Increased resistance in BALB/c mice to reinfection with Candida albicans is due to immunoneutralization of a virulence-associated immunomodulatory protein.

Here, it is shown that immunoneutralization of p43, a virulence-associated immunomodulatory protein secreted by Candida albicans, is responsible for immunoprotection against candidiasis after spontaneous healing of mice inoculated with 10(6) C. albicans blastoconidia. p43 is produced by the pathogenic Candida blastoconidia, and neither immunoprotection nor immunoneutralization can be elicited by priming the mice with attenuated or heat-killed C. albicans blastoconidia. The immunoprotection against systemic candidiasis was positively correlated with (i). serum levels of antibodies against p43 and (ii). a high ratio between antibodies against p43 and antibodies against C. albicans structural antigens. Immunoprotection against candidiasis can be induced in mice primed with heat-killed C. albicans, after treatment of the animals with anti-p43 antibodies. The data described here provide a biological explanation for active immunoprotection achieved after spontaneous healing of infectious diseases, namely in candidiasis.