Downregulated miR-15b-5p induces suppressor of cytokine signaling 6 (SOCS6) expression during viral hemorrhagic septicemia virus infection in olive flounder (Paralichthys olivaceus)

MicroRNAs (miRNAs) are endogenous small non-coding RNAs consisted of 21–25 nucleotides that modulate the gene expression by binding to 3′ untranslated region (3′ UTR) of target messenger RNA (mRNA) at the post-transcriptional level. The miRNAs are well known to participate in various physiological processes including cellular differentiation, apoptosis, angiogenesis and immune responses. In particular, during a viral infection, the virus regulates host miRNA expression to evade host immunity. In this study, we investigated whether viral hemorrhagic septicemia virus (VHSV) infection affects the expression of miR-15b-5p and its target gene, suppressor of cytokine signaling (SOCS6) in olive flounder (Paralichthys olivaceus). The relative expression of miR-15b-5p and SOCS6 was analyzed in VHSV-infected olive flounder at different time points: 1, 3, and 7 days post infection (dpi). The expression of miR-15b-5p was decreased in the infected group but that of SOCS6 was increased. These alterations in miR-15b-5p and SOCS6 expression suggest that they could be important factors regulated by VHSV during infection.