Inducible gene expression from vaccinia virus vectors

Area of Science:

• Molecular Biology
• Virology
• Gene Expression Systems

Background:

• Controlling gene expression in vaccinia virus (VV) recombinants is crucial for functional studies.
• Existing methods may lack precise temporal or quantitative control.

Purpose of the Study:

• To develop and characterize an inducible gene expression system for VV vectors.
• To utilize the Escherichia coli lac repressor/operator system for inducible gene expression in VV.
• To demonstrate the utility of this system for analyzing VV gene function.

Main Methods:

• Constructed VV recombinants expressing the lac I repressor protein.
• Engineered VV recombinants with synthetic lac operator sequences linked to a reporter gene (luciferase).
• Assessed gene expression levels and inducibility using luciferase assays and S1 nuclease protection.

Main Results:

• The lac I repressor/operator system effectively controlled luciferase expression transcriptionally.
• Inducible inhibition of gene expression ranged from 30% to over 99.9% depending on operator number and position.
• Isopropyl β-D-1-thiogalactopyranoside (IPTG) addition restored enzyme activity, demonstrating inducibility.
• The system was functional and stable in VV genome, enabling controlled expression of a viral gene and analysis of its phenotype.

Conclusions:

• A robust, inducible gene expression system based on the lac I repressor/operator has been established for VV vectors.
• This system provides a powerful tool for the functional analysis of viral genes and their associated phenotypes.
• The developed plasmid vectors offer broad applicability for inducible gene expression in VV recombinants.