Roles of miR-278-3p in IBP2 regulation and Bombyx mori cytoplasmic polyhedrosis virus replication

•The first report on function of bmo-miRNAs in response to BmCPV infection•IBP2 is a target gene of miR-278-3p in silkworm.•Overexpression of miR-278-3p negatively regulates IBP2 expression in silkworm larvae.•Overexpression of miR-278-3p facilitates BmCPV replication.

Bombyx mori cytoplasmic polyhedrosis virus (BmCPV) is a major viral pathogen of silkworm and remains a big challenge to the sericultural industry. Insulin-related peptide binding protein 2 (IBP2) gene, induced by BmCPV infection may play an important role in B. mori immune response. MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression at the post-transcriptional level and play an important role in various processes, including immunity and antiviral response. In this study, we identified IBP2 as one of the targets for miR-278-3p by using luciferase reporter assay. Overexpression of miR-278-3p negatively regulates the expression of IBP2 in silkworm larvae and positively regulates the mRNA transcript level of BmCPV. Our results suggest that miR-278-3p may play an important role in BmCPV replication. It's the first report on bmo-miRNAs in response to BmCPV infection and could provide a new clue to explore the molecular mechanism of BmCPV infection and host immunity.