EXPERIMENTAL IMMUNITY TO MICROSPORUM-CANIS AND CROSS-REACTIONS WITH OTHER DERMATOPHYTES OF VETERINARY IMPORTANCE

An inactivated, broad-spectrum dermatophyte vaccine was used to produc e an active immunity in guinea-pigs against Microsporum canis. None of the vaccinates developed infection from a contact exposure challenge that produced clinical infections in 70% of the unvaccinated controls. Infection with M. canis induced antibody titres (ELISA) and delayed c utaneous hypersensitivity (DCH) reactions to itself as well as cross-r eacting titres to Trichophyton equinum and T. mentagrophytes and DCH r eactions to T. mentagrophytes; however, vaccinated animals developed s ignificantly higher antibody titres and DCH responses to all of these antigens than did non-vaccinated animals which had been infected or ex posed. Rabbits hyperimmunized with culture filtrate antigens to single dermatophyte agents (M. canis, M. gypseum, T. equinum, and T. mentagr ophytes) developed positive inter-species and inter-generic DCH cross- reactions to a battery of six skin test antigens (M. canis, M. gypseum , M. equinum, T. equinum, T. mentagrophytes var. mentagrophytes and T. verrucosum). Guinea-pigs vaccinated with a T. equinum vaccine had inc reased resistance to M. canis infection than did non-vaccinated contro ls. These findings support clinical observations which suggest establi shment of a broad-based immunity in animals following infection with a single dermatophyte.