title: A novel gene therapy strategy using secreted multifunctional anti-HIV proteins to confer protection to gene-modified and unmodified target cells.
abstract: Current human immunodeficiency virus type I (HIV) gene therapy strategies focus on rendering HIV target cells non-permissive to viral replication. However, gene-modified cells fail to accumulate in patients and the virus continues to replicate in the unmodified target cell population. We have designed lentiviral vectors encoding secreted anti-HIV proteins to protect both gene-modified and unmodified cells from infection. Soluble CD4 (sCD4), a secreted single chain variable fragment (sscFv(17b)) and a secreted fusion inhibitor (sFI(T45)) were used to target receptor binding, co-receptor binding and membrane fusion, respectively. Additionally, we designed bi- and tri-functional fusion proteins to exploit the multistep nature of HIV entry. Of the seven antiviral proteins tested, sCD4, sCD4-scFv(17b), sCD4-FI(T45) and sCD4-scFv(17b)-FI(T45) efficiently inhibited HIV entry. The neutralization potency of the bi-functional fusion proteins sCD4-scFv(17b) and sCD4-FI(T45) was superior to that of sCD4 and the Food and Drug Administration-approved fusion inhibitor T-20. In co-culture experiments, sCD4, sCD4-scFv(17b) and sCD4-FI(T45) secreted from gene-modified producer cells conferred substantial protection to unmodified peripheral blood mononuclear cells. In conclusion, continuous delivery of secreted anti-HIV proteins via gene therapy may be a promising strategy to overcome the limitations of the current treatment.
authors.affiliation: Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Falkenhagen
authors.affiliation: Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Ameli
authors.affiliation: Department of Pediatrics, The Hospital for Sick Children, Toronto, ON, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Asad
authors.affiliation: 1] Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada [2] Department of Pediatrics, The Hospital for Sick Children, Toronto, ON, Canada.
authors.forename: S E
authors.initials: SE
authors.lastname: Read
authors.affiliation: 1] Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada [2] Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Joshi
mesh_terms: D019380:Anti-HIV Agents / Q000494:pharmacology*; D000911:Antibodies, Monoclonal / Q000235:genetics / Q000494:pharmacology; D001688:Biological Products / Q000494:pharmacology; D015704:CD4 Antigens / Q000235:genetics / Q000494:pharmacology*; D045744:Cell Line, Tumor; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000008:administration & dosage; D057809:HEK293 Cells; D023581:HIV Fusion Inhibitors / Q000494:pharmacology*; D015497:HIV-1 / Q000187:drug effects*; D006801:Humans; D016086:Lentivirus / Q000235:genetics*; D057127:Single-Chain Antibodies / Q000235:genetics / Q000494:pharmacology; D014481:United States; D014486:United States Food and Drug Administration
chemical_list: D019380:Anti-HIV Agents; D000911:Antibodies, Monoclonal; D001688:Biological Products; D015704:CD4 Antigens; D023581:HIV Fusion Inhibitors; D057127:Single-Chain Antibodies