[Production of monoclonal antibodies. Scorpion antitoxins: characterization and molecular mechanisms of neutralization].

Two monoclonal antibodies specific for the potent toxin II of the scorpion Androctonus australis Hector have been produced. One of them shows both high affinity binding to the toxin (Kd = 0.8 nM) and in vivo and in vitro neutralizing properties. The mechanism by which the antibody neutralizes toxin binding to its receptor was shown to be of the competitive type, the epitope is overlapping or being close to the receptor binding region of the toxin. Several residues of the toxin clustered in the C-terminal region were shown likely to be part of the discontinuous epitope recognized by the antibody. The positive charge of the NH2-Lys58 seems to play a pivotal role in the binding of the toxin to both the monoclonal antibody and the sodium channel receptor.