Abstract: The porcine interleukin-6 (PoIL-6) mature peptide gene was amplified from the total cellular RNA of porcine spleen cells induced by bacterial lipopolysaccharides (LPS) by RT-PCR, and the PCR production was subsequently cloned, sequenced and sub-cloned into the prokaryotic expression vector pQE30. The PoIL-6 mature peptide gene was expressed in E.coli JM109 and the expressed fusion recombinant protein (rPoIL-6) was purified under the innovated recombinant fusion protein purification method of denaturing by 8 mol/L urea, refolding by a self-innovative renaturation buffer and dialyzing by PBS buffer etc. The porcine IL-6 ELISA assay was used to detect the specifically immunological activity of the rPoIL-6 protein, and the cell proliferation activity induced by rPoIL-6 protein was assessed by MTS assay. The result showed that the PoIL-6 mature peptide gene with a length of 555 bp was successfully cloned, expressed, and purified with the molecular mass of about 20 ku and more than 95% pure on SDS-PAGE, which indicated the correct PoIL-6 fusion protein had been obtained. The rPoIL-6 protein could specifically react with McAb aginast rPoIL-6 and significantly promote the proliferation of porcine spleen lymphoblast cells.

Key words: porcine interleukin-6; prokaryotic expression; purification; activity assay