Production and functional analysis of engineered p
roteins using baculovirus expression system.
Baculovirus expression system is a conventional tool for production of large amounts of engineered protei ns, which may be subsequently purified for further studies in their biological and enzymatic functions. In t his study, two baculovirus expression systems, AcMNPV and BmNPV, were used to produce 3 recombina nt proteins: porcine lactoferrin, phytase of E. coli, and apisimin, which is a small component of royal jelly.
The use of BmNPV expression system is for subsequent massive production of recombinant protein in silk worm, which, after purification, will be added in feeding to increase porcine immunity and alleviate polluti ons caused by porcine feces. We’ve successfully produce recombinant porcine lactoferin, phytase of E. coli , and apisimin of royal jelly by AcMNPV and BmNPV expression systems. Recombinant apisimin protein was further purified for studies for its biological and enzymatic activities. Purified phytase protein produce d by baculovirus expression system exhibited higher enzymatic activity compared to phytase produced by plant. Purified apisimin protein produced by baculovirus expression system did not cause cell toxicity in i mmunological experiment. From ELISA experiment, productions of TNF- , IL-1- and IL-6 increased pro portionally with the concentration of apisimin, indicating activation of immune responses by apisimin. Und er inflammatory condition, e.g., stimulation by LPS, production of TNF- decreased inversely with the con centration of apisimin. On the contrary, productions of IL-1- and IL-6 show initial increase, followed by a steady decline as the concentration of apisimin increased. Therefore, it’s proposed that apisimin could regu late immune response bi-directionally. In test for antibiotic function, apisimin did not suppress bacterial gr owth in 11 bacteria strains tested. However, it exhibited ability in cleaning up free radicals, and this functio n was concentration-dependent.
In conclusion, purified recombinant proteins produced by baculovirus expression system were shown to be
biologically functional. Therefore, baculovirus expression system is a useful tool in studying functions of p
roteins whose functions are still unknown.
