Simultaneous synthesis of enzymatically active luciferase and biologically active β subunit of human chorionic gonadotropin in caterpillars infected with a recombinant baculovirus

The β subunit of human chorionic gonadotropin (βhCG), a secretory and extensively glycosylated hormone, and firefly luciferase, a non-secretory enzyme, were simultaneously synthesized in Spodoptera larvae upon infection with a dual expression recombinant baculovirus, vAcβhCG-luc. Luciferase was retained predominantly in the body tissue while βhCG was secreted into the hemolymph of infected larvae. Both the proteins were similar to their authentic counterparts in terms of immunoreactivity and bioactivity. The caterpillar-derived recombinant hCG exhibited reduced electrophoretic mobility on SDS-PAGE and increased biological activity as compared to the hCG expressed in insect cells in culture. The implications of using the larval system for expressing an extensively glycosylated protein are discusced