microRNA-34-5p encoded by Spodoptera frugiperda regulates the replication and infection of Autographa californica multiple nucleopolyhedrovirus by targeting odv-e66, ac78 and ie2.

Background: Spodoptera frugiperda is one of the significant migratory pests in the Global Alert issued by the Food and Agriculture Organization of the United Nations. As an insect-specific microbial insecticide, baculovirus has been used to control various pests. MicroRNA-34-5p (miR-34-5p) is involved in regulating growth, reproduction and innate immunity to pathogens in insects, playing an essential role in host-virus interactions. In this study, we explored the critical function of miR-34-5p encoded by S. frugiperda in the anti-Autographa californica multiple nucleopolyhedrovirus (AcMNPV), providing a reference for the design of a miR-34-5p target biopesticide against S. frugiperda and a theoretical basis for the wide application of microRNAs (miRNAs) in green pest control technology.

Results: We focused on miR-34-5p identified as downregulated in Sf9 cells and S. frugiperda larvae infected by AcMNPV. The regulatory function of miR-34-5p in AcMNPV-S. frugiperda interactions was studied by transfecting synthetic mimics and inhibitors, and constructing recombinant bacmids with miR-34-5p overexpression. miR-34-5p inhibited the production of infectious budded virions at the cellular and insect levels, inhibited the replication of the viral DNA and glucose metabolism, and increased the transcription of the antimicrobial peptide gloverin. Furthermore, the virus genes odv-e66, ac78 and ie2 were shown to be direct targets.

Conclusion: We systematically revealed the mechanism by which miR-34-5p is involved in the insect antiviral process. miR-34-5p inhibited the replication and infection of AcMNPV by directly targeting AcMNPV genes, especially ac78 and ie2. Our study provides a new direction and thinking for the prevention and green control of lepidopteran pests. © 2022 Society of Chemical Industry.