Chapter 2 - Biology of Herpes Simplex Virus (HSV) Defective Viruses and Development of the Amplicon System

Abstract

The herpes simplex virus (HSV) amplicon is a defective virus vector which can be used to introduce foreign genes into eukaryotic cells. Of special relevance concerning the potential use of HSV amplicon vectors for gene transfer into neurons is the fact that the HSV is a neurotropic virus which resides latently in the nerve cell ganglia of humans. In the presence of helper virus, HSV amplicon vectors are packaged as head-to-tail concatemers up to 153 kb in length into defective virus particles. HSV amplicon vectors use the functions of their helper virus to enter, replicate, and express genes in a variety of cells both in vitro, and in vivo, depending on the helper virus and the promoter used in the construct. This chapter first discusses the origin of the amplicon system in studies of naturally occurring defective viral genomes where the delineation of many of the basic virological aspects of the system were first established. Secondly, the chapter discusses the essential cis-acting components that are required and the methods for generating and analyzing high-titer amplicon defective virus stocks. Finally, the chapter discusses some of the first studies in which the HSV amplicon system was used to express a foreign gene and the parameters that affect gene expression in the HSV amplicon system.