Submitted to: Infection and Immunity
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/29/2006
Publication Date: 11/30/2006
Citation: Hong, Y.H., Lillehoj, H.S., Dalloul, R.A., Miska, K.B., Tuo, W., Lee, S., Han, J., Lillehoj, E.P. 2006. Molecular cloning and characterization of chicken NK lysin. Infection and Immunity. 110:339-347. Interpretive Summary: With increasing concerns over the use of drugs in animal production and wide spread drug resistance incidence associated with commonly used drugs, discovery of novel compounds which are naturally produced by animal's own immune system and has anti-microbial activity against wide variety of pathogens will be important. In this paper, ARS scientists describe a novel anti-microbial peptide which is secreted by bird's lymphocytes. This novel peptide called NK-lysin is produced by lymphocytes of poultry and its production is highly enhanced during parasitic infection indicating protective role of NK-lysin in infections. The full-length gene encoding chicken NK-lysin was cloned and recombinant NK-lysin protein was produced. Recombinant NK-lysin protein kills chicken tumor cells and demonstrates lytic activity against coccidia parasites. In conclusion, the gene encoding chicken NK-lysin has been cloned and it shows a great potential as a novel immunotherapeutic agent against coccidia parasites. This information will help industry to devise a novel method to control coccidiosis.
Technical Abstract: NK lysin is an anti microbial and anti tumor protein expressed by NK cells and T lymphocytes. In a previous report, we identified a set of overlapping expressed sequence tags constituting a contiguous sequence (contig 171) homologous to mammalian NK lysins. In the current report, a cDNA encoding NK lysin was isolated from a library prepared from chicken intestinal intraepithelial lymphocytes (IELs). It consisted of an 868 bp DNA sequence with an open reading frame of 140 amino acids and a predicted molecular mass of 15.2 kDa. Comparison of its deduced amino acid sequence showed less than 20% identity to mammalian NK lysins. The tissue distribution of NK lysin mRNA revealed highest levels in bursa lymphocytes, intermediate levels in peripheral blood, splenic, and intestinal intraepithelial lymphocytes, and lowest levels in thymic lymphocytes. Following intestinal infection of chickens with Eimeria maxima, one of seven Eimeria species causing avian coccidiosis, NK lysin transcript levels increased 3 to 4 fold in CD4+ and CD8+ intestinal IELs. However, cell depletion experiments suggested other T lymphocyte subpopulations also expressed NK lysin. The kinetics of NK lysin mRNA expression indicated that, whereas infection with E. acervulina induced maximum expression only at 7 8 days post infection, E. maxima and E. tenella elicited biphasic responses at 3 4 and 7 8 days post infection. Finally, recombinant chicken NK lysin expressed in COS7 cells exhibited anti tumor cell activity against LSCC RP9, a retrovirus transformed B cell line. We conclude that chicken NK lysin plays important roles during anti microbial and anti tumor defenses.