Tetracycline-regulated gene expression in replication-incompetent herpes simplex virus vectors

Area of Science:

• Molecular Biology
• Gene Therapy
• Virology

Background:

• Herpes simplex virus (HSV) vectors show promise for gene delivery but lack precise foreign gene expression control.
• The tetracycline-inducible gene expression system offers robust regulation and is widely utilized.

Purpose of the Study:

• To adapt the tetracycline-inducible system for use in replication-incompetent HSV vectors.
• To develop HSV vectors with regulated foreign gene expression for enhanced gene therapy applications.

Main Methods:

• Constructed HSV vectors with Tet-inducible promoters (minimal CMV, minimal ICP0, truncated ICP0) linked to a tetracycline response element (TRE).
• Introduced vectors into cell lines expressing Tet transactivators to assess lacZ gene expression.
• Engineered vectors to coexpress inducible Tet transactivators for broader cell-type applicability.
• Developed vectors with modified Tet transactivators to improve induction properties.

Main Results:

• All engineered promoter constructs demonstrated doxycycline-regulated expression of the lacZ marker gene.
• ICP0 promoter constructs yielded higher and more sustained lacZ expression compared to the CMV construct.
• The CMV promoter construct exhibited the highest relative induction level.
• Coexpression of Tet transactivators enabled inducible gene expression in diverse cell types, including differentiated NT2 neurons.
• Modified Tet transactivators enhanced induction properties, showcasing system flexibility.

Conclusions:

• The tetracycline-inducible system is effectively adapted for regulating foreign gene expression in replication-incompetent HSV vectors.
• Different promoter strategies (ICP0 vs. CMV) offer distinct advantages for specific gene therapy applications.
• Self-contained Tet-regulated HSV vectors provide versatile and controllable gene expression across various cell types.