Green fluorescent protein as a tool for screening recombinant baculoviruses.

The gene encoding the green fluorescent protein (GFP) from the jellyfish Aequorea victoria, ligated to the honeybee melittin signal peptide-encoding sequence, was inserted under transcriptional control of the polyhedrin promoter of the Autographa californica nuclear polyhedrosis virus and expressed in the Spodoptera frugiperda insect cell line Sf9 during viral infection. The recombinant green fluorescent protein was identified by SDS-PAGE gel electrophoresis followed by Coomassie blue staining of lysates from the recombinant baculovirus infected insect cells. Emission and excitation scanning of the recombinant baculovirus infected insect cells gave an emission maximum of 509 nm and excitation maximum of 398 nm. The GFP protein expressed was also detected in infected insect cells by a flow cytometer analysis.