title: Genetic incorporation of human metallothionein into the adenovirus protein IX for non-invasive SPECT imaging.
abstract: As the limits of existing treatments for cancer are recognized, clearly novel therapies must be considered for successful treatment; cancer therapy using adenovirus vectors is a promising strategy. However tracking the biodistribution of adenovirus vectors in vivo is limited to invasive procedures such as biopsies, which are error prone, non-quantitative, and do not give a full representation of the pharmacokinetics involved. Current non-invasive imaging strategies using reporter gene expression have been applied to analyze adenoviral vectors. The major drawback to approaches that tag viruses with reporter genes is that these systems require initial viral infection and subsequent cellular expression of a reporter gene to allow non-invasive imaging. As an alternative to conventional vector detection techniques, we developed a specific genetic labeling system whereby an adenoviral vector incorporates a fusion between capsid protein IX and human metallothionein. Our study herein clearly demonstrates our ability to rescue viable adenoviral particles that display functional metallothionein (MT) as a component of their capsid surface. We demonstrate the feasibility of (99m)Tc binding in vitro to the pIX-MT fusion on the capsid of adenovirus virions using a simple transchelation reaction. SPECT imaging of a mouse after administration of a (99m)Tc-radiolabeled virus showed clear localization of radioactivity to the liver. This result strongly supports imaging using pIX-MT, visualizing the normal biodistribution of Ad primarily to the liver upon injection into mice. The ability we have developed to view real-time biodistribution in their physiological milieu represents a significant tool to study adenovirus biology in vivo.
authors.affiliation: Gene Therapy Program, Department of Cellular Biology, LSU Health Sciences Center, Shreveport, Louisiana, United States of America. jmathi@lsuhsc.edu
authors.forename: J Michael
authors.initials: JM
authors.lastname: Mathis
authors.forename: Shilpa
authors.initials: S
authors.lastname: Bhatia
authors.forename: Alok
authors.initials: A
authors.lastname: Khandelwal
authors.forename: Imre
authors.initials: I
authors.lastname: Kovesdi
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Lokitz
authors.forename: Yoshi
authors.initials: Y
authors.lastname: Odaka
authors.forename: Amol M
authors.initials: AM
authors.lastname: Takalkar
authors.forename: Tracee
authors.initials: T
authors.lastname: Terry
authors.forename: David T
authors.initials: DT
authors.lastname: Curiel
mesh_terms: D000256:Adenoviridae / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D000818:Animals; D019677:Artificial Gene Fusion / Q000379:methods*; D001667:Binding, Competitive; D036022:Capsid Proteins / Q000235:genetics*; D004261:DNA Replication; D004279:DNA, Viral / Q000096:biosynthesis; D005260:Female; D005822:Genetic Vectors / Q000235:genetics; D057809:HEK293 Cells; D006801:Humans; D008668:Metallothionein / Q000235:genetics*; D008670:Metals / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D015609:Organotechnetium Compounds / Q000378:metabolism; D055550:Protein Stability; D015899:Tomography, Emission-Computed, Single-Photon; D014771:Virion / Q000235:genetics / Q000378:metabolism / Q000502:physiology
chemical_list: D036022:Capsid Proteins; D004279:DNA, Viral; D008670:Metals; D015609:Organotechnetium Compounds; D008668:Metallothionein