CLONING OF CERVINE INTERFERON-GAMMA CDNA BY POLYMERASE CHAIN-REACTION

As the first step in the development of a cervine IFN-gamma assay for the diagnosis of tuberculosis in deer, cervine IFN-gamma cDNA was ampl ified by polymerase chain reaction using primers based on the bovine I FN-gamma sequence. A high level of amino acid homology was found betwe en the cervine and the ovine and bovine sequences (94% and 91% respect ively). There was less identity with the porcine, human, mouse and rat sequences (78%, 62%, 37% and 39%, respectively). The amino terminus o f the mature IFN-gamma protein, which is critical for interaction with its receptor and for triggering biological activity, is highly conser ved between the cervine, bovine and ovine proteins. A monoclonal antib ody-based sandwich enzyme immunoassay (EIA) specific for bovine IFN-ga mma also detects ovine but not cervine IFN-gamma. This suggests that t he antibodies recognise epitopes common to the bovine and ovine protei n but not cervine IFN-gamma. Seven amino acid residues that were commo n to the bovine and ovine sequence differed in the cervine sequence, s uggesting that the specificity of the monoclonal antibodies may be dep endent on one or more of these residues. The possibility of the develo pment of an EIA for cervine IFN-gamma as a commercial in vitro diagnos tic assay for tuberculosis in deer is discussed.