VIRULENCE FACTORS OF MEDICALLY IMPORTANT FUNGI

Human fungal pathogens have become an increasingly important medical p roblem with the explosion in the number of immunocompromised patients as a result of cancer, steroid therapy, chemotherapy, and AIDS. Additi onally, the globalization of travel and expansion of humankind into pr eviously undisturbed habitats have led to the reemergence of old fungi gi and new exposure to previously undescribed fungi. Until recently, relatively little was known about virulence factors for the medically important fungi. With the advent of molecular genetics, rapid progress has now been made in understanding the basis of pathogenicity for org anisms such as Aspergillus species and Cryptococcus neoformans. The tw in technologies of genetic transformation and ''knockout'' deletion co nstruction allowed for genetic tests of virulence factors in these org anisms. Such knowledge will prove invaluable for the rational design o f antifungal therapies. Putative virulence factors and attributes are reviewed for Aspergillus species, C. neoformans, the dimorphic fungal pathogens, and others, with a focus upon a molecular genetic approach. Candida species are excluded from coverage having been the subject of numerous recent reviews. This growing body of knowledge about fungal pathogens and their virulence factors will significantly aid efforts t o treat the serious diseases they cause.