title: Efficient Tet-dependent expression of human factor IX in vivo by a new self-regulating lentiviral vector.
abstract: Regulation of gene expression represents a long-sought goal of gene therapy. However, most viral vectors pose constraints on the incorporation of drug-dependent transcriptional regulatory systems. Here, by optimizing the design of self-regulating lentiviral vectors based on the tetracycline system, we have been able to overcome the limitations of previously reported constructs and to reach both robust expression and efficient regulation from a single vector. The improved performance allows us to report for the first time effective long-term in vivo regulation of a human clotting Factor IX (hF.IX) transgene upon systemic administration of a single vector to SCID mice. We showed that hF.IX expression in the plasma could be expressed to therapeutically significant concentrations, adjusted to different set levels by varying the tetracycline dose, rapidly turned off and on, and completely recovered after each treatment cycle. The new vector design was versatile, as it successfully incorporated a tissue-specific promoter that selectively targeted regulated expression to hepatocytes. Robust transgene expression in the systemic circulation coupled to the ability to switch off and even adjust the expression level may open the way to safer gene-based delivery of therapeutics.
authors.affiliation: Institute for Cancer Research and Treatment, University of Torino Medical School, Strada Provinciale 142, 10060 Candiolo, Turin, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Vigna
authors.forename: Mario
authors.initials: M
authors.lastname: Amendola
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Benedicenti
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Simmons
authors.forename: Antonia
authors.initials: A
authors.lastname: Follenzi
authors.forename: Luigi
authors.initials: L
authors.lastname: Naldini
mesh_terms: D000818:Animals; D002460:Cell Line; D005164:Factor IX / Q000235:genetics* / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects*; D005822:Genetic Vectors / Q000235:genetics*; D006801:Humans; D016086:Lentivirus / Q000235:genetics*; D051379:Mice; D016513:Mice, SCID; D008969:Molecular Sequence Data; D009928:Organ Specificity; D015203:Reproducibility of Results; D013752:Tetracycline / Q000494:pharmacology*
chemical_list: D005164:Factor IX; D013752:Tetracycline