title: Persistent expression of hF.IX After tolerance induction by in utero or neonatal administration of AAV-1-F.IX in hemophilia B mice.
abstract: The major complication associated with protein replacement therapy currently used in the treatment of hemophilia B (HB) is the development of antibodies to the infused human Factor IX (hF.IX). We hypothesized that vector-mediated expression of hF.IX, either at a prenatal stage or early in life may lead to tolerance to hF.IX and long-term transgene expression. Fetal, neonatal, and adult F.IX-deficient mice were injected with AAV-1-hF.IX, and the hF.IX levels as well as antibodies to hF.IX in the circulation were assayed. In utero injection followed by postnatal re-administration of adeno-associated virus 1 (AAV-1) vector achieved persistent expression of hF.IX in all animals, with no cellular or humoral immune response to F.IX. Similar results were seen after initial injection in neonatal mice followed by re-administration, whereas all mice injected at the adult stage developed antibodies to hF.IX. In contrast, after administration of AAV-2-hF.IX in the neonatal period, antibodies to hF.IX were formed in all the injected animals. We conclude that in utero or neonatal-stage injection of AAV-1-hF.IX can lead to long-term expression and absence of immune response. The differences in immune response between the AAV-1 and AAV-2 groups suggests that tolerance may be related to differences in bio-distribution, timing of expression, and/or the initial levels of hF.IX expression. This supports the concept of a narrow "window of opportunity" for tolerance induction.
authors.affiliation: Department of Hematology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Denise E
authors.initials: DE
authors.lastname: Sabatino
authors.forename: Tippi C
authors.initials: TC
authors.lastname: Mackenzie
authors.forename: William
authors.initials: W
authors.lastname: Peranteau
authors.forename: Shyrie
authors.initials: S
authors.lastname: Edmonson
authors.forename: Cesare
authors.initials: C
authors.lastname: Campagnoli
authors.forename: Yi-Lin
authors.initials: YL
authors.lastname: Liu
authors.forename: Alan W
authors.initials: AW
authors.lastname: Flake
authors.forename: Katherine A
authors.initials: KA
authors.lastname: High
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002213:Capsid / Q000276:immunology; D000229:Dependovirus / Q000235:genetics; D005164:Factor IX / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000008:administration & dosage / Q000235:genetics*; D002836:Hemophilia B / Q000628:therapy*; D006801:Humans; D007108:Immune Tolerance / Q000276:immunology; D007111:Immunity, Cellular / Q000276:immunology; D008297:Male; D008431:Maternal-Fetal Exchange; D051379:Mice; D009132:Muscles / Q000378:metabolism; D011247:Pregnancy; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism
chemical_list: D005164:Factor IX