Characterization of Candida albicans antigenic determinants by two-dimensional polyacrylamide gel electrophoresis and enhanced chemiluminescence.

The use of a two-dimensional polyacrylamide gel electrophoresis joined with Western blotting allowed us to investigate the reactivities of antibodies present in sera from mice and humans to antigens of Candida albicans blastoconidia. The analysis of the antibody response in the two models studied and the comparison between the antibody response in infected and noninfected individuals showed that the infection by C. albicans produces changes in the antibody response which may be of relevance in the serodiagnosis of invasive candidiasis. These changes include the induction of antibodies against new antigens, the disappearance of antibodies against a group of antigens and variations in the reactivity of antibodies directed to a different group of antigens. The technique used resolved the isoforms of several antigens including enolase. It is concluded that the antibody response in humans and mice with candidiasis is not homogeneously directed to all the isoforms of an antigen.

Re-expression by Candida albicans germ tubes of antigens lost during subculture of blastospores.

The effect of germ tube induction on the antigenic variability in C.albicans was studied in strains from blood cultures (Group I) and superficial candidiasis (Group II). When compared by immunoblotting with a rabbit antiserum, antigenic extracts from Group I strains grown as blastospores showed a higher reactivity than that of Group II strains. Major bands in Group I strains (45-47, 33, 30 kDa) were continuously expressed through the subcultures in vitro but, with the exception of the 45 kDa band, the reactivity of all of them decreased or disappeared after the tenth subculture in Group II strains. The induction of the germ tubes produced the re-expression of the antigens lost during subculture in the yeast form, the effect being very clear in Group II strains. The re-expression by C. albicans germ tubes of antigens lost during subculture of blastospores in vitro and the higher reactivity shown by Group I strains grown in mycelial phase should be taken into consideration when a test to detect anti-C. albicans antibodies is to be developed.

Candida albicans stress mannoproteins expression in superficial and systemic candidiasis. Stress mannoproteins in Candida albicans.

The presence of heat shock mannoproteins (HSMPs) reactive with sIgA was demonstrated in several C. albicans strains. The subculture of the C. albicans isolated from mucosal surfaces on Sabouraud's dextrose agar at 25 degrees C switched off the HSMP expression. A re-expression of the HSMPs was obtained in the same medium by shifting the temperature of incubation to 37 degrees C. However, expression of HSMPs in two strains isolated from deep infections was maintained during several subcultures on Sabouraud's dextrose agar at 25 degrees C. A glycoprotein of 200 kDa seemed to be the main HSMP reacting with vaginal sIgA. The data presented in this study suggest that factors other than temperature can influence the expression of C. albicans HSMPs and therefore these antigens should be referred as stress mannoproteins.

Heat-shock mannoproteins as targets of secretory IgA in Candida albicans.

The expression of Candida albicans antigenic determinants reacting with secretory IgA from patients with oral and vaginal candidiasis was investigated under different in vitro conditions. Reversible antigenic transitions were inducible in synthetic medium by temperature shifts, as the yeast cells were positive by an indirect immunofluorescence assay after being incubated at 37 degrees C but not at 25 degrees C. In vitro temperature-inducible C. albicans antigenic determinants reactive with secretory IgA were characterized by radioimmune Western blot as mannoproteins with molecular masses of 180-200, 130-150, 90-110, and 60-70 kDa. This is the first report on the expression of mannoproteins regulated by temperature involved in the secretory immune response during mucosal candidiasis.