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.