Identification and Comparative Expression Analysis of Interleukin 2/15 Receptor beta Chain in Chickens Infected with E. tenella

Abstract

Background: Interleukin (IL) 2 and IL15 receptor beta chain (IL2/15R beta, CD122) play critical roles in signal transduction for the biological activities of IL2 and IL15. Increased knowledge of non-mammalian IL2/15R beta will enhance the understanding of IL2 and IL15 functions. Methology/Principal Findings: Chicken IL2/15R beta (chIL2/15R beta) cDNA was cloned using 5'/3'-RACE. The predicted protein sequence contained 576 amino acids and typical features of the type-I cytokine receptor family. COS-7 cells transfected with chIL2/15R beta produced proteins of approximately 75 and 62.5 kDa under normal and tunicamycin-treated conditions, respectively. The genomic structure of chIL2/15R beta was similar to its mammalian counterparts. chIL2/15R beta transcripts were detected in the lymphoblast cell line CU205 and in normal lymphoid organs and at moderate levels in bursa samples. Expression profiles of chIL2/15R beta and its related cytokines and receptors were examined in ConA-stimulated splenic lymphocytes and in ceca-tonsils of Eimeria tenella-infected chickens using quantitative real-time PCR. Expression levels of chIL2/15R beta, chIL2R alpha, and chIL15R alpha were generally elevated in ceca-tonsils and ConA-activated splenic lymphocytes. However, chIL2 and chIL15 expression levels were differentially regulated between the samples. chIL2 expression was upregulated in ConA-activated splenic lymphocytes, but not in ceca-tonsils. In constrast, chIL15 expression was upregulated in ceca-tonsils, but not in ConA-activated splenic lymphocytes. Conclusions/Significance: We identified an avian form of IL2/15R beta and compared its gene expression pattern with those of chIL2, chIL15, chIL2R alpha, and chIL15R alpha. Our observations suggest that chIL15 and its receptors, including chIL2/15R beta, play important roles in mucosal immunity to intestinal intracellular parasites such as Eimeria.