The Anti- Candida Vaccine Based on the Recombinant N-Terminal Domain of Als1p Is Broadly Active against Disseminated Candidiasis

Abstract

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...

Considerable Differences in Vaccine Immunogenicities and Efficacies Related to the Diluent Used for Aluminum Hydroxide Adjuvant

“…The vaccine is also effective in combination with Alhydrogel diluted in phosphate-buffered saline (PBS) (8). Vaccine efficacy requires an adjuvant, as the vaccine does not significantly improve survival if no adjuvant is utilized.…”

“…One standard formulation is Alhydrogel, a gelatinous matrix of aluminum hydroxide, which minimizes lot-to-lot variability and enables facile adsorption of proteins (5, 12). As noted by Hem et al, aluminum hydroxide in its dehydrogenated, crystalline form is chemically aluminum oxyhydroxide [AlO(OH)] (7), but in its aqueous phase, it acquires an additional water molecule to become aluminum trihydroxide [Al(OH) 3 ].We have developed a vaccine using the recombinant N terminus of the candidal adhesin Als3p (rAls3p-N), which has been shown to protect mice against otherwise-lethal disseminated candidiasis (8,9,15,16). The vaccine is also effective in combination with Alhydrogel diluted in phosphate-buffered saline (PBS) (8).…”

“…We have developed a vaccine using the recombinant N terminus of the candidal adhesin Als3p (rAls3p-N), which has been shown to protect mice against otherwise-lethal disseminated candidiasis (8,9,15,16). The vaccine is also effective in combination with Alhydrogel diluted in phosphate-buffered saline (PBS) (8).…”

“…Finally, to determine vaccine efficacy, the vaccinated and control mice were infected via the tail vein with Candida albicans SC5314, as we have previously described (8,9,(14)(15)(16)(17). Mice vaccinated with P-3 had significantly improved survival compared to all other groups (Fig.…”

Vaccination with Recombinant Non-transmembrane Domain of Protein Mannosyltransferase 4 Improves Survival during Murine Disseminated Candidiasis

“…[3][4][5][6] These candidate vaccines may be useful in preventing systemic candidiasis in some categories of at-risk subjects before they become heavily immunocompromised. [7][8][9][10][11] Humoral immunity provides substantial protection against C. albicans growth. [12][13][14][15] Cellular immunity against systemic candidiasis is important as well.…”