Reducing mobilization of simian immunodeficiency virus based vectors by primer complementation.

Area of Science:

• * Gene Therapy Vector Safety
• * Lentiviral Vector Biology
• * Virology

Background:

• * Primate lentiviral vectors pose a risk of mobilization by human immunodeficiency viruses (HIV).
• * HIV infection of transduced cells can lead to vector RNA packaging and transfer.
• * Vector mobilization by HIV is a critical safety concern in gene therapy.

Purpose of the Study:

• * To develop a novel strategy to minimize lentiviral vector mobilization by HIV.
• * To assess the efficacy of primer complementation in preventing vector mobilization.
• * To improve the safety profile of simian immunodeficiency virus (SIV)-based gene therapy vectors.

Main Methods:

• * A primer complementation strategy was developed by mutating the primer binding site (PBS) of an SIV-based vector.
• * The mutated PBS abolished tRNA primer binding, blocking reverse transcription.
• * An artificial tRNA was provided during vector production to bypass the block, achieving high titers.

Main Results:

• * Primer-complemented SIV vectors showed >150-fold less mobilization by HIV-1 compared to wild-type vectors.
• * Mobilization by homologous SIV was less inhibited, indicating reduced efficacy against SIV.
• * Combining primer complementation with self-inactivating vectors rendered vector mobilization undetectable.

Conclusions:

• * Primer complementation significantly reduces the risk of SIV-based vector mobilization by HIV-1.
• * This approach enhances the safety of gene therapy vectors.
• * Combining strategies offers the most robust protection against vector mobilization.