The role of Candida albicans secreted aspartic proteinase in the development of candidoses

Although Candida albicans infections in humans are increasingly frequent, our understanding of the host-parasite relationship is limited. The secreted aspartic proteinase of C. albicans was first described in 1965 and has proved to be a major factor in virulence. This enzyme belongs to the class of aspartic proteinases which includes pepsin and renin in humans. Although found in some fungi, secreted aspartic proteinase is rare in these organisms. While the existence of several isoenzymes may not be fully established, it is now obvious that at least seven different genes encode for secreted aspartic proteinase. Within Candida cells it is located in membrane-bound vesicles. Upon fusion of these subcellular structures within the plasma membrane, the enzyme is released to the environment. In the context of human mucosal diseases it is responsible both for adhesion and invasion. Strains from HIV-infected patients with oral candidosis generally exhibit higher enzymatic activity than control strains. In future secreted aspartic proteinase may prove a prime target for new types of antimycotics.