Production and Characterization of Recombinant Canine Interferon-γ from Escherichia coli

We have used the recently cloned cDNA for canine interferon-γ (IFN-γ) to engineer bacteria to produce large amounts of the recombinant cytokine. The resulting protein can be recognized by monoclonal and polyclonal antibodies largely species specific for canine IFN-γ. The purified recombinant IFN-γ (rIFN-γ) also had biological activity in vitro in three assay systems: (i) vesicular stomatitis virus plaque inhibition, (ii) class II major histocompatibility complex antigen upregulation on canine kidney parenchymal cells, and (iii) amplification of in vitro tissue-associated lymphoproliferation, all known to be effected by native IFN-γ (nIFN-γ). The availability of large amounts of active canine rIFN-γ will be an important tool in studies of the role of this cytokine in the widely used experimental canine organ transplant model and also will be of diagnostic and therapeutic veterinary interest.