Non-specific cytotoxic cell receptor (NCCRP)-1 type gene in tilapia (Oreochromis niloticus): its cloning and analysis.

Non specific cytotoxic cells are natural killer cell equivalent in teleosts. These cells are known to mediate innate immune responses in fishes. In this study, from tilapia, a non-specific cytotoxic cell receptor protein (NCCRP) like cDNA composed of 960 bps with a 12 bps 5' UTR, 702 bps open reading frame and 246 bps 3' UTR has been cloned. The predicted gene product is 233 amino acid with a molecular weight of 26.6 kDa and pI of 6.07. The gene has a typical F-box associated domain, which harbors the antigen binding region, implicated in formation of conjugates with target cells necessary for killing. By semi-quantitative RT-PCR studies, the expression level of NCCRP-1 was highest in liver followed by head kidney, spleen and intestine. Low expression levels were recorded in brain, gill and heart. Lowest expression of transcripts was in the skin. As evidenced by in situ hybridisation the NCCRP-1 transcripts were expressed on lymphocyte like cells as well as neutrophils.