Structures of cell wall mannans of pathogenic Candida tropicalis IFO 0199 and IFO 1647 yeast strains

We conducted a structural analysis of the cell wall mannans isolated from two Candida tropicalis strains, IFO 0199 and IFO 1647, exhibiting strong agglutinabilities against anti-Candida factor sera 5 and 6. The products released from these mannans by acid treatment were identified as the oligosaccharides, from biose to pentaose, consisting solely of β-1,2-linked mannopyranose units corresponding to common epitopes of Candida albicans serotypes A and B (factor 5). Mild acetolysis of acid- and alkali-treated mannans produced large amounts of hexaose and heptaose, Manpβ1-2Manpβ1- 2Manpα1-2Manpα1-2Manpα1-2Man and Manpβ1-2Manpβ1-2Manpβ1-2Manpα1- 2Manpα1-2Manpα1-2Man, corresponding to the C. albicans serotype A-specific epitopes (factor 6). However, the homologous pentaose, Manpβ1-2Manpα1- 2Manpα1-2Manpα1-2Man, was not generated by this procedure. The oligosaccharides (biose to hexaose) obtained from the mannans by conventional acetolysis were composed exclusively of α-1,2-linked mannopyranose units. Therefore, the mannans of C. tropicalis IFO 0199 and IFO 1647 do not have the α-1,3-linked mannopyranose units previously observed in the mannans of C. albicans and Candida stellatoidea. The results of this study and previous findings indicate that the similarity of the antigenicities of three Candida species, C. albicans serotype A, C. stellatoidea type II, and C. tropicalis, reside in the β-1,2 and α-1,2 linkages containing oligomannosyl side chain (factor 6) in the cell wall mannan.