ATTACHMENT OF SPORES OF THE HUMAN PATHOGENIC FUNGUS RHIZOPUS-ORYZAE TO EXTRACELLULAR-MATRIX COMPONENTS

Fungi of the order Mucorales determine various infections involving pr incipally the respiratory tract. In spite of their medical importance, little is known about their mechanisms of adherence to the host tissu es. Thus we have attempted to define the morphological stages involved in the adherence process of Rhizopus oryzae which is the main causati ve agent of mucormycoses. The study of the kinetics of germination and adherence to plastic revealed that attachment occurred prior to germi nation and decreased dramatically with germ tube formation, This corre lates with important modifications of the cell wall of the fungus with respect to both carbohydrate composition and distribution of anionic sites. Moreover, the attachment of spores to extracellular matrix comp onents immobilized onto wells of polystyrene microtiter plates has bee n investigated, Spores adhered readily to immobilized laminin or type IV collagen, but not to fibronectin or tile glycosaminoglycans. Attach ment to laminin and collagen,vas dose-dependent and specific, Adhesion ,vas not inhibited by the different carbohydrates tested, suggesting t hat a lectin was not involved in these interactions. Finally, immunofl uorescence revealed that laminin and type IV collagen interacted exclu sively with spores and mother cells of germ tubes, Thus, the recogniti on of laminin or collagen by spores may participate in their adherence to epithelial basement membranes exposed after epithelial tissue dama ge which frequently accompanies the predisposing factors for mucormyco ses.