Retargeted Foamy Virus Vectors Integrate Less Frequently Near Proto-oncogenes.
Retroviral gene therapy offers immense potential to treat many genetic diseases and has already shown efficacy in clinical trials. However, retroviral vector mediated genotoxicity remains a major challenge and clinically relevant approaches to reduce integration near genes and proto-oncogenes are needed. Foamy retroviral vectors have several advantages over gammaretroviral and lentiviral vectors including a potentially safer integration profile and a lower propensity to activate nearby genes. Here we successfully retargeted foamy retroviral vectors away from genes and into satellite regions enriched for trimethylated histone H3 at lysine 9 by modifying the foamy virus Gag and Pol proteins. Retargeted foamy retroviral vectors integrated near genes and proto-oncogenes less often (p < 0.001) than controls. Importantly, retargeted foamy retroviral vectors can be produced at high, clinically relevant titers (>107transducing units/ml), and unlike other reported retargeting approaches engineered target cells are not needed to achieve retargeting. As proof of principle for use in the clinic we show efficient transduction and retargeting in human cord blood CD34+cells. The modified Gag and Pol helper constructs we describe will allow any investigator to simply use these helper plasmids during vector production to retarget therapeutic foamy retroviral vectors.
Department of Pharmaceutical Sciences, Washington State University, Spokane, WA, 99210, United Sates.
Jonah D
JD
Hocum
Department of Pharmaceutical Sciences, Washington State University, Spokane, WA, 99210, United Sates.
Ian
I
Linde
Department of Pharmaceutical Sciences, Washington State University, Spokane, WA, 99210, United Sates.
Dustin T
DT
Rae
Department of Pharmaceutical Sciences, Washington State University, Spokane, WA, 99210, United Sates.
Casey P
CP
Collins
Department of Pharmaceutical Sciences, Washington State University, Spokane, WA, 99210, United Sates.
Lindsay K
LK
Matern
Department of Pharmaceutical Sciences, Washington State University, Spokane, WA, 99210, United Sates.|School of Molecular Biosciences, Washington State University, Pullman, WA, 99164, United Sates.
Grant D
GD
Trobridge
D002460:Cell Line; D005822:Genetic Vectors; D006801:Humans; D008297:Male; D016133:Polymerase Chain Reaction; D011519:Proto-Oncogenes; D016092:Spumavirus / Q000235:genetics*; D016662:Virus Integration