A vaccine and monoclonal antibodies that enhance mouse resistance to Candida albicans vaginal infection

We previously reported that a vaccine composed of liposome-mannan complexes of Candida albicans (L-mann) stimulates mice to produce protective antibod ies against disseminated candidiasis. An immunoglobulin M (IgM) monoclonal antibody (MAb), B6.1, specific for a beta-1,2-mannotriose in the complexes protects against the disease, whereas MAb B6 does not. In the present study , the vaccine and MAbs B6,1 and B6 were tested for the ability to protect a gainst Candida vaginal infection, established by intravaginal (i.vg,) inocu lation of yeast cells in mice maintained in pseudoestrus. Fungal CFU in eac h vagina was determined to assess the severity of infection, Mice vaccinate d before infection developed about 62% fewer vaginal CFU than nonimmunized controls. Naive mice that received polyclonal antiserum (from vaccinated mi ce) i,vg, before infection had 60% fewer CPU than controls, The serum prote ctive factor was stable at 56 degrees C, but C. albicans cells absorbed thi s factor, Mice given MAb B6,1 i,vg, after infection was established had few er Candida CPU in vaginal tissue than control mice given buffer instead of antibody, MAbs B6,1 and B6 given intraperitoneally before infection protect ed mice, but MAbs preabsorbed with yeast cells did not. MAb B6,1 also prote cted against C, tropicalis vaginal infection, but MAb B6 did not, The prote ctive activities of MAbs B6.1 and B6 appeared to be specific because an irr elevant IgM carbohydrate-specific MAb and an irrelevant IgG protein-specifi c MAb were not protective; also, MAb B6,1 did not affect development of vag inal chlamydial infection. These studies show that an appropriate antibody response, or administration of protective antibodies, can help the host to resist Candida vaginal infection.