Production and characterization of monoclonal antibodies against the hemolysin BL enterotoxin complex produced by Bacillus cereus

A total of five hybridoma cell lines that produced monoclonal antibodies ag ainst the components of the hemolysin BL (HBL) enterotoxin complex and sphi ngomyelinase produced by Bacillus cereus were established and characterized , Monoclonal antibody 2A3 was specific for the B component, antibodies 1A12 and 8B12 were specific for the L-2 component, and antibody 1C2 was specifi c for the L-1 protein of the HBL enterotoxin complex. No cross-reactivity w ith other proteins produced by different strains of B. cereus was observed for monoclonal antibodies 2A3, 1A12, and 8B12, whereas antibody 1C2 cross-r eacted with an uncharacterized protein of approximately 93 kDa and with a 3 9-kDa protein, which possibly represents one component of the nonhemolytic enterotoxin complex. Antibody 2A12 finally showed a distinct reactivity wit h B. cereus sphingomyelinase; The monoclonal antibodies developed in this s tudy were also successfully applied in indirect enzyme immunoassays for the characterization of the enterotoxic activity of B. cereus strains. About 5 0% of the strains tested were capable of producing the HBL enterotoxin comp lex, and it could be demonstrated that all strains producing HBL were also highly cytotoxic.