[Show abstract][Hide abstract] ABSTRACT: The kinetics of gene expression from adenovirus-based delivery vectors will be an important variable influencing the efficacy and toxicity of these vectors. As different promoters have variable strengths and kinetic profiles, the optimal dose of a therapeutic transgene product over time may be achieved by varying the promoter.
We analyzed several viral and cellular promoters in the context of adenovector gene delivery in the mouse. The kinetics of transgene expression was evaluated following intramuscular and intravenous delivery.
Transgene expression from the cytomegalovirus (CMV) promoter was rapidly down-regulated in the tissues following intravenous administration of adenovectors. In contrast, transgene expression from the Rous sarcoma virus (RSV) promoter increased over time such that, at 3 weeks, expression was 10-fold higher than that from the CMV promoter-containing vector in all tissues. The kinetics of transgene expression from these vectors was similar when they were delivered via the intramuscular route in BALB/c, C57BL/6 and immunodeficient mice. Efficient repeat administration of an adenovirus vector, in the presence of neutralizing antibodies, was achieved in the skeletal muscle and transgene expression persisted with the same kinetics as in naïve animals.
These results demonstrate that the in vivo kinetics of transgene expression by adenovectors is greatly influenced by the promoter. Adenovectors can be designed to deliver a transient bolus or a sustained level of protein expression in the target tissue depending on the requirements for particular indications. These results have implications for both therapeutic and vaccine indications.
Full-text · Article · Feb 2008 · The Journal of Gene Medicine
[Show abstract][Hide abstract] ABSTRACT: Adenovirus vectors expressing gene products that can induce apoptosis have potential utility in gene therapy applications ranging from the treatment of proliferative diseases to transplantation. However, adenovirus vectors carrying proapoptotic gene products are difficult to produce, as the apoptotic environment is not conducive to adenovirus gene expression and replication. Production of AdFasL/G, an adenovirus vector that expresses high levels of Fas ligand, was severely reduced in the 293 packaging cell line. Increased yields of AdFasL/G were achieved by inclusion of peptide-based caspase inhibitors in the growth medium. However, use of these inhibitors for large-scale production would be difficult and expensive. A screen for gene products that increase the yield of AdFasL/G in 293 cells revealed that the poxvirus serpin CrmA and the adenovirus 14.7K product were able to increase virus yields significantly. Apoptosis induced by AdFasL/G was attenuated in 293CrmA cell lines and virus titers were increased dramatically. However, serial passage of AdFasL/G on 293CrmA cells resulted in the generation of replication-competent adenovirus. To resolve this problem, the CrmA gene was introduced into AE25 cells, an E1-complementing cell line that has limited sequence identity with the vectors. AdFasL/G titers were increased 100-fold on AE25CrmA cells relative to the AE25 cells and RCA contamination was not detectable. In addition, adenovirus vectors that express FADD, caspase 8, and Fas/APO1 were produced efficiently in AE25CrmA and 293CrmA.
Full-text · Article · Feb 2000 · Human Gene Therapy