To generate large amounts of a recombinant protein, many investigators have turned to baculovirus expression systems. Compared to bacterial expression systems, the posttranslational processing and folding of recombinant proteins produced in insect cells more closely resembles mammalian processes, and the yields of functional protein are often much greater.
The BacPAK System uses the baculovirus Autographa californica nuclear polyhedrosis virus (AcMNPV) to produce target proteins in insect cells. The target gene is inserted into a shuttle vector, which is cotransfected into insect host cells with the linearized BacPAK6 Viral DNA. The specially designed BacPAK6 Viral DNA forces recombination between the virus and transfer vector, resulting in high recombination efficiency. Following recombination, a few viral plaques are picked and purified, and the recombinant phenotype is verified. The newly isolated recombinant virus can then be amplified and used to infect insect cell cultures to produce large amounts of the desired protein.
If you wish, you can use pBacPAK8-GUS (sold as part of the BacPAK Baculovirus Expression System) as a positive control for the cotransfection step. This transfer vector has the E. coli beta-glucuronidase (GUS) gene cloned downstream of its polyhedrin promoter. Recombination of pBacPAK8-GUS with the BacPAK6 DNA digest generates recombinant viruses that express beta-glucuronidase. Expression of GUS can be detected by generation of a blue color from the chromogenic GUS substrate X-GLUC.