Modification of human immunodeficiency virus type 1 reverse transcriptase to target cells with elevated cellular dNTP...

Area of Science:

• Virology
• Molecular Biology
• Cancer Biology

Background:

• Viruses rely on cellular deoxynucleoside triphosphates (dNTPs) for replication, but dNTP availability varies significantly between cell types.
• This variation is due to cell cycle-dependent dNTP biosynthesis, leading to differences between normal and tumor cells.

Purpose of the Study:

• To investigate if modifying viral DNA polymerase dNTP utilization and binding affinity can confer cell-type specificity.
• To determine if viral vectors can be engineered to target cells with specific dNTP concentrations.

Main Methods:

• Utilized a mutant HIV-1 reverse transcriptase (RT) (Q151N) with reduced dNTP binding affinity, active only at high dNTP concentrations.
• Compared transduction efficiency of wild-type and Q151N mutant HIV-1 vectors in primary cells (HLFs, keratinocytes) versus tumor cells.
• Assessed the effect of deoxynucleoside pretreatment on HLF transduction by the mutant vector.
• Evaluated the therapeutic potential by expressing herpes simplex virus-thymidine kinase in tumor cells.

Main Results:

• The Q151N mutant HIV-1 vector preferentially transduced tumor cells with higher dNTP levels compared to primary cells.
• The mutant vector failed to transduce HLFs and keratinocytes but efficiently transduced tumor cells.
• Increasing cellular dNTPs in HLFs via deoxynucleoside pretreatment enabled transduction by the mutant vector.
• The Q151N vector conferred ganciclovir sensitivity to tumor cells expressing HSV-TK.

Conclusions:

• Viral DNA polymerase modification can switch viral infection specificity based on cellular dNTP concentrations.
• Elevated dNTP levels in tumor cells can be exploited as a specific host factor for targeted gene delivery.
• This approach offers a novel strategy for tumor-specific gene therapy and drug delivery.