MiR-130c-5p targets the SHVV gene and upregulates immune cytokines (IL-6, IL-22, IL-1β) to inhibit viral replication.

Background: (SHVV) has led to huge economic losses in snakehead aquaculture, and its pathogenic mechanisms is still not fully understood. MicroRNAs (miRNAs), as an important class of non-coding RNAs, play a key regulatory role in the process of viral infection.

Methods: We examined the effect of SHVV infection on the expression of miR-130c-5p and the effect of overexpression of miR-130c-5p on the proliferation of SHVV. Cotransfection of viral N protein and miR-130c-5p, and the effect of miR-130c-5p on the expression of N protein was detected. Meanwhile, the effect of overexpression of miR-130c-5p on the expression of various immune factors in the case of viral infection were also tested.

Results: In this study, SHVV infection significantly upregulated the expression of miR-130c-5p in channel catfish ovary (CCO) cells in a time- and dose-dependent manner. The further research revealed that miR-130c-5p mimic significantly inhibited, while its inhibitors promoted SHVV replication. In addition, miR-130c-5p could directly target the viral mRNA of gene, and overexpression of miR-130c-5p could significantly decrease, and conversely, downregulation of miR-130c-5p could increase the mRNA and protein expression of the viral n gene. Meanwhile, overexpression of miR-130c-5p also upregulated the expression of immune-related genes, such as nucleotide-oligomerization domain (NOD)-like receptor subfamily C3 (NLRC3), myeloid differentiation factor 88 (MyD88), nuclear factor kappa-B (NF-κB), interleukin-6 (IL-6), interleukin-22 (IL-22), and interleukin-1beta (IL-1β) in host cells.

Conclusion: miR-130c-5p was upregulated in the host during SHVV infection, and the upregulated miR-130c-5p directly inhibited viral replication by targeting the gene of SHVV and promoting viral nucleoprotein degradation. The up-regulated miR-130c-5p also activated the expression of immune-related genes such as NLRC3, MyD88, NF-κB, IL-6, IL-22, and IL-1β, which were involved in the regulation of the signaling pathways including NF-κB, MyD88, Toll-like receptor (TLR), NLR, and janus tyrosine kinase-signal converter and activator of transcription (JAK-STAT), to enhance the host's antiviral immune response, and thus indirectly inhibited the viral proliferation.