MiR-192 and miR-731 synergically inhibit RGNNV infection by targeting ULK1-mediated autophagy in sea perch (Lateolabrax japonicus)

MicroRNAs (miRNAs) are crucial regulators of gene expression and are closely linked to viral infections. Nervous necrosis virus (NNV) poses a significant threat to global fish aquaculture. This study investigates the roles of miR-192 and miR-731 in controlling NNV infection and associated autophagy in sea perch (Lateolabrax japonicus). Our findings reveal that both miRNAs are upregulated in infected brain tissues and cells of sea perch, leading to reduced NNV replication. miR-192 and miR-731 synergistically reduce NNV replication by downregulating the RNA-dependent RNA polymerase and capsid protein genes, and disrupting autophagy by altering LC3 distribution and autophagy-related protein expressions. Additionally, L. japonicus unc-51 like autophagy activating kinase 1 protein (LjULK1) was identified as the target of miR-192 and miR-731. LjULK1 is integrally associated to the ULK-VAPs-Atg13 autophagic signaling, enhancing NNV-induced autophagy, and facilitating viral infection. Modulating LjULK1 expression counteracts the inhibitory effects of miR-192 and miR-731 on NNV, suggesting these miRNAs act as negative regulators of NNV infection by targeting LjULK1-mediated autophagy. Our findings reveal a novel miRNAs-regulated antiviral mechanism against NNV, offering insights into potential strategy to prevent NNV infection in fish.