Expressed gene sequence and bioactivity of the IFNγ-response chemokine CXCL11 of swine and cattle

This report describes the cloning and characterization of expressed gene sequences of the swine and bovine interferon-gamma inducible chemokine CXCL11, or I-TAC, associated with type 1 T-helper immune responses, and affirmation of bioactivity of their yeast-expressed protein products. The coding regions of both cDNA sequences were 303 nucleotides in length; each is coded for four exons in the genome. The bovine coding region shared 82% and 70% homology with human and mouse CXCL11, respectively, and the swine coding region 84% and 72% homology, respectively. As expected the swine and bovine CXCL11 sequences showed less homology with other human and mouse C-X-C motif chemokine sequences. Each cDNA was cloned into plasmids and transfected into Pichia pastoris (yeast) and the resultant expressed protein purified. Biological activity of each purified chemokine was affirmed by chemotaxis assays. Both swine and bovine CXCL11 were chemotactic for mitogen and IL-2 stimulated peripheral blood mononuclear cells. This is the first report for bioactivity of this chemokine in livestock species. This work provides valuable new reagents for investigating basic immunity as well as vaccine and disease responses in swine and cattle, goals of the U.S. Veterinary Immune Reagent Network which supported this effort.