SV40 mediates stable gene transfer in vivo

Area of Science:

• Molecular Biology
• Gene Therapy
• Virology

Background:

• Efficient gene transfer in vivo necessitates a nonreplicating vector.
• Simian virus 40 (SV40) has potential as a gene delivery vehicle.

Purpose of the Study:

• To evaluate the efficacy of a recombinant, replication-deficient SV40 vector in transferring gene expression to hematopoietic cells and internal organs in vivo.
• To assess the duration and extent of gene expression mediated by the SV40 vector.

Main Methods:

• A replication-deficient SV40 vector (SVluc) was engineered by replacing the large T antigen gene with firefly luciferase (luc) cDNA under the control of the SV40 early promoter.
• SVluc was administered intravenously to BALB/C mice, and bone marrow cells treated with SVluc were infused into syngeneic hosts.
• Luciferase production was monitored for 105 days using immunochemical analysis and enzyme activity assays in peripheral blood and various organs.

Main Results:

• Sustained luciferase production was observed in 20-25% of peripheral blood nucleated cells from day 20 to day 105.
• Luciferase-producing cells were detected in multiple organs, including liver, spleen, brain, kidney, skin, and colon, for the duration of the study.
• Functionally active luciferase enzyme levels in whole blood remained significantly elevated compared to controls from day 21 to day 105.

Conclusions:

• Replication-deficient SV40 serves as an effective vector for in vivo gene transfer.
• The SV40-based vector facilitates sustained foreign gene expression in hematopoietic stem cells and various internal organs for at least three months.
• SV40 holds promise as a tool for gene therapy applications requiring long-term gene expression.