A simple technique to enhance the humoral immune response to intracellular protein antigens in genetic immunizations

► DNA vaccines of secreted and intracellular L. chagasi cysteine protease are compared ► N-terminal GM-CSFs were fused to the protease to enable secretion of the chimera ► Anti-protease antisera from immunized mice were evaluated by Western analysis ► Humoral responses were only detected when the protease was intentionally secreted ► The effect was attributed to secretion with no augmentation from GM-CSF activity