<i>Saccharomyces</i>as a Vaccine Against Systemic Candidiasis

Abstract

We have shown heat-killed Saccharomyces (HKY) is a protective vaccine against aspergillosis and coccidioidomycosis. To test the hypothesis that the efficacy of HKY- induced protection may be due to the cross-reactive antigens in the cell walls of the different fungi, we studied the effect of HKY against systemic candidiasis. Male CD-1 mice were given different regimens of HKY subcutaneously prior to intravenous challenge with Candida albicans. Compared to PBS controls, the administration of HKY (6 × 10(7)) 3, 4 or 6 times prolonged survival (all P < 0.05) and reduced fungal load in the kidney (all P < 0.05). An HKY dose of 1.2 × 10(8) given 4 times prolonged survival (P = 0.02), but showed dose-limiting toxicity. HKY given by an oral route, or by a subcutaneous route with alum as an adjuvant, did not improve survival. Overall, we found that HKY protects mice from infection by Candida albicans in a dose-and regimen-dependent manner. To understand the protection induced by HKY against different fungal species, additional studies of epitope mapping are warranted.