Adherence of Candida albicans to human salivary components adsorbed to hydroxylapatite

Abstract

Colonization of the oral cavity by Candida albicans involves adherence of yeast cells to oral surfaces. An assay was developed to measure the attachment of C. albicans cells, metabolically labelled with [35S]methionine, to saliva-coated hydroxylapatite (SHA) beads--a model for the tooth surface. Using this assay approximately 1.26 x 10(6) C. albicans cells (50.5% of input cells) attached to the SHA beads (12 mg). Different strains of C. albicans adhered to varying degrees to SHA beads, but in general adherence was promoted by growth of cells at 28 degrees C and by starvation of cells for glucose. Proteins in human whole, or parotid, saliva samples were fractionated by gel filtration (Sephacryl S-200 column) and fractions were adsorbed to hydroxylapatite beads. Fractions that contained proline-rich proteins or statherin promoted attachment of C. albicans ATCC 10261 cells. Neuraminidase treatment of SHA beads, but not of cells, significantly increased yeast cell binding to the SHA beads. Neuraminidase activity in the oral cavity may unmask glycoprotein receptors involved in the adhesion of C. albicans to saliva-coated surfaces.