Cloning and sequence analysis of interleukin-2 gene in Gaoyou ducks.

[Objective] To clone and analyze the interleukin-2 (IL-2) gene in Gaoyou ducks. [Method] With total RNA isolated from peripheral lymphocytes of Gaoyou ducks as templates, one pair of primers was designed according to the known IL-2 gene sequence in ducks. The IL-2 DNA was amplified by the RT-PCR and inserted into pGEM-T-easy vector. Then the positive recombinant plasmid was sequenced. [Result] The amplified target fragment was 433 bp with the correct size as theoretically expected. The open reading frame (ORF) was 423 bp encoding a precursor protein with 140 amino acids which consisted of a signal peptide composed of 21 amino acids and a mature peptide composed of 119 amino acids. The protein was approximately 13.66 kDa and contained one N-glycosylation site. The sequence of IL-2 gene of Gaoyou duck had 99.8% nucleotide homology to that of Anas platyrhynchos duck, Gushi duck and Shaoxing duck, respectively. It also had 99.3% nucleotide homology to that of Guangzhou duck. [Conclusion] The coding region of IL-2 gene of ducks is highly conserved.