title: Reduced genotoxicity of avian sarcoma leukosis virus vectors in rhesus long-term repopulating cells compared to standard murine retrovirus vectors.
abstract: Insertional mutagenesis continues to be a major concern in hematopoietic stem-cell gene therapy. Nonconventional gene transfer vectors with more favorable integration features in comparison with conventional retrovirus and lentivirus vectors are being developed and optimized. In this study, we report for the first time a systematic analysis of 198 avian sarcoma leukosis virus (ASLV) insertion sites identified in rhesus long-term repopulating cells, and a comparison of ASLV insertion patterns to Moloney murine leukemia virus (MLV) (n = 396) and simian immunodeficiency virus (SIV) (n = 289) using the newly released rhesus genome databank. Despite a weak preference toward gene-coding regions, ASLV integration is nonclustered, does not favor gene-rich regions, transcription start sites, or CpG islands. There was no propensity for ASLV insertions within or near proto-oncogenes, and most importantly, no insertions close to or within the Mds1-Evi1 locus, which is in contrast to the significant over-representation of this insertion site for MLV vectors in the same transplantation model. Furthermore, ASLV long terminal repeats (LTRs) do not have detectable promoter and enhancer activity in a quantitative luciferase assay to measure neighboring gene activation. The combination of these features is unique for ASLV and suggests that optimized vectors based on this virus could be useful and safe for gene transfer to hematopoietic stem cells and progenitor cells.
authors.affiliation: Molecular Hematopoiesis Section, Hematology Branch, National Heart, Lung, Blood Institute, National Institute of Health, Bethesda, Maryland, USA.
authors.forename: Jingqiong
authors.initials: J
authors.lastname: Hu
authors.forename: Gabriel
authors.initials: G
authors.lastname: Renaud
authors.forename: Theotonius J
authors.initials: TJ
authors.lastname: Gomes
authors.forename: Theotonius
authors.initials: T
authors.lastname: Golmes
authors.forename: Andrea
authors.initials: A
authors.lastname: Ferris
authors.forename: Paul C
authors.initials: PC
authors.lastname: Hendrie
authors.forename: Robert E
authors.initials: RE
authors.lastname: Donahue
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Hughes
authors.forename: Tyra G
authors.initials: TG
authors.lastname: Wolfsberg
authors.forename: David W
authors.initials: DW
authors.lastname: Russell
authors.forename: Cynthia E
authors.initials: CE
authors.lastname: Dunbar
mesh_terms: D000818:Animals; D001354:Avian Leukosis Virus / Q000235:genetics*; D001358:Avian Sarcoma Viruses / Q000235:genetics*; D002645:Chickens; D018899:CpG Islands / Q000235:genetics; D004742:Enhancer Elements, Genetic / Q000235:genetics; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism / Q000821:virology; D005822:Genetic Vectors / Q000235:genetics*; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D006801:Humans; D008253:Macaca mulatta / Q000235:genetics; D051379:Mice; D008979:Moloney murine leukemia virus / Q000235:genetics*; D015514:Oncogene Proteins, Fusion / Q000235:genetics; D015302:Simian Immunodeficiency Virus / Q000235:genetics; D020079:Terminal Repeat Sequences / Q000235:genetics; D024363:Transcription Initiation Site; D014158:Transcription, Genetic; D014161:Transduction, Genetic; D016662:Virus Integration
chemical_list: C490909:MDS1-EVI1 fusion protein, mouse; D015514:Oncogene Proteins, Fusion