PRODUCTION AND CHARACTERIZATION OF CROSS-REACTIVE MONOCLONAL-ANTIBODIES TO SWEET PROTEINS

We report on the characterization of a panel of eight murine monoclona l antibodies induced by immunization with the sweet protein monellin a nd which display crossreactivity with thaumatin, another sweet natural molecule. Cross-reactivity was determined based on direct binding ass ays and antigen competition experiments. Interestingly, half of antibo dies bound thaumatin more than monellin, the immunizing antigen. The r elatedness between the binding sites of the eight monoclonal antibodie s was assessed by cross-competition of the binding of monellin to indi vidual monoclonal antibodies. Antibodies that bound in a similar way m onellin and thaumatin were on average the best inhibitors. All antibod ies also bound Spl, a genetically-engineered single chain monellin. Th ese studies demonstrate that the immune repertoire encodes for specifi cities that are common to monellin and thaumatin despite the fact that the two molecules share little, if any, structural homology. These re sults are discussed in relation to the use of cross-reactive antibodie s to generate anti-receptor antibodies via idiotypic immunization.