We sought to define protective mechanisms of immunity to Staphylococcus aureus and Candida albicans bloodstream infections in mice immunized with the recombinant N-terminus of Als3p (rAls3p-N) vaccine plus aluminum hydroxide (Al(OH3) adjuvant, or adjuvant controls. Deficiency of IFN-γ but not IL-17A enhanced susceptibility of control mice to both infections. However, vaccine-induced protective immunity against both infections required CD4+ T-cell-derived IFN-γ and IL-17A, and functional phagocytic effectors. Vaccination primed Th1, Th17, and Th1/17 lymphocytes, which produced pro-inflammatory cytokines that enhanced phagocytic killing of both organisms. Vaccinated, infected mice had increased IFN-γ, IL-17, and KC, increased neutrophil influx, and decreased organism burden in tissues. In summary, rAls3p-N vaccination induced a Th1/Th17 response, resulting in recruitment and activation of phagocytes at sites of infection, and more effective clearance of S. aureus and C. albicans from tissues. Thus, vaccine-mediated adaptive immunity can protect against both infections by targeting microbes for destruction by innate effectors.

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We have shown that vaccination with the recombinant N terminus of Als1p (rAls1p-N) protects mice against disseminated and oropharyngeal candidiasis. We now report that vaccination of mice with a related candidate, rAls3p-N, induces a broader antibody response than rAls1p-N and a similar cell-mediated immune response. The rAls3p-N vaccine was equally as effective as rAls1p-N against disseminated candidiasis but was more effective than rAls1p-N against oropharyngeal or vaginal candidiasis. Antibody titers did not correlate with protection against disseminated candidiasis, but delayed-type hypersensitivity did. The rAls3p-N vaccine is a promising new vaccine candidate for further exploration to prevent systemic and mucosal candidal infections.

We previously reported that vaccination with Freund's adjuvant plus the recombinant N-terminus of the candidal adhesin, Als3p (rAls3p-N), protects mice from disseminated candidiasis. Here we report that the rAls3p-N vaccine is effective when combined with aluminum hydroxide adjuvant. Antibody titers of > or =1:6400 accurately predicted protection from infection. Nevertheless, neither B lymphocytes nor serum from immunized animals transferred protection to vaccine-naive animals. In contrast, CD3(+), CD4(+), or CD8(+) T lymphocytes from immunized animals transferred protection, and the vaccine was efficacious in IL-4-deficient mice but not in IFN-gamma-deficient mice. These data have significant implications for the development and interpretation of vaccine surrogate markers.

Candida spp. are the third most common nosocomial bloodstream isolates (15), exceeded in frequency only by coagulasenegative staphylococci and Staphylococcus aureus. Disseminated candidiasis has an attributable mortality of 40 to 50%, even with modern antifungal therapy (3,7,8,14). Clearly, new strategies to prevent Candida infections are needed.Disseminated candidiasis typically occurs after multiple weeks of hospitalization (15), affording the opportunity to intervene prior to disease onset. Furthermore, the major clinical risk factors for developing disseminated candidiasis have been well described (12), facilitating identification of at-risk patients prior to disease onset. Therefore, vaccination of targeted patient populations is an ideal strategy to prevent or ameliorate this life-threatening infection.We have developed a vaccine based on an adhesin from C. albicans. Immunization with the recombinant N-terminal domain of Als1p (rAls1p-N) resulted in a marked improvement in survival of both immunocompetent and immunocompromised mice infected via the tail vein with an otherwise lethal inoculum of C. albicans (6, 13). We have recently reported that the mice in our murine model of hematogenously disseminated candidiasis die of septic shock (11). As candidal sepsis in humans is associated with mortality rates in excess of 55% despite antifungal therapy (9, 12), the rAls1p-N-induced survival rate of Ն50% in this model, without adjunctive antifungal therapy, is highly encouraging.All of the in vivo rAls1p-N vaccine experiments to date have been performed in BALB/c mice, have utilized Freund's adjuvant, and have utilized a single, virulent strain of C. albicans. The current studies were performed to define the breadth of protection induced by rAls1p-N by specifically evaluating its efficacy in outbred mice, in combination with a second adjuvant, against other strains of C. albicans, and against non-C. albicans species of Candida. rAls1p-N improved the survival of outbred mice from disseminated candidiasis. Outbred CD1 mice were obtained from the National Cancer Institute (Bethesda, MD). All procedures involving mice were approved by the institutional animal use and care committee, following the National Institutes of Health guidelines for animal housing and care. The mice were vaccinated with rAls1p-N plus Freund's adjuvant as previously described (6, 13). Briefly, rAls1p-N (amino acids 17 to 432 of Als1p) was produced in Saccharomyces cerevisiae and purified by gel filtration and Ninitrilotriacetic acid matrix affinity purification. A high degree of purity (ϳ90%) was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis as well as circular dichroism and Fourier transform infrared microscopy, as described previously (10). Mice were immunized by subcutaneous injection of rAls1p-N (20 g) mixed with complete Freund's adjuvant (CFA; Sigma-Aldrich, St. Louis, MO) at day 0, followed by a booster dose in incomplete Freund's adjuvant (IFA; Sigma-Aldrich) at day 21. Control mice were immunized with CFA fol...

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These studies demonstrate a dissociation between survival and tissue fungal burden during murine fusariosis. Although prophylactic LAmB may be useful at reducing tissue fungal burden, polyenes had limited survival benefit for active fusariosis. Caspofungin at 1 but not 5 mg/kg/day mediated surprising improvements in survival during active fusariosis, despite lack of reduction in fungal burden. Further studies are warranted.