Cloning and expression of bovine (Bos indicus) interleukin-2 in Escherichia coli

The gene for interleukin-2 (IL-2) was amplified from cDNA pool prepared from ConA-stimulated peripheral blood mononuclear cells (PBMCs) isolated from Indian cattle (Bos indicus). The amplified IL-2 gene was cloned and nucleotide sequences were determined. Homology comparison of nucleotide and predicted amino acid sequences revealed similarity of sequence and conservation of crucial amino acids with exotic cattle (B. taurus). The coding sequence of IL-2 (without its own signal sequence) was subsequently expressed as fusion protein with polyhistidine fusion tag in Escherichia coli, using prokaryotic expression vector. The expressed protein was present as insoluble inclusion bodies. The recombinant protein was solubilized with urea and purified using Ni-agarose affinity chromatography. The purified recombinant IL-2 was characterized in SDS-PAGE and in western blotting.