Characterization of a major cell wall antigen and potential adhesin in three strains of Candida albicans.

Selected strains of Candida albicans were examined to reveal the surface antigenicity and biochemical nature of major cell wall proteins that also were shown to serve as cellular adhesins on human buccal epithelial cells. Confirmation of the adhesive properties of these cells was made by scanning electron microscopy and immunofluorescence microscopy. Particular attention was directed at the clinical isolate KM-302. By means of indirect immunofluorescence staining, the KM-302 blastoconidia absorbed rabbit anti-C. albicans ATCC-32354 serum, revealing specific localization of surface antigens on germ tubes and pseudohyphae. Extracellular polymeric material and the cell wall extract of C. albicans KM-302 blastoconidia were found to contain a major surface antigen of 49 kDa that exhibited 42% adhesion inhibition in vitro. Of considerable significance is that immunogold localization by electron microscopy showed the antigen to be almost exclusively cell wall bound. This major antigen, identified in affinity and gel filtration chromatography fractions, was composed of 4% carbohydrate and 95.7% protein and had an isoelectric point of 6.1. The major antigen also showed a high level of similarity with that of C. albicans strain SC-5314 inasmuch as the major antigen of that strain had carbohydrate and protein compositions of 4 and 95.5%, respectively. Both of these strains also possessed the same percent of adhesion inhibition on human buccal epithelial cells.