Baculovirus-mediated gene transfer systems in silkworm larvae using constitutive host promoters

Abstract

Baculoviruses serve as efficient viral vectors for gene delivery into vertebrate and invertebrate cells. The identification and characterization of the functional promoters in different baculovirus-infected hosts are essential for the efficient gene expression. To establish a baculovirus-mediated gene transfer system in the silkworm, Bombyx mori, we investigated the activities of silkworm-derived TCTP, ACTIN3, and HSC70-4 promoters delivered by AcNPV or BmNPV in various tissues of silkworm. In many of the tested silkworm tissues, the BmHSC70-4 promoter exhibited a higher transcription activity than those of BmTCTP or BmACTIN3 promoters when delivered by AcNPV, which is reported to be incapable of replicating in silkworms. In contrast, the BmACTIN3 promoter was found to be the strongest promoters when delivered by BmNPV. The present results indicate that the BmHSC70-4 promoter is potentially useful for the stable gene expression by the non-replicating AcNPV vector for gene function analysis in the silkworm.