Submitted to: Avian Immunology Research Group Abstract
Publication Type: Proceedings
Publication Acceptance Date: April 4, 2001
Publication Date: N/A
Interpretive Summary: Comprehensive understanding of various effector molecules which mediate critical immune function is important in our understanding of host immune system in livestock and poultry. In this report, ARS scientists identified and cloned two major chicken cytokine genes which are secreted by lymphocytes and studied their biochemical and molecular nature. The results showed that these two cytokines are expressed on various tissues and mediate important immune function in chickens. Better understanding of how the lymphocyte-secreted factors enhance host immunity will lead to novel strategies to enhance poultry health.
Full length cDNA encoding chicken IL-15 designated as pc3.1/5101, was isolated from chicken liver cDNA library and additional sequences were obtained using 5' rapid amplification of cDNA ends. The full-length chicken IL-15 cDNA contains and open reading frame of 187 amino acids with a single potential N-linked glycosylation site. The predicted protein sequence shows similarities of 55%, 53% and 52% with mouse, human and bovine IL-15 sequences, respectively. The pc3.1/5101 has total 699 bp including the 561 bp open reading frame with a predicted m.w. of 21,964 kDa. Chicken IL-15 contains all 4 highly conserved cysteine residues present in mammalian IL-15 sequences, including 2 upstream AUGs of the 5' UTR. Recombinant chicken IL-15 (rchIL-15) was expressed in prokaryotic and eukaryotic expression systems and their distribution, molecular, biochemical and functional characterizations were compared tot he chicken IL-2. Northern blotting analysis demonstrated that the chicken IL-15 gene is expressed in many tissues including liver, cecal tonsil, muscle, heart, intestine and spleen whereas IL-2 was only expressed in the concanacalin-A (Con A)-stimulated spleen cells. Collectively, these results indicate that the pc3.1/5101 gene represents an avian homologue of mammalian IL-15.