Expression of bovine interleukin 15 in Pichia pastoris and study on its biological activity: a T-cell activator.

Interleukin 15 (IL-15) plays crucial role as stimulatory cytokine in generation and proliferation of CD8(+) T memory cells. The present study was initiated to analyze the role of yeast-expressed bovine IL-15 in inducing the CD8(+) T memory cells. The bIL-15 was cloned in pPICZ alpha A expression vector. The expressed bovine IL-15 was purified by anion exchange chromatography and further characterized using SDS-PAGE and Western blotting. Biological activity of the purified protein was evaluated in vitro through induction of Bcl2 in IL-15 stimulated PBMCs was measured using qPCR and the phosphorylation of STAT3 was confirmed by immuno-staining of HEK273 cells. From the recent research studies, it was evident that the fatty acid oxidation catalyzed by Carnitine Palmitoyl Transferase 1a (Cpt1a) is a critical step during the conversion of effector CD8(+) T cells to memory CD8(+) T cells which is induced by IL-15. There were no research studies revealed the role of IL-15 on activating memory CD8(+) T cells by influencing the Cpt1a in Bovines was documented; yet and in the present study, we evaluated that bovine IL-15 could induce the expression of Cpt1a in IL-15 treated bovine PBMCs and helps in memory cell induction.