title: Augmentation of transgene-encoded protein after neonatal injection of adeno-associated virus improves hepatic copy number without immune responses.
abstract: BACKGROUND
  Achieving persistent expression is a prerequisite for genetic therapies for inherited metabolic enzymopathies. Such disorders potentially could be treated with gene therapy shortly after birth to prevent pathology. However, rapid cell turnover leads to hepatic episomal vector loss, which diminishes effectiveness. The current studies assessed whether tolerance to transgene proteins expressed in the neonatal period is durable and if the expression may be augmented with subsequent adeno-associated virus (AAV) administration.
  
  
  METHODS
  AAV was administered to mice on day 2 with reinjection at 14 or at 14 and 42 d with examination of changes in hepatic copies and B and T cell-mediated immune responses.
  
  
  RESULTS
  Immune responses to the transgene protein and AAV were absent after neonatal administration. Reinjection at 14 or at 14 and 42 d resulted in augmented expression with greater hepatic genome copies. Unlike controls, immune responses to transgene proteins were not detected in animals injected as neonates and subsequently. However, while no immune response developed after neonatal administration, anticapsid immune responses developed with further injections suggesting immunological ignorance was the initial mechanism of unresponsiveness.
  
  
  CONCLUSIONS
  Persistence of transgene protein allows for tolerance induction permitting readministration of AAV to re-establish protein levels that decline with growth.
authors.affiliation: Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Denise S
authors.initials: DS
authors.lastname: Tai
authors.affiliation: Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Chuhong
authors.initials: C
authors.lastname: Hu
authors.affiliation: Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Elizabeth H
authors.initials: EH
authors.lastname: Kim
authors.affiliation: Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.|Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.|Department of Psychiatry, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.|Department of Urology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.|Intellectual and Developmental Disabilities Research Center at UCLA, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.|Broad Center for Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.|The Semel Institute for Neuroscience, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Gerald S
authors.initials: GS
authors.lastname: Lipshutz
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002213:Capsid; D000229:Dependovirus / Q000235:genetics*; D005260:Female; D018628:Gene Dosage; D005814:Genes, Viral; D015316:Genetic Therapy / Q000379:methods; D005822:Genetic Vectors; D007107:Immune System; D007108:Immune Tolerance; D007111:Immunity, Cellular; D056724:Immunity, Humoral; D007371:Interferon-gamma / Q000378:metabolism; D007376:Interleukin-2 / Q000378:metabolism; D008099:Liver / Q000276:immunology* / Q000378:metabolism / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009929:Organ Size; D013997:Time Factors; D014018:Tissue Distribution; D019076:Transgenes; D014612:Vaccines / Q000235:genetics
chemical_list: D007376:Interleukin-2; D014612:Vaccines; D007371:Interferon-gamma