RATS CLEARING A VAGINAL INFECTION BY CANDIDA-ALBICANS ACQUIRE SPECIFIC, ANTIBODY-MEDIATED RESISTANCE TO VAGINAL REINFECTION

Oophorectomized, estrogen-treated rats were susceptible to experimenta l vaginal infection by Candida albicans. After spontaneous clearing of the primary infection, the animals were highly resistant to a second vaginal challenge with the fungus. The vaginal fluid of Candida-resist ant rats contained antibodies directed against mannan constituents and secretory aspartyl proteinase(s) of C. albicans and was capable of tr ansferring a degree of anti-Candida protection to naive, nonimmunized rats, This passive protection was mediated by the immunoglobulin fract ion of the vaginal fluid and was substantially abolished by preabsorpt ion of the vaginal fluid with C. albicans, but not with Saccharomyces cerevisiae, cells. Vaginal anti-mannan antibodies were also produced b y active immunization with heat-killed cells of C. albicans or with a mannan extract when administered via the vaginal route. The protection conferred was comparable to that resulting from clearing of the prima ry infection. In summary, the data suggest that acquired anticandidal protection in this vaginitis model is mediated at least in part by ant ibodies, among which those directed against the mannan antigen(s) migh t play a dominant role.