Bovine respiratory syncytial virus nucleocapsid protein expressed in insect cells specifically interacts with the phosphoprotein and the M2 protein.

The coding region of the gene for the nucleocapsid (N) protein of bovine respiratory syncytial virus has been inserted into the genome of Autographa californica nuclear polyhedrosis virus (AcNPV) using transfer vector pVL 1393. Infection of Spodoptera frugiperda cells with recombinant virus resulted in the synthesis of high levels of N protein. This protein was indistinguishable from the authentic bovine respiratory syncytial virus (BRSV) N protein by SDS-gel electrophoresis and immunoprecipitation with anti-BRSV serum. [35S]methionine-labeled N protein synthesized in S. frugiperda cells was used in a protein-blotting protein overlay assay for its interactions with BRSV-infected cell proteins. The N protein synthesized in S. frugiperda cells was found to specifically interact with the phosphoprotein (P) and M2 protein of BRSV but only with the P protein of human RSV. Our results suggest that the recombinant N protein produced in S. frugiperda cells could be used to determine the domains on N protein required for binding to P and M2 proteins.