Abstract

CD27 is a member of tumor necrosis factor receptor superfamily, and plays a central role in B cell-mediated immune response in mammals. However, the functional characterization of CD27 molecule remains unclear in bony fish. In this study, the CD27 molecule of Nile tilapia (OnCD27) was cloned and its functional characterization was identified by pursuing the expression patterns in T cell-dependent (TD) response and B cell differentiation process. The open reading frame (ORF) of OnCD27 is 666 bp of the nucleotide sequence, encoding a protein of 221 amino acid including two TNFR domains in the extracellular region. Bioinformatics analysis indicated that OnCD27 was highly homologous to other bony fish and similar to mammals. Tissue distribution analysis displayed that the relative expression of OnCD27 was highest in spleen among the examined tissues. The OnCD27 expression was significantly up-regulated in spleen and head kidney post-challenge of a TD antigen keyhole limpet hemocyanin (KLH) in vivo . Following recombination Oreochromis niloticus IL10 ((r)OnIL10) protein stimulation in vitro , the up-regulation of OnCD27 expression was detected during the process of B cell differentiation. Further, analysis of OnCD27 expression in different B cell subsets revealed that the OnCD27 expression in P50 plasma-like cells was remarkable higher than P60 plasmablast-like and P70 naïve mature B cells. Moreover, the OnCD27 transcripts presented a higher expression level in IgM lo plasma-like cells than IgM hi activated B cells. In summary, the collective results may provide that OnCD27 plays roles in T cell-dependent response and B cell differentiation in Nile tilapia.