Contribution of the antibodies response induced by a low virulent Candida albicans strain in protection against systemic candidiasis

A low virulent Candida albicans mutant, CNC13, deleted in the Mitogen Activated Protein (MAP) kynase HOG1 was used to immunize BALB/c mice. Hog1p is essential for the oxidative stress and hyperosmolarity responses. Several doses and immunization procedures were employed. The protection capacity of the different sera generated was analyzed in a murine model of systemic candidiasis. Using a proteomic approach (two-dimensional gel electrophoresis followed by Western blotting), we were able to distinguish two categories of serum: protective and nonprotective, which showed different titres of total Immunoglobulins (Igs) and IgG2a (analyzed by enzyme-linked immunosorbent assay). The levels of Igs and IgG2a in protective sera were significantly higher compared to nonprotective sera. The pattern of a "nonprotective" profile was composed of enolase (Eno1p), transketolase, heat shock protein and methionine synthase. Only antibodies against enolase are the IgG2a isotype. The pattern of a "protective" sera, on the other hand, was composed of antibodies against the following antigens: several isoforms of Eno1p, pyruvate decarboxylase, pyruvate kynase, a protein of the 40S ribosomal subunit, triosephosphate isomerase, DL-glycerol phosphatase and fructose-bisphosphate aldolase. All these antibodies are the IgG2a isotype. The proteins described in the protective sera might be useful for future vaccine development.