Production and characterization of three monoclonal antibodies to Candida albicans proteins

Three monoclonal antibodies, designated A2C7, C2C7, and F19, were produced which recognize proteins from Candida albicans. All are of the immunoglobulin G1 heavy chain and kappa light chain class. A2C7 and C2C7 immunoprecipitated three proteins contained in a partially purified fraction (region A) of a mycelial cytoplasmic extract of C. albicans. The apparent molecular weights of these proteins are 120,000 (120K) to 135K, 44K to 52K, to 38K. Monoclonal antibody F19 was reactive with proteins of 42K, 43K, and 50K in immunoblotting experiments. F19 was also able to form a precipitin band in agarose gel with protein(s) contained in region A. Limited proteolytic digestion of the three proteins immunoprecipitated by A2C7 and C2C7 demonstrated that both monoclonal antibodies recognized the same three Candida proteins and that there exists a significant degree of relatedness in primary structure among the three proteins. Proteins with apparent molecular weights of 120K to 135K, 44K to 52K, and 35K to 38K that were immunoprecipitated by sera from two patients with invasive candidiasis and by the serum from a rabbit immunized against a 48K (44K to 52K) Candida protein were also analyzed by limited proteolysis. Patterns of peptide fragments generated by enzymatic digestion of these proteins showed that the proteins recognized by the monoclonal antibodies are the same proteins recognized by antibodies in the sera of patients during an invasive Candida infection and by antibodies in the serum of the immune rabbit.