In vitro release of interferon-γ by trichophytin-stimulated whole blood cell cultures from ringworm-vaccinated and control calves experimentally inoculated with Trichophyton verrucosum

Of a group of seven calves, four were vaccinated against bovine ringworm with the vaccine Ringvac bovis LTF-130 (Alpharma. Oslo, Norway), while three calves were left unvaccinated. All calves were inoculated epicutaneously with a virulent strain of Trichophyton verrucosum. Clinical signs were recorded. In response to stimulation with trichophytin, in vitro interferon-gamma (TFN-gamma) production in whole blood cell cultures was assessed in samples obtained pre-and post-vaccination and pre- and post-inoculation. A commercial enzyme immunoas-say kit was used to measure IFN-gamma levels (Bovigam, CSL, Victoria, Australia). Control calves developed typical ringworm lesions, whereas vaccinated calves did not. Following vaccination, release of IFN-gamma in whole blood cell cultures indicated the presence of circulating trichophytin-specific lymphocytes. After inoculation with T. verrucosum, IFN-gamma production was demonstrated in samples from both vaccinated and control calves. This study showed that vaccination with Ringvac bovis LTF-130 elicits a protective immune response suggesting involvement of the cellular branch of the immune system. Experimental infection of naive nonvaccinated calves with T. verrucosum, also indicated stimulation of a cell-mediated immune response essential for resolution of lesions.