DENGUE VIRUS ENVELOPE GLYCOPROTEIN CAN BE SECRETED FROM INSECT CELLS AS A FUSION WITH THE MALTOSE-BINDING PROTEIN

The maltose-binding protein (MalE) contains a signal sequence which al lows its translocation in the periplasm of prokaryotic microorganisms. In this study, MalE was produced in Spodoptera frugiperda (Sf9) lepid opterian cells using the baculovirus expression system. The secretion of MalE, following cleavage of its signal sequence, to the supernatant fluid of recombinant baculovirus-infected Sf9 cells and its affinity for maltodextrin polymers allowed recovery of significant amounts (gre ater than or equal to 10 mu g per 10(6) cells) of highly purified prot ein. The gene encoding the envelope glycoprotein E of the dengue (DEN) type 2 virus deleted of its C-terminal 102 amino acids (D2E Delta 102 ) was fused to the MalE gene. The resulting hybrid MalE-D2E Delta 102 glycoprotein was processed through the Golgi network of Sf9 cells and was secreted. It was retained on a maltodextrin column and was eluted with maltose. Antigenic and immunogenic properties dependent on the th ree-dimensional structure in the native E protein were preserved in th e recombinant MalE-D2E Delta 102 protein. Thus MalE with its signal se quence may be used as a carrier protein for production in the baculovi rus system and purification of proteins which require transportation t hrough intracellular compartments for correct folding and processing.