Enhanced production of secretory β1,3-N-acetylglucosaminyltransferase 2 fusion protein into hemolymph of Bombyx mori larvae using recombinant BmNPV bacmid integrated signal sequence

The enhanced secretion of β1,3-N-acetylglucosaminyltransferase 2 (β3GnT2) fusion protein into the hemolymph of Bombyx mori larvae was studied using a recombinant B. mori nucleopolyhedrovirus (BmNPV) bacmid integrating seven signal sequences. When the BmNPV bacmid encoding the signal sequences from the silkworm B. mori bombyxin (bx) and B. mori prophenoloxidase-activating enzyme (ppae) was injected into silkworm larvae, 56.1 and 51.5 mU/ml β3GnT, respectively, were secreted into the hemolymph of silkworm larvae. For bx, 97.3% of the total β3GnT activity was secreted into hemolymph, and only 1.1% remained in the intestines of silkworm larvae. For ppae, 90.8% of the total β3GnT activity was secreted to the hemolymph, but 7.8% remained in the intestines of silkworm larvae. Using the BmNPV bacmid encoding bx, the amount of secreted β3GnT was 91 μg per larva, which was 2.5% of the total amount of protein in the hemolymph.