Distinct isoforms of secreted aspartyl proteinases (Sap) of Candida albicans are important virulence factors for different types of candidosis. Predominant expression of Sap1-3 has been shown to be crucial for superficial infections in experimental mucosal and cutaneous candidosis, whereas Sap4-6 might be important for systemic disease. This in-vivo study investigated Sap expression in two samples from patients with oral candidosis and from cutaneous infection. Two different polyclonal antibodies directed against Sap1-3 and Sap4-6 were used for ultrastructural characterisation of protein localisation and expression. Post-embedding immuno-electron microscopy revealed Sap1-3 and Sap4-6 immunoreactivity in all samples. All C. albicans cells expressed predominantly the proteinases Sap1-3 which were evenly distributed within the cell wall and cytoplasmic membrane. In contrast, Sap4-6 labelling was only evident in a few fungal cells. In particular it was localised at the tips of hyphal cells during invasion. These data suggest a different pathogenetic role for Sap1-3 and Sap4-6 during host-fungal interaction.
Adult Aged