The goal of Project 2 is to study the efficacy and safety of hematopoietic stem cell (HSC) gene therapy for severe combined immunodeficiency (SC1D-X1) using FV vectors in the canine model of SCID-X1. Studies in human patients have shown that insertional mutagenesis is a substantial concern in the treatment of SCID-X1 with HSC gene therapy. The canine SCID-X1 model is an outstanding large animal model to test novel gene therapy and transplantation strategies for the treatment of SC1D-X1. The canine X-linked SCID syndrome, just as in humans, is caused by mutations in the common gamma subunit (?c) of the IL-2, IL-4, IL-7, IL-9 and lL-15 receptors. As in humans, neonatal dogs with SCID-X1 have few peripheral T cells, and the number of peripheral B cells is increased. B cells in canine SCID-X1 are able to produce IgM but are not capable of class-switching to IgG antibodies. The canine SCID-X1 model has been extensively used to study bone marrow transplantation and gene therapy strategies. A major strength of canine studies is the ability to perform long-term evaluations of efficacy and safety. Here we propose to study novel FV vectors and nonmyeloablative conditioning to improve efficacy and safety of gene therapy for SCID-X1. We hypothesize that FV vectors will provide a safer integration site profile in SCID-X1 dogs similar to our preliminary data in normal dogs. We further hypothesize that novel nonmyeloablative conditioning regimens will improve engraftment of gene-corrected HSCs and thus improve long-term immune reconstitution. Furthermore, we test the hypothesis that in vivo administration of FV vectors may improve immune reconstitution. Project 2 will interact closely with all other projects and cores. Specifically, Project 2 will closely work with Drs. Rawlings and Scharenberg who will evaluate FV vectors in the mouse model in Project 1. We will also closely work with Dr. Trobridge, Project Leader of Project 3, to evaluate novel integration site analyses and potentially improved, insulated FV vectors. We will utilize all cores. Core A will facilitate communication among the different projects and cores, Core B will provide all FV vectors. Core C will assist with studies to evaluate immune reconstitution in SCID-X1 dogs, and Core D will assist with the FV vector integration site analyses.

Public Health Relevance

The goal of Project 2 is to study the efficacy and safety of hematopoietic stem cell (HSC) gene therapy for severe combined immunodeficiency (SCID-X1) using foamy virus vectors. The proposed studies introduce several novel concepts that may change current research or clinical practice paradigms for the treatment of this inherited X-linked disorder of the immune system.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Program Projects (P01)
Project #
Application #
Study Section
Special Emphasis Panel (ZAI1)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Seattle Children's Hospital
United States
Zip Code
Browning, D L; Everson, E M; Leap, D J et al. (2017) Evidence for the in vivo safety of insulated foamy viral vectors. Gene Ther 24:187-198
Singh, Swati; Khan, Iram; Khim, Socheath et al. (2017) Safe and Effective Gene Therapy for Murine Wiskott-Aldrich Syndrome Using an Insulated Lentiviral Vector. Mol Ther Methods Clin Dev 4:1-16
Browning, Diana L; Trobridge, Grant D (2016) Insulators to Improve the Safety of Retroviral Vectors for HIV Gene Therapy. Biomedicines 4:
Browning, Diana L; Collins, Casey P; Hocum, Jonah D et al. (2016) Insulated Foamy Viral Vectors. Hum Gene Ther 27:255-66
Bii, Victor M; Trobridge, Grant D (2016) Identifying Cancer Driver Genes Using Replication-Incompetent Retroviral Vectors. Cancers (Basel) 8:
Nalla, Arun K; Williams, Theodore F; Collins, Casey P et al. (2016) Lentiviral vector-mediated insertional mutagenesis screen identifies genes that influence androgen independent prostate cancer progression and predict clinical outcome. Mol Carcinog 55:1761-1771
Humbert, Olivier; Gisch, Don W; Wohlfahrt, Martin E et al. (2016) Development of Third-generation Cocal Envelope Producer Cell Lines for Robust Lentiviral Gene Transfer into Hematopoietic Stem Cells and T-cells. Mol Ther 24:1237-46
Everson, Elizabeth M; Olzsko, Miles E; Leap, David J et al. (2016) A comparison of foamy and lentiviral vector genotoxicity in SCID-repopulating cells shows foamy vectors are less prone to clonal dominance. Mol Ther Methods Clin Dev 3:16048
Hocum, Jonah D; Linde, Ian; Rae, Dustin T et al. (2016) Retargeted Foamy Virus Vectors Integrate Less Frequently Near Proto-oncogenes. Sci Rep 6:36610
Nalla, Arun K; Trobridge, Grant D (2016) Prospects for Foamy Viral Vector Anti-HIV Gene Therapy. Biomedicines 4:

Showing the most recent 10 out of 39 publications