title: Lack of an immune response against the tetracycline-dependent transactivator correlates with long-term doxycycline-regulated transgene expression in nonhuman primates after intramuscular injection of recombinant adeno-associated virus.
abstract: We previously documented persistent regulation of erythropoietin (Epo) secretion in mice after a single intramuscular (i.m.) injection of a recombinant adeno-associated virus (rAAV) vector harboring both the tetracycline-dependent transactivator (rtTA) and the Epo cDNA (D. Bohl, A. Salvetti, P. Moullier, and J. M. Heard, Blood 92:1512-1517, 1998). Using the same vector harboring the cynomolgus macaque Epo cDNA instead, the present study evaluated the ability of the tetracycline-regulatable (tetR) system to establish long-term transgene regulation in nonhuman primates. The vector was administered i.m., after which 5-day induction pulses were performed monthly for up to 13 months by using doxycycline (DOX), a tetracycline analog. We show that initial inductions were successful in all individuals and that there was a tight regulation and a rapid deinduction pattern upon DOX withdrawal. For one macaque, regulation of Epo secretion was maintained during the entire experimental period; for the five remaining macaques, secreted Epo became indistinguishable from endogenous Epo upon repeated DOX inductions. We investigated the mechanism involved and showed that, except in the animal in which secretion persisted, delayed humoral and cellular immune responses were directed against the rtTA transactivator protein associated with the reduction of vector DNA in transduced muscles. This study provides some evidence that, when the immune system is not mobilized against the rtTA transactivator, the tetR-regulatable system is able to support long-term transgene regulation in the context of an rAAV in nonhuman primates. In addition, our results suggest potential improvements for vector design.
authors.affiliation: INSERM ERM 0105, Ecole Nationale Vétérinaire, Nantes, France.
authors.forename: David
authors.initials: D
authors.lastname: Favre
authors.forename: Véronique
authors.initials: V
authors.lastname: Blouin
authors.forename: Nathalie
authors.initials: N
authors.lastname: Provost
authors.forename: Radec
authors.initials: R
authors.lastname: Spisek
authors.forename: Françoise
authors.initials: F
authors.lastname: Porrot
authors.forename: Delphine
authors.initials: D
authors.lastname: Bohl
authors.forename: Frederic
authors.initials: F
authors.lastname: Marmé
authors.forename: Yan
authors.initials: Y
authors.lastname: Chérel
authors.forename: Anna
authors.initials: A
authors.lastname: Salvetti
authors.forename: Bruno
authors.initials: B
authors.lastname: Hurtrel
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Heard
authors.forename: Yves
authors.initials: Y
authors.lastname: Rivière
authors.forename: Philippe
authors.initials: P
authors.lastname: Moullier
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000917:Antibody Formation; D018076:DNA, Complementary; D000229:Dependovirus / Q000235:genetics* / Q000276:immunology; D004318:Doxycycline / Q000494:pharmacology; D004921:Erythropoietin / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D005822:Genetic Vectors / Q000008:administration & dosage*; D007111:Immunity, Cellular; D007273:Injections, Intramuscular; D008252:Macaca fascicularis; D011995:Recombination, Genetic; D013752:Tetracycline / Q000378:metabolism / Q000494:pharmacology*; D015534:Trans-Activators / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D019076:Transgenes
chemical_list: D000900:Anti-Bacterial Agents; D018076:DNA, Complementary; D015534:Trans-Activators; D004921:Erythropoietin; D013752:Tetracycline; D004318:Doxycycline