title: Regulatable gutless adenovirus vectors sustain inducible transgene expression in the brain in the presence of an immune response against adenoviruses.
abstract: In view of recent serious adverse events and advances in gene therapy technologies, the use of regulatable expression systems is becoming recognized as indispensable adjuncts to successful clinical gene therapy. In the present work we optimized high-capacity adenoviral (HC-Ad) vectors encoding the novel tetracycline-dependent (TetOn)-regulatory elements for efficient and regulatable gene expression in the rat brain in vivo. We constructed two HC-Ad vectors encoding beta-galactosidase (beta-gal) driven by a TetOn system containing the rtTAS(s)M2 transactivator and the tTS(Kid) repressor under the control of the murine cytomegalovirus (mCMV) (HC-Ad-mTetON-beta-Gal) or the human CMV (hCMV) promoter (HC-Ad-hTetON-beta-Gal). Expression was tightly regulatable by doxycycline (Dox), reaching maximum expression in vivo at 6 days and returning to basal levels at 10 days following the addition or removal of Dox, respectively. Both vectors achieved higher transgene expression levels compared to the expression from vectors encoding the constitutive mCMV or hCMV promoter. HC-Ad-mTetON-beta-Gal yielded the highest transgene expression levels and expressed in both neurons and astrocytes. Antivector immune responses continue to limit the clinical use of vectors. We thus tested the inducibility and longevity of HC-Ad-mediated transgene expression in the brain of rats immunized against adenovirus by prior intradermal injections of RAds. Regulated transgene expression from HC-Ad-mTetON-beta-Gal remained active even in the presence of a significant systemic immune response. Therefore, these vectors display two coveted characteristics of clinically useful vectors, namely their regulation and effectiveness even in the presence of prior immunization against adenovirus.
authors.affiliation: Gene Therapeutics Research Institute, Cedars-Sinai Medical Center, 8700 Beverly Blvd., Davis Building, Research Pavilion, Room 5090, Los Angeles, CA 90048, USA.
authors.forename: Weidong
authors.initials: W
authors.lastname: Xiong
authors.forename: Shyam
authors.initials: S
authors.lastname: Goverdhana
authors.forename: Sandra A
authors.initials: SA
authors.lastname: Sciascia
authors.forename: Marianela
authors.initials: M
authors.lastname: Candolfi
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Zirger
authors.forename: Carlos
authors.initials: C
authors.lastname: Barcia
authors.forename: James F
authors.initials: JF
authors.lastname: Curtin
authors.forename: Gwendalyn D
authors.initials: GD
authors.lastname: King
authors.forename: Gabriela
authors.initials: G
authors.lastname: Jaita
authors.forename: Chunyan
authors.initials: C
authors.lastname: Liu
authors.forename: Kurt
authors.initials: K
authors.lastname: Kroeger
authors.forename: Hasmik
authors.initials: H
authors.lastname: Agadjanian
authors.forename: Lali
authors.initials: L
authors.lastname: Medina-Kauwe
authors.forename: Donna
authors.initials: D
authors.lastname: Palmer
authors.forename: Philip
authors.initials: P
authors.lastname: Ng
authors.forename: Pedro R
authors.initials: PR
authors.lastname: Lowenstein
authors.forename: Maria G
authors.initials: MG
authors.lastname: Castro
mesh_terms: D000260:Adenoviruses, Human / Q000235:genetics / Q000502:physiology*; D000818:Animals; D000956:Antigens, Viral / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D005822:Genetic Vectors; D006801:Humans; D051381:Rats; D013752:Tetracycline / Q000494:pharmacology*; D019076:Transgenes / Q000187:drug effects / Q000502:physiology*; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics
chemical_list: D000956:Antigens, Viral; D001616:beta-Galactosidase; D013752:Tetracycline