Comparison of Serological and Chemical Characteristics of Capsular Polysaccharides of Cryptococcus neoformans var. neoformans Serotype A and Cryptococcus albidus var. albidus

Abstract

The antigenic formula and chemical structure of capsular polysaccharide (CPS) of Cryptococcus albidus var. albidus (C. albidus) were studied in relation to those of C. neoformans var. neoformans serotype A (C. neoformans A). The results of slide agglutination tests with factor sera and reciprocal adsorption experiments showed that antigenic formula of C. albidus was the same as that of C. neoformans A. The soluble CPSs from the two species were obtained from culture supernatants by precipitation with ethanol followed by purification by chromatography on DEAE-cellulose column. The structural analyses of such CPSs from the two species showed that the antigenic CPS fractions consisted of a backbone of a(1-3)-linked D-mannopyranosyl residues with a single branch of P(1-2)-xylose or glucuronic acid, and mostly with O-acetyl groups, in which side chains and O-acetyl groups were responsible for antigenic specificity. It was found that there was a minor difference between the CPS of C. neoformans A and that of C. albidus; in the former, unsubstituted mannose residues existed in a low frequency, but in the latter none. Moreover, the 1H-nuclear magnetic resonance spectra of partially hydrolyzed acidic fragments of the two CPSs indicated that two xylose side chains were present between glucuronic acid side chains. Taken together, it was suggested that these two species of C. neoformans A and C. albidus are closely related to each other in their CPSs.

Structural studies of the capsular polysaccharide of a non-neoformans Cryptococcus species identified as C. laurentii, which was reclassified as Cryptococcus flavescens, from a patient with AIDS

“…14;15 The polysaccharide fraction investigated here was eluted from DEAE-Toyopearl column with 0.15 M NaCl under the same conditions as described for the major fraction of C. neoformans. 7 Although the oligosaccharides containing glucuronic acids were very similar to those derived from C. neoformans polysaccharides, striking differences were observed. The results of methylation analysis suggested that the mannose residue substituted at C-2 with glucuronic acid has also the mannosylxylose substituent at C-6 position.…”

A survey of heterobasidiomycetous yeasts for the presence of the genes homologous to virulence factors of Filobasidiella neoformans, CNLAC1 and CAP59 b bThe GenBank accession numbers for the sequences determined in this work are AF337642, L22866, AF337643, AF337644 and AF337645.

“…The GXM of polysaccharides isolated from Filobasidium species (C. albidus var. albidus) is reported to have a structural resemblance to that of F. neoformans (Ikeda et al, 1991). The major capsular polysaccharide from Tremella mesenterica is also GXM with some variation : the xylose side chain is composed of multimers instead of monomer (Slodki, 1966).…”

“…The species forming large capsules mostly belonged to the Tremellales and Filobasidiales (Fell et al, 2000). Since the major polysaccharide produced by species of Filobasidiella, Filobasidium, Tremella and Cryptococcus is known to be GXM (Abercombie et al, 1960 ;Cherniak et al, 1988 ;Ikeda et al, 1991 ;Slodki, 1966), we assumed that the genes involved in polysaccharide formation were conserved among these yeasts. Fig.…”

Characterization of an extracellular enzyme system produced by Micromonospora chalcea with lytic activity on yeast cells

“…1996 ). Moreover, the presence of capsular polysaccharides superimposed to the cell wall in Cryptococcus species could also account for the negative results of lysis in these yeasts ( Ikeda et al . 1991 ).…”