title: Long-term tracing of adenoviral expression in rat and rabbit using luciferase imaging.
abstract: BACKGROUND
  Luciferase optical imaging provides a novel method to monitor transgene expression in small living animals. As the genetic and immunological heritages of particular animals significantly affect the expression of adenovirus-delivered transgenes, it is essential to know the expression patterns specific to athymic nude and Sprague-Dawley rats, two strains commonly used in rodent models. In this study we set out to determine these patterns. At the same time, we tested luciferase optical imaging in a larger animal, the rabbit.
  
  
  METHODS
  A recombinant luciferase adenoviral vector was injected subcutaneously or intramuscularly into athymic nude rats, Sprague-Dawley rats, and Dutch Belted rabbits. The luciferase expression was assessed using a cooled charge-coupled device.
  
  
  RESULTS
  The luminescent signal was capable of passing through at least 1.3 cm of muscle tissue and proved to be much stronger when luciferin was delivered via a local injection than by an intraperitoneal injection. Although the types of immune cells differed between immunodeficient and immunocompetent rats, similar amounts and patterns of luciferase expression were observed in the musculature in two rat strains during the 1st month after a viral intramuscular injection. The duration of luciferase expression was longer than 15 months in athymic nude rats, 9 months in Sprague-Dawley rats, and 6 months in rabbits following a direct viral injection.
  
  
  CONCLUSIONS
  Luciferase expression after adenoviral gene delivery can persist for longer than 6 months, even in immunocompetent animals. Live imaging of luciferase expression can be performed not only in small animals, but also in larger animals such as rabbits.
authors.affiliation: Department of Neurological Surgery, University of Virginia Health System, Charlottesville, VA 22908, USA. jl9v@virginia.edu
authors.forename: Jin Zhong
authors.initials: JZ
authors.lastname: Li
authors.forename: David
authors.initials: D
authors.lastname: Holman
authors.forename: Hongwei
authors.initials: H
authors.lastname: Li
authors.forename: An-Hsiang
authors.initials: AH
authors.lastname: Liu
authors.forename: Brian
authors.initials: B
authors.lastname: Beres
authors.forename: Gerald R
authors.initials: GR
authors.lastname: Hankins
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Helm
mesh_terms: D000256:Adenoviridae / Q000235:genetics* / Q000378:metabolism*; D017667:Adipocytes / Q000166:cytology / Q000378:metabolism / Q000821:virology; D000818:Animals; D002452:Cell Count; D002478:Cells, Cultured; D003952:Diagnostic Imaging / Q000295:instrumentation / Q000379:methods*; D049454:Firefly Luciferin / Q000378:metabolism; D015870:Gene Expression; D005822:Genetic Vectors / Q000008:administration & dosage; D049409:Luciferases, Firefly / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D008163:Luminescent Measurements; D011817:Rabbits; D051381:Rats; D011923:Rats, Nude; D017207:Rats, Sprague-Dawley; D013045:Species Specificity; D013997:Time Factors; D019076:Transgenes
chemical_list: D049454:Firefly Luciferin; D049409:Luciferases, Firefly