Expression of Human Bone Morphogenetic Protein 2 in Bombyx mori Larvae and Its Purification

Recombinant Bm-BacPAK-BMP2 virus which contains the human bone morphogenetic protein 2 (BMP2) cDNA gene under the control of polyhedrin gene promoter was generated by cotransfection into Bm-N cells with the transfer plasmid pBacPAK-BMP2 and the modified Bombyx mori nuclear polyhedrosis virus Bm-BacPAK genomic DNA. On the fifth day after infection with the recombinant virus, Bombyx mori larvae produced about 10 &mgr;g rBMP2 in 1 ml hemolymph. The expressed rBMP2 was processed into 16 kD C-terminal fragments and formed 30 kD dimmers with disulfide bonds in vivo. The protein was purified to about 90% purity and induced cartilage locally in rats 7 days after subcutaneous transplantation.