A kind of cytotoxinic gene barnase was cloned downstream of Immediate early promoter from cytomegalovirus (CMV). Recombinant virus vAcCMVBar was constructed using Bac-to-Bac system by insertion of the expression cassette into the polyhedrin gene locus of Autographa californica nuclear polyhedrosis virus (AcNPV). Cytotoxinic effect caused by expression of barnase was observed in four mammalian cells after vAcCMVBar infection Dose-dependent analysis revealed that one of the cells HICAM was the most sensitive to the virus infection. It was. shown that AcNPV could be used as gene transfer vector in mammalian cells and that barnase is the suitable report gene which could be detected more easily than that commonly used.