title: Reducing the genotoxic potential of retroviral vectors.
abstract: The recent development of leukemia in gene therapy patients with X-linked severe combined immunodeficiency disease because of retroviral vector insertional mutagenesis has prompted reassessment of the genotoxic potential of integrating vector systems. In this chapter, various strategies are described to reduce the associated risks of retroviral genomic integration. These include deletion of strong transcriptional enhancer-promoter elements in the retroviral long terminal repeats, flanking the retroviral transcriptional unit with enhancer blocking sequences and designing vectors with improved RNA 3' end processing. Protocols are provided to evaluate the relative biosafety of the modified vectors based on their ability to immortalize hematopoietic progenitor cells and propensity to trigger clonal hematopoiesis or leukemogenesis following hematopoietic stem cell transplantation.
authors.affiliation: Department of Anatomy and Regenerative Biology, The George Washington University Medical Center, Washington, DC, USA.
authors.forename: Ali
authors.initials: A
authors.lastname: Ramezani
authors.forename: Teresa S
authors.initials: TS
authors.lastname: Hawley
authors.forename: Robert G
authors.initials: RG
authors.lastname: Hawley
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D000818:Animals; D002478:Cells, Cultured; D004742:Enhancer Elements, Genetic / Q000235:genetics; D005260:Female; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000235:genetics*; D006412:Hematopoietic Stem Cells / Q000502:physiology; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D016254:Mutagenesis, Insertional; D009152:Mutagenicity Tests; D011401:Promoter Regions, Genetic; D012190:Retroviridae / Q000235:genetics*; D020079:Terminal Repeat Sequences / Q000235:genetics; D014161:Transduction, Genetic; D014162:Transfection
chemical_list: D020413:3' Untranslated Regions