Cloning and sequencing of badger (Meles meles) interferon γ and its detection in badger lymphocytes

The European badger (Meles meles) has been identified as a reservoir for Mycobacterium bovis and is implicated in the maintenance and transmission of tuberculosis in cattle. There is a need for a sensitive test of M. bovis infection in badgers and the current serodiagnostic test used for this purpose has low sensitivity. As observed for other species, assay of interferon-gamma (IFNγ) produced in response to M. bovis antigens is a more sensitive test of tuberculosis. With this objective in sight, we report the first step in the development of an ELISA for badger IFNγ. The badger IFNγ gene was cloned and sequenced and used to generate a specific polyclonal antibody to the cytokine. The gene sequence demonstrated regions that were conserved within the IFNγ genes of other mammals. The badger sequence was most similar to the canine, showing similar structural organisation of the gene and 88% amino acid identity. Rabbits were immunised with DNA encoding badger IFNγ and the resulting polyclonal antiserum demonstrated specificity for canine IFNγ by immunoblot of a commercial recombinant canine IFNγ. The antiserum was used to detect intracellular badger IFNγ by flow cytometry analysis of badger lymphocytes stimulated with mitogen.