Cloning and high level expression of bovine interferon gamma gene in eukaryotic cells (COS 7)

Interferon gamma (IFN γ) is one of the key cytokines in defining T helper 1 lymphocyte immune responses. In this study, the bovine IFN γ gene was cloned from spleen tissue RNA using the reverse transcription polymerase chain reaction (RT PCR). IFN γ cDNA was sub cloned and expressed in mammalian expression plasmid (pcDNA3.1(+)) under the control of the human cytomegalovirus (CMV) promoter. The predicted amino acid (aa) sequence of bovine IFN γ compared with corresponding known sequence from bovine (Bos taurus) was 100% identity and with ovine, caprine, camel, lama, equine, canine, feline, human, mice and chicken cytokine was 95, 95, 86, 83, 77, 75, 75, 61, 44 and 35%, respectively. Invitro expression of recombinant bovine IFN γ (rBoIFN γ) and secretion to culture medium was confirmed by ELISA test. Maximum expression of rBoIFN γ occurred at 96 and 144 h after transfection in COS 7 cells. These results showed that pcDNA3.1 expression vector and COS 7 cells transfected by diethylaminoethyl (DEAE) dextran allowed the high level expression of bovine IFN γ gene and the release of protein in supernatant of cell culture.