Four strains of HistopIasma capsulatum were analyzed to observe any variations in their cell wall composition. Strair~ G-184B produced the same amount of sugars reported by Domer (2) although qualitative analyses agreed with Kanetsuna's report (4) as far as the presence of glucose, galaetose, and mannose was concerned. Our results agree with previous reports in classifying H. capsutatum into chemotypes I and II, the latter having more ~-glucan in its cell wall. A decrease in the amount of fraction 2 (e-glucan) of strain G-184B was observed when the strain was subcultured in vitro for many years, an effect similar to that reported for Paracoccidioides brasiliensis (12,13).Histoplasma capsulatum, the causative agent of histoplasmosis, is a dimorphic fungus which grows in a filamentous fashion (M form) in soil, or in vitro at 23°C, and as a budding yeast (Y form) in the infected host or in vitro at 37°C.To elucidate some aspects related to dimorphism on H. capsulatum, Domer, Hamilton, and Harkin (3) studied both the Y and M cell wall compositions of strain SwB, concluding that the yeast cell wall contained more chitin and less mannose and amino acids than the mycelial cell wall. Later, Berliner (1) described two morphological types in H. capsulatum, types A (albino) and B (brown), which differed in their M phase morphologies, their Y phases being indistinguishable. Type A mycelia grew as white colonies without diffusible pigment, with broad, white, aereal hyphae, few macroconidia and many microconidia, whereas type B mycelia grew as pigment-producing brown colonies with narrow, brown, fiat hyphae, many macroconidia and few microconidia.Almost simultaneously with Berliner's report, Pine and Boone (7) on the basis of combined serological and chemical data, showed that two major serotypes could be distinguished chemically; strains were later separated by Domer into chemotypes I and II (2). These studies, and another one by Kanetsuna et al. (4) indicated that each of Berliner's types A and B could be subdivided into Domer's chemotypes, the main difference being the presence of c~-glucan in the yeast cell wall of chemotype II and its absence from chemotype I.A closely related fungus, Paracoccidioides brasiliensis, has also been reported to have e-glucan in its yeast cell wall (5) although its amount varies as a function of the culture medium, being virtually lost when cultured in vitro for long periods of time (12). A hypothesis has been proposed (12, I3) by which this polysaccharide keeps a close relationship to virulence in this microorganism It would therefore be of interest to relate the presence or absence of this carbohydrate polymer to the virulence of strains of H. capsulatum. As a first step to explore such a relationship, the yeast phase cell walls of four strains belonging to the types and chemotypes described, were analyzed chemically in regard to their glycan composition. 279Med Mycol Downloaded from informahealthcare.com by Flinders University of South Australia on 02/07/15For personal use only.

Differences in cell wall structure of Paracoccidioides brasiliensis strains isolated from localized or disseminated cases of paracoccidioidomycosis and from soil emphasize the importance of standardization if results obtained in different laboratories are to be compared.The cell wall of Paracoccidioides brasiliensis is a changing structure whose composition depends not only on the morphological phase, yeast or mycelium, from which the wall is isolated [4] but also on the origin of the strain and culture conditions [6].To confirm the last statement, five P. brasiliensis strains of different origin were studied with respect to their yeast cell wall structure. Strains IVIC Pb281, IVIC Pb282, and IVIC Pb289, are derivatives of strains 8285, 9570 and 6688 from the Instituto Nacional de Dermatologia, Caracas, Venezuela. These strains were isolated 1-3 years ago from patients with disseminated paracoccidioidomycosis. Strain IVIC Pb294 is a derivative of strain 7861 from the same source, isolated from a patient with a localized paracoccidioidomycosis. Strain IVIC Pb292 is a derivative of strain T1 isolated from mice inoculated with a soil suspension [1]. All these strains were maintained in vitro in GGY agar medium [1].To obtain cell walls from the yeast phases of these strains, PGY medium (peptone, 5 g l-I; yeast extract, 5 g l-I; glucose, 15 g 1 -l) was used. Cells were grown for 5-6 days on a gyratory shaker at 37°C. Ceils were collected, and w,alls isolated and fractionated as previously described [5]. Analysis of hexoses, aminoacids, and aminosugars were done as before [5]. Sugars were identified by thin layer chromatography in silica gel, using n-butanol: acetic acid: water (6:3:1, v/v/v) as the solvent and naphthoresorcinol (20 mg) in ethanol (10 ml) and concentrated H2SO, (0-2 ml) as developer.Results are summarized in Table 1. Alkali-insoluble fraction 1High amounts of this fraction were found in all strains. They were composed of variable quantities of hexoses (exclusively as glucose), amino sugars (as glucosamine)