THE ROLE OF SECRETORY AND STRUCTURE-ASSOCIATED PROTEINASES OF ASPERGILLUS-FUMIGATUS IN THE PATHOGENESIS OF INVASIVE ASPERGILLOSIS

In the course of invasive aspergillosis, Aspergillus fumigatus is capa ble of penetrating any tissue of the host. Secretory proteinases of th e fungus might facilitate the hyphae to grow through fibrillar protein s like elastin and collagen. However; using systemic infection models, no significantly reduced virulence could be shown with fungal mutants deficient for all known secretory proteinases. Thus, secretory protei nases might he of minor relevance for the pathogenesis of invasive asp ergillosis. In addition, microscopic examination of aspergilli penetra ting vessel walls did not reveal obvious lysis of wall proteins, thus emphasizing a mechanical disruption of fibrillar proteins by the growi ng hyphae. However, a strictly localized proteolysis at the tips of gr owing hyphae caused by wall associated proteinases might be involved. Candidates for such a mechanism are the activities of aspartic and ser ine proteinases which we have discovered in the cell wall fraction of A. fumigatus.