Molecular cloning and expression analysis of interleukin-1β and interleukin-1 receptor type I genes in yellow catfish (Pelteobagrus fulvidraco): Responses to challenge of Edwardsiella ictaluri.

Interleukin-1β (IL-1β) is one of the pivotal early pro-inflammatory cytokines, which play important roles in regulating immune response and inducing a series of inflammatory reactions to infections. Interleukin-1 type I receptor (IL-1RI) is a receptor of the IL-1β that can mediate IL-1-dependent activation. In this study, partial cDNA sequences of the Pf_IL-1β and Pf_IL-1RI genes were cloned from yellow catfish (Pelteobagrus fulvidraco). The open reading frames (ORF) of Pf_IL-1β and Pf_IL-1RI genes encode putative peptides of 280 and 543 amino acids, respectively. The deduced amino acid sequences of these two genes shared highly conserved structures with those from other teleosts. Quantitative real-time PCR results showed that the Pf_IL-1β mRNA had relatively high expression levels in trunk kidney and blood, and the Pf_IL-1RI mRNA was highly expressed in blood and had relatively high expression level in liver. Ontogenetic expression analyses indicate that the Pf_IL-1β and Pf_IL-1RI genes may play important roles during the embryonic developmental stages. The mRNA expression levels of Pf_IL-1β and Pf_IL-1RI genes were up-regulated in the trunk kidney, head kidney, blood, spleen, heart and liver after Edwardsiella ictaluri challenge. Western blot analyses showed that Pf_IL-1β protein was highly expressed in the spleen and head kidney, but not in the fin of adult individuals. These results suggest that the Pf_IL-1β and Pf_IL-1RI genes may play significant roles in the immune regulation and defense against E. ictaluri in the yellow catfish.