The fusolin (fus) gene of Choristoneura fumiferana entomopoxvirus was cloned and expressed in insect cells via the baculovirus expression vector system using the polh promoter. A PstI / EcoRI restriction enzyme fragment (1115 bp) which includes the fus gene was cloned into pBlueBac4.5. This engineered plasmid and linearized DNA of Autographa californica nuclear polyhedrosis virus (AcNPV) were cotransfected into Spodoptera frugiperda cells. Selection and purification of high level recombinant baculovirus were performed by polymerase chain reaction and plaque assay. Expression of the fusolin protein (approximately 38 kDa polypeptide) in S. frugiperda cells was determined by SDS-polyacrylamide gel electrophoresis.