A BACULOVIRUS-EXPRESSED FUSION PROTEIN CONTAINING THE ANTIBODY-BINDING DOMAIN OF PROTEIN-A AND INSECT LUCIFERASE

A fusion construct encoding two antibody-binding sites of protein A fr om Staphylococcus aureus and click beetle, Pyrophorus plagiophthalamus , luciferase (LucGR) was designed and expressed using the baculovirus system. The construct was inserted under the transcriptional regulatio n of the polyhedrin gene promoter of the Autographa californica nuclea r polyhedrosis virus (AcNPV) and expressed in the insect Spodoperta fr ugiperda cell line during viral infection. The properties of the resul tant chimeric protein product, protA-LucGR, were studied both in vivo and in vitro by using i) luminometry, ii) immunoblot analysis, iii) im munoprecipitation, iv) metabolic labeling procedures and v) luminescen t immunoassays. Together, the results clearly demonstrate that the lig ht-emitting properties of the fused luciferase construct remain intact . Further, the antibody-binding domain of protein A retains its activi ty as it binds to both rabbit and goat as well as human immunoglobulin s. Due to the dual biological function of this fusion protein, it shou ld provide a potential reagent within the field of molecular biology a nd diagnostics.