miR-6497-5p suppresses AcMNPV infection by targeting organic cation transport protein in silkworm, Bombyx mori.

Baculovirus is a multipurpose virus with a wide range of applications, such as protein expression, disease therapy, biocontrol, and so forth. It is of great significance to elucidate the mechanisms of their application as biopesticides, since insect resistance to viruses limits their application. Autographa californica nucleopolyhedrovirus (AcMNPV) is a representative species of α-baculovirus, and the silkworm is an ideal model organism for Lepidoptera. Exploring the interactions between the two is an important reference for elucidating the mechanism. In this study, the transcriptome of the silkworm strain p50 hemolymph was examined after 36 h of AcMNPV infection, and the data obtained were assembled and annotated with messenger RNA and microRNA (miRNA), respectively. Three miRNAs related to AcMNPV infection were obtained, including miR-6497-5p, miR-6498-3p, and miR-6498-5p. Among them, miR-6497-5p was a key miRNA for AcMNPV inhibition, and its downstream target gene, organic cation transporter protein (BmOctp), was also confirmed. Furthermore, knockdown and overexpression of BmOctp revealed that it was beneficial for viral infection, and this function was found as early as 6 h after virus infection, which may be related to the early transmembrane transport of the virus. This study is the first screening of miRNAs related to AcMNPV in silkworms, and the results provide important theoretical references for elucidating the mechanism of baculovirus-host and its potential applications.