Partial protection against experimental vaginal candidiasis after mucosal vaccination with heat-killed Candida albicans and the mucosal adjuvant LT(R192G)

The effectiveness of a mucosal vaccine composed of heat-killed Candida albicans (HK-CA) or C. albicans culture filtrate (CaCF) in conjunction with the mucosal adjuvant LT(R192G) against vulvovaginal candidiasis was examined in an estrogen-dependent murine model. Mice vaccinated intranasally with HK-CA + LT(R192G) exhibited a significant but short-lived protection accompanied by a vigorous delayed-type hypersensitivity response as well as high titers of circulating C. albicans-specific antibodies. Surprisingly, the levels of antigen-specific antibodies in the vaginal secretions of protected mice were negligible and no correlates of vaginal-associated Type 1 or Type 2 cytokines were observed. Vaginal priming with C. albicans before vaccination did not alter the protective outcome. Immunization with CaCF + LT(R192G) induced a discrete level of protection when administered intrarectally but not intranasally. These results suggest that mucosal vaccination can afford partial protection against vulvovaginal candidiasis, but the precise immune mechanisms responsible for protection are complex and as yet, not well understood.