Considerable differences in vaccine immunogenicities and efficacies related to the diluent used for aluminum hydroxide adjuvant

Abstract

We are developing an anticandidal vaccine using the recombinant N terminus of Als3p (rAls3p-N). We report that although more rAls3p-N was bound by aluminum hydroxide diluted in saline than by aluminum hydroxide diluted in phosphate-buffered saline (PBS), its immunogenicity and efficacy were superior in PBS. Thus, protein binding, by itself, may not predict the efficacy of some vaccines with aluminum adjuvants.

FIG. 1.

Immunogenicity of S-3 versus that of P-3. (A) Frequency of Th1/Th2 lymphocytes among ex vivo-stimulated splenocytes from BALB/c mice (eight mice per group) vaccinated with S-A, S-3, P-A, or P-3. Three weeks after the vaccination, the splenocytes were harvested and stimulated for 4 days with rAls3p-N or tetanus toxoid (TT). Medians and interquartile ranges are shown. *, P was ≤0.05 versus all other groups. (B) Culture supernatant cytokines induced by rAls3p-N stimulation of the splenocytes from the vaccinated or control mice. **, P was ≤0.03 versus all other groups; *, P was ≤0.05 versus S-A or P-A controls; †, P was 0.08 versus S-A.

FIG. 2.

Antibody titers and efficacy of the vaccine in the presence of saline versus in the presence of PBS. (A) Serum immunoglobulin G (IgG) anti-rAls3p-N titers were determined by enzyme-linked immunosorbent assay 1, 2, and 3 weeks after vaccination of BALB/c mice with S-A, S-3, P-A, or P-3 (eight mice per group). Medians and interquartile ranges are shown. *, P was <0.05 versus the adjuvant control by the Mann-Whitney U test; **, P was <0.05 versus the adjuvant control by the Mann-Whitney U test and versus week 1 titers by the signed-rank test. (B) Three weeks after vaccination, mice were infected via the tail vein with 2.7 × 10⁵ blastospores of C. albicans SC5314. *, P was <0.04 versus both P-A and S-3.