Abstract

Paracoccioiodes brasiliensis is a thermally dimorphic fungus that is the etiological agent of paracoccidiodomycosis. This yeast cells has been subjected to a number of chemical studies intended to analyze cell wall components (proteins, glycoproteins, glycolipids, and polysaccharides) that can modulate host-parasite relationships through interactions with the host immune system. The composition and chemical structure of the polysaccharide of the cell wall varies among the different fungal species. The antigenic relationship between strains the yeast phases have been little explored in P. brasiliensis. The present study was to compare the carbohydrate composition of the antigens of seven strains of P. brasiliensis, prepared according to the same protocol. P. brasiliensis yeast cells, ED01, 01, 03, 18, 192, 339 and 1578 were extracted with 2% KOH at 100ºC. Crude polysaccharide fractions obtained from KOH extractions was investigated. Total carbohydrate was determined by the phenol-sulfuric acid method. The polysaccharides were hydrolyzed with trifluoroacetic acid. The resulting monosaccharides were characterized and quantified by gas chromatography (GC) as alditol acetate derivatives. Protein was measured by the method of Bradford. The GC analysis showed the presence of arabinose, xylose, mannose, galactose, glucose, N-glucosamine in this sequence: PbEDO1 - 2:5:20:11:62:0; Pb01 - 3:0:39:18:40:0; Pb03 - 4:12:28:8:48:0; Pb18 - 0:0:10.6:7.3:79.2:2.3; Pb192 - 1:1:69:25:4:0; Pb339 - 2:6:60:7:25:0; Pb1578 - 3:9:19:8:61:0. Only one strain Pb18 was showed 9.8% of protein. The present results demonstrated different ratio of monosaccharide between various strains of P. brasiliensis. These data suggest that different isolates may present variable composition of protein and antigen components under constant culture conditions. The mechanisms involved in the antigenic variability are yet unknow and further studies will be necessary.