology using herpes simplex virus (HSV) vectors. Several basic principles apply for gene transfer studies of neuronal function. The introduced gene has a dominant phenotype for an effect on cell physiology to be apparent. Retroviruses are used as the primary vector for ex vivo approaches to neurological gene therapy in disease models ranging from Parkinson's and Alzheimer's disease to hereditary neurometabolic disorders. The inherent limitation of retroviral vectors in obtaining efficient and stable gene transfer in neurons has imposed major constraints on in vivo genetic intervention studies in the adult brain. The chapter provides characterization of a defective HSV-1 vector for efficient and stable gene transfer into neurons. In addition to the ability to study dominant positive or dominant negative mutants, the vector-encoded gene can be engineered to direct the protein to specific regions of polarized cells. A nuclear targeting signal can be used to restrict expression to the nucleus, whereas other sequences are used to target dendrites or to axons. Therefore, the vector system is used both to explore the effect of regional expression as well as to help define those sequences critical in the targeting process. HSV amplicon vectors are important to establish that a viral vector approach can complement more established methods to investigate neuronal physiology, to characterize regulation of gene expression in the brain, to generate novel genetic models of neurological diseases, and to increase chances for gene therapy in the nervous system.