Self-inactivating lentiviral vectors with U3 and U5 modifications

Area of Science:

• Molecular Biology
• Virology
• Gene Therapy

Background:

• Lentiviral vectors are crucial for gene therapy due to their ability to integrate into host-cell genomes, including non-dividing cells.
• A safe and efficient lentiviral vector system is essential for clinical applications.
• Previous work established a human immunodeficiency virus type 1 (HIV-1)-derived three-plasmid lentiviral vector system (pHP, pTV, pHEF-VSVG).

Purpose of the Study:

• To enhance the safety and efficiency of lentiviral vectors for clinical applications.
• To modify the long terminal repeats (LTRs) of the pTV transducing vector.
• To generate a self-inactivating (SIN) lentiviral vector with improved performance.

Main Methods:

• Modified the 5' U3 region of the LTR by replacing it with a truncated cytomegalovirus (CMV) immediate early (IE) enhancer/TATA promoter.
• Deleted the 3' U3 region of the LTR, retaining the integration attachment site.
• Replaced the 3' U5 region with the bovine growth hormone polyadenylation (bGHpA) sequence to restore vector function.

Main Results:

• The modified vector (pTV) exhibited a self-inactivating (SIN) phenotype after transduction.
• Transduction efficiencies for dividing and non-dividing cells were similar.
• Vector titers were twice as high as the wild-type construct, with 80% of wild-type efficiency initially.
• Further deletion of 5' U5 impaired vector efficiency, indicating its critical role.

Conclusions:

• LTR modifications significantly improved both the safety and efficacy of the HP/TV lentiviral vector system.
• The SIN lentiviral vector demonstrates robust transduction of both dividing and non-dividing cells.
• These optimized lentiviral vectors represent a safer and more effective tool for gene therapy.