CHAPTER 25 - Retroviral Vectors

Abstract

This chapter describes retroviruses as the RNA viruses whose life cycle includes their replication by a DNA intermediate that integrates into the host genome. Transcription of the provirus leads to the production of virions without any apparent cytopathic effect on the cells. The demonstration that transfection of a cloned DNA copy of a retrovirus leads to the production of infectious virions indicated that retroviruses could be used as vectors for introducing DNA into eukaryotic cells. However, the definitive demonstration has been performed by inserting the herpes simplex thymidine kinase gene into a proviral copy of either the spleen necrosis virus or the Harvey murine sarcoma virus. One of the major advantages of retroviruses over DNA viruses is that, for most of them, integration into the host chromosome is an obligate step in their life cycle. The integration mechanism leads to the provirus having a specific structure in which the genomic organization is conserved.