A baculovirus expression vector derived from the basic protein promoter of Autographa californica nuclear polyhedrosis virus

Hill-Perkins and Possee developed a new baculovirus expression vector using the basic protein promoter from Autographa californica nuclear polyhedrosis virus (AcMNPV). The basic protein is a structural component associated with viral DNA in nucleocapsids and is produced during the late infection phase. The researchers constructed a transfer vector containing the β-galactosidase gene under control of the basic protein promoter, replacing the polyhedrin gene. After cotransfecting Spodoptera frugiperda cells with this transfer vector and infectious AcMNPV DNA, they isolated polyhedrin-negative recombinant viruses expressing high levels of β-galactosidase. Radiolabeling experiments showed β-galactosidase was synthesized between 8 to 24 hours post-infection with peak synthesis at 12 to 15 hours, matching the temporal expression pattern of the native basic protein. This new vector system enables foreign gene expression at earlier infection times than existing polyhedrin-based vectors, potentially advantageous for proteins requiring post-translational modifications and for engineered virus insecticides.

Key findings

• A functional baculovirus expression vector was successfully constructed using the AcMNPV basic protein promoter to drive β-galactosidase expression.
• The basic protein promoter directs foreign gene expression 3-6 hours earlier (peak at 12-15 h post-infection) than the standard polyhedrin promoter (peak at 18 h post-infection).
• Recombinant β-galactosidase accumulated to high levels comparable to native basic protein production in infected cells.
• The temporal regulation of the basic protein promoter was unaffected by its insertion at an alternative genomic position, enabling multi-gene expression systems.