During the last few years, reports have appeared claiming that lufenuron diminished or even cured dermatophyte infections in cats and dogs. As these observations have a rather anecdotal character leading to some ambiguity in the literature, it was decided to test lufenuron in a generally accepted animal model for dermatomycotic infection. The test was carried out in guinea pigs artificially infected with Microsporum canis on scarified dorsal skin and orally treated with lufenuron (Programä). The efficacy of up to five doses of 80 mg/kg was assessed 7 and 14 days after the start of treatment. All animals failed to show any improvement in skin lesions as compared to the vehicle-only treated animals. Clinical symptoms taken into account were scaling, crust formation, erythema, and exudation. Neither the number of treatments (one or five) nor the dose range (40 or 80 mg/ kg) made any difference. Itraconazole, tested earlier under identical circumstances, resulted in a clear and consistent improvement at day 7 of the infection at a dose of 15 mg/kg, given either in one dose or spread over several days. The absence of antimycotic activity of lufenuron in this established animal model constitutes a significant element in the discussion on the antifungal potency of lufenuron and supports the fact that there is, as yet, no evidence that benzoylphenyl urea derivative compounds have an effect on chitin synthesis in fungi. Funding: J&J Pharmaceutical Research and Development, Janssen Animal Health. FC-2The role of endogenous protein inhibitors of dermatophyte proteolytic activity M. DROBNIČ -KOSˇOROK, D. MIHELČ IČ , B. PREMROV, I. ZDOVC, P. ZRIMSˇEK and T. POPOVIČ Veterinary Faculty, University of Ljubljana, Ljubljana, Slovenia; Josef Stefan Institute, Ljubljana, Slovenia Microsporum canis and Trichophyton mentagrophytes produce different proteolytic enzymes necessary for their growth and progression. In general, enzymatic activity can be tightly regulated by various mechanisms, of which endogenous inhibitors are of great importance. Considering the fact that an imbalance between proteases and their inhibitors has been implicated in the pathogenesis of several diseases, the aim of our work was to investigate the production and role of protease inhibitors produced by fungi. Both dermatophytes were demonstrated to produce protein as well as low-molecular-weight inhibitors of different proteases. Protein inhibitors were isolated from culture medium and cytosolic extracts obtained from mechanically disintegrated mycelia by affinity chromatography on CM-Sepharose 4B or by HPLC separation in the case of low-molecular-weight inhibitors. The size of the purified proteins was analysed by SDS-PAGE, and their immunogenic properties by immunoblotting. Their inhibitory properties were determined by inhibition of trypsin, papain, and cathepsins B and L. Temperature and pH stability of the low-molecularweight inhibitors was established as well. From our data, it is evident that both protein and low-molecular-weight inhibitors of cysteine ...