Immunogenicity and protective effect of recombinant enolase of Candida albicans in a murine model of systemic candidiasis.

Enolase, a 46-kDa glycolytic enzyme, is an immunodominant antigen of the opportunistic pathogen Candida albicans. A recombinant 6 x His-tagged enolase was studied, in conjunction with interleukin-12 (IL-12), as an adjuvant for cytokine induction favouring protection in a murine model of haematogenous candidiasis. Mice immunized with enolase plus IL-12 showed increased antibody titres against enolase, as well as increased median survival time and decreased fungal burden in kidneys, in comparison to non-immunized or IL-12-treated mice. This increased survival was attributable to enolase-induced cell-mediated immunity as it also occurred in B-cell-deficient mice. Enolase immunization stimulated a predominant T-helper-1 (Th1) cytokine pattern in splenic cells and induced production of interferon-gamma (IFN-gamma) and interleukin-2 (IL-2) by purified CD4+ T cells. However, despite the elevation of immunogenicity, recombinant enolase induced only a modest protection against disseminated candidiasis, suggesting a form of protection likely attributable to the induction of a Th1 cell-mediated immune response.