Monitoring adenoviral DNA delivery, using a mutant herpes simplex virus type 1 thymidine kinase gene as a PET reporter gene.
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.
Liang
Q
Q
Crump Institute for Molecular Imaging, UCLA School of Medicine, Los Angles, CA, USA.
Nguyen
K
K
Satyamurthy
N
N
Barrio
J R
JR
Phelps
M E
ME
Gambhir
S S
SS
Herschman
H R
HR
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*
D005462:Fluorine Radioisotopes; D019275:Radiopharmaceuticals; D004247:DNA; D013937:Thymidine Kinase