IDIOTYPIC INTRAVAGINAL VACCINATION TO PROTECT AGAINST CANDIDAL VAGINITIS BY SECRETORY, YEAST KILLER TOXIN-LIKE ANTIIDIOTYPIC ANTIBODIES

The principles of idiotypic (Id) vaccination were used to immunize aga inst vaginitis caused by Candida albicans, a widespread and sometimes intractable disease in women. To this aim, a murine mAb (KT4, IgG1) ne utralizing in vitro the anti-Candida activity of a yeast killer toxin (YKT) was used as an id vaccine to elicit Abs with toxin-like activity in a rat vaginitis model. Nonimmunized and isotype-matched, irrelevan t mAb-immunized rats served as controls. An effective protection was o btained in Id-vaccinated animals, as demonstrated by a highly signific ant decrease in vaginal Candida CFU compared with controls. The protec tion was associated with rising vaginal titers of anti-idiotypic Abs ( IdAb), prevalently of the IgA isotype, that were able to passively tra nsfer the protective state to nonimmunized animals. The vaginal IdAb p ossessed YKT-like activity because they were able to kill in vitro the challenging fungal cells, and this killing was neutralized by the mAb KT4. Overall, these data demonstrate that secretory IdAb elicited by intravaginal Id vaccination with mAb KT4 protected the rats from the i nfectious challenge with Candida albicans by molecular mimicking YKT a ctivity as its internal image.