title: Monitoring adenoviral DNA delivery, using a mutant herpes simplex virus type 1 thymidine kinase gene as a PET reporter gene.
abstract: Current gene therapy protocols often suffer from an inability to monitor the site, level and persistence of gene expression following somatic DNA delivery. Herpes simplex virus 1 thymidine kinase (HSV1-tk) is currently under intensive investigation as a reporter gene for in vivo imaging of reporter gene expression. The presence of the HSV1-tk reporter gene is repetitively and non-invasively monitored by systemic injection of positron-emitting, radionuclide-labeled thymidine analogues or acycloguanosine HSV1-TK substrates and subsequent detection, by positron emission tomography, of trapped, phosphorylated product. To improve the efficacy of the HSV1-tk PET reporter gene system, both alternative substrates and mutations in the HSV1-tk gene have been described. We used a replication defective adenovirus to deliver the HSV1-sr39tk mutant enzyme and the wild-type HSV1-tk enzyme to mice. HSV1-sr39TK demonstrates greater sensitivity than wild-type HSV1-TK enzyme in vivo, using 9-[(4-[(18)F]fluoro-3-hydroxymethylbutyl)guanine as probe, following adenovirus-mediated hepatic expression in mice. Using this adenoviral delivery system, the location, magnitude and duration of HSV1-sr39tk PET reporter gene expression could be non-invasively, quantitatively and repetitively monitored for over 3 months by microPET.
authors.affiliation: Crump Institute for Molecular Imaging, UCLA School of Medicine, Los Angles, CA, USA.
authors.forename: Q
authors.initials: Q
authors.lastname: Liang
authors.forename: K
authors.initials: K
authors.lastname: Nguyen
authors.forename: N
authors.initials: N
authors.lastname: Satyamurthy
authors.forename: J R
authors.initials: JR
authors.lastname: Barrio
authors.forename: M E
authors.initials: ME
authors.lastname: Phelps
authors.forename: S S
authors.initials: SS
authors.lastname: Gambhir
authors.forename: H R
authors.initials: HR
authors.lastname: Herschman
mesh_terms: D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D002460:Cell Line; D004247:DNA / Q000008:administration & dosage*; D005462:Fluorine Radioisotopes; D015870:Gene Expression; D017930:Genes, Reporter; D005822:Genetic Vectors / Q000008:administration & dosage; D018259:Herpesvirus 1, Human / Q000201:enzymology*; D008099:Liver / Q000000981:diagnostic imaging; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009154:Mutation; D019275:Radiopharmaceuticals; D013937:Thymidine Kinase / Q000032:analysis / Q000235:genetics*; D014055:Tomography, Emission-Computed / Q000379:methods*
chemical_list: D005462:Fluorine Radioisotopes; D019275:Radiopharmaceuticals; D004247:DNA; D013937:Thymidine Kinase