A new member of RIO kinase 1 protein family (RIOK-1 ) was identified in Tilapia Oreochromis niloticus immunized by killed Flavobacterium columnarae. Suppressive subtractive hybridization (SSH) was utilized to construct a cDNA library and quantitative RT-PCR analysis used to examine Oreochromis niloticus Riok1 gene expression. The complete sequence of the RIOK-1 cDNA is composed of 2226 bps with 10 open reading frames , the predicted gene product is 742 amino acids with molecular weight of 190.41 kDa
Analysis using q uantitative RT-PCR revealed that the gene encoding RIOK-1 was broadly and strongly expressed in tissues of the stimulated fish, as up-regulated gene suggesting that this member of RIOK-1 genes is probably involved in the general immune response against the pathogenic bacteria.