The in vitro effects of CpG oligodeoxynucleotides on the expression of cytokine genes in the common carp (Cyprinus carpio L.) head kidney cells

Synthetic oligodeoxynucleotides with CpG motifs (CpG-ODNs) have gained attention because it elicits strong innate immune responses. CpG-ODNs promote the production of T-helper 1(TH1) and pro-inflammatory cytokines. In fish, knowledge of the effects of CpG-ODNs on the expression of cytokine genes is scarce. In this study, we report that CpG-ODNs induce the expression of pro-inflammatory cytokines in common carp head kidney leucocytes in vitro. Evidence of a TH1 type immune stimulation was observed as the fish homologs of IP-10 (interferon gamma-inducible protein 10; CXCL10) and MCP (monocyte chemotactic protein a CC-chemokine) were induced by CpG. Interleukin 10, a cytokine inhibitory factor, failed to be induced by CpG. These results suggest a robust immune stimulation can be achieved by CpGs and has a potential as an immunostimulant in aquaculture.