Ovine interferon-γ gene of indigenous sheep: Cloning, sequencing and expression studies in Escherichia coli

Ovine interferon-gamma (IFN-γ) cDNA was isolated from total mRNA of peripheral blood mononuclear cells from indigenous sheep by reverse transcription PCR. The cDNA was successfully cloned, sequenced and expressed in Escherichia coli as thioredoxin fusion protein. Sequence comparison of Indian sheep IFN-γ showed high nucleotide homology with published IFN-γ sequences of sheep and other species of ruminants. The cDNA codes for a mature polypeptide with a putative molecular weight of 17 kDa. The recombinant ovine IFN-γ, expressed in BL21 E. coli cells as His-tagged protein, was purified using Ni-chelation chromatography. Up to 250 μg of recombinant ovine IFN-γ could be obtained from 50 mL of bacterial culture. The production of this important cytokine has significant implications in therapy of major infectious diseases of small ruminants. It also has potential applications as adjuvant to enhance the protective efficacy of the existing vaccines.