Molecular cloning and characterization of a novel bovine IFN-ε.

A bovine IFN-ε (BoIFN-ε) gene was amplified from bovine liver genomic DNA consisting of a 463bp partial 5'UTR, 582bp complete ORF and 171bp partial 3'UTR, which encodes a protein of 193 amino acids with a 21-amino acid signal peptide and shares 61 to 87% identity with other species IFN-ε. Then BoIFN-ε gene was characterized, and it can be transcribed in EBK cells at a high level after being infected by VSV. Recombinant proteins were expressed in Escherichia coli and the antiviral activity was determined in vitro, which revealed that bovine IFN-ε has less antiviral activity than bovine IFN-α. In addition, an immunofluorescence assay indicated that BoIFN-ε expressed in MDBK cells could be detected by polyclonal antibody against BoIFN-ε. Furthermore, the BoIFN-ε gene can be constitutively expressed in the liver, thymus, kidney, small intestine and testis, but not in the heart. This study revealed that BoIFN-ε has the typical characteristics of type I interferon and can be expressed constitutively in certain tissue, which not only can be a likely candidate for a novel, effective therapeutic agent, but also facilitate further research on the role of bovine IFN system.