Expression of the complement-binding protein (MP60) of Candida albicans inexperimental vaginitis

The expression of the Candida albicans complement-binding C3d protein (MP60 ) was investigated both in vitro and in vivo by immunogold labelling and el ectron microscopy. In vivo expression was determined in a rat vaginitis mod el. Reactivity of in vitro-grown cells to an anti-MP60 rabbit serum was ass ociated with both cytoplasmic and cell wall sites. Immunostaining in the ce ll wall of both yeast and hyphae was most concentrated in the inner, electr on-lucid layer. Immunogold stained preparations of C. albicans from vaginal smears of infected animals also showed intense localization of the MP60 in the inner cell wall, plasma membrane. However, immunogold label was also i ntense at the cell surface in these samples, mostly in the area of close ad herence with the keratinocytes of the vaginal epithelia. These observations indicate that MP60 is expressed both in vitro and in vivo, but to a differ ent degree in the different cell wall layers.