Facile monitoring of baculovirus infection for foreign protein expression under very late polyhedrin promoter using green fluorescent protein reporter under early-to-late promoter

A recombinant baculovirus derived from the Autographa californica nuclear polyhedrosis virus (AcNPV) was constructed so that the green fluorescent protein (GFP) was produced via the early-to-late (ETL) promoter. This enabled rapid monitoring of the infection of Sf-9 insect cells. Notably, GFP and its fluorescence appeared ∼18 h prior to proteins expressed using very late polyhedrin (Polh) promoter. It is anticipated that the use of GFP under the control of ETL promoter will facilitate vector construction, virus isolation, and titer determination.