Variation in cell surface hydrophobicity amongCryptococcus neoformansstrains influences interactions with amoeba

Abstract

ABSTRACTCryptococcus neoformansandCryptococcus gattiiare pathogenic fungi that cause significant morbidity and mortality. Cell surface hydrophobicity (CSH) is a biophysical parameter that influences the adhesion of fungal cells or spores to biotic and abiotic surfaces.C. neoformansis encased by polysaccharide capsule that is highly hydrophilic and is a critical determinant of virulence. In this study, we report large differences in the CSH of someC. neoformansandC. gattiistrains. The capsular polysaccharides ofC. neoformansstrains differ in repeating motifs, and therefore vary in the number of hydroxyl groups, which along with higher-order structure of the capsule, may contribute to the variation in hydrophobicity that we observed. ForC. neoformans, CSH correlated with phagocytosis by natural soil predatorAcanthamoeba castellani. Furthermore, capsular binding of the protective antibody (18B7), but not the non-protective (13F1) antibody altered the CSH ofC. neoformansstrains. Variability in CSH could be an important characteristic when comparing the biological properties of cryptococcal strains.IMPORTANCEThe interaction of a microbial cell with its environment is influenced by the biophysical properties of a cell. The affinity of the cell surface for water, defined by the Cell Surface Hydrophobicity (CSH), is a biophysical parameter that varied amongst different strains ofCryptococcus neoformans. The CSH influenced the phagocytosis of the yeast by its natural predator in the soil, Amoeba. Studying variation in biophysical properties like CSH gives us insight into the dynamic host-predator interaction, and host-pathogen interaction in a damage-response framework.