Production and characterization of monoclonal antibodies against Naja naja atra cobrotoxin

Abstract

B. G. Stiles, B. C. Lidgerding, F. W. Sexton and S. B. Guest. Production and characterization of monoclonal antibodies against Naja naja atra cobrotoxin. Toxicon 29, 1195–1204, 1991.—Twelve monoclonal antibodies against cobrotoxin from Naja naja atra venom were tested for cross-reactivity with eight different snake toxins, binding to linear epitopes, prevention of cobrotoxin binding to acetylcholine receptor (AchR) in vitro, and protection in mice concomitantly given a lethal dose of cobrotoxin. The antibodies were highly specific, as evidenced by little reactivity with other snake toxins. None of the monoclonal antibodies bound to reduced cobrotoxin or synthesized 8-mer regions spanning the whole molecule, thus suggesting the recognition of conformational epitopes. The in vitro binding of toxin to AchR was competitively inhibited (23–79%) with a 1.66 : 1 mole ratio of antibody : AchR. Preincubation of monoclonal antibody with toxin before adding AchR (3 : 1 mole ratio of AchR : antibody) inhibited the in vitro binding of toxin to AchR by 20–80%. Monoclonal antibodies added after the preincubation of toxin with AchR did not dissociate the toxin-AchR complex. An antibody : toxin mole ratio of 2.5 : 1, with 6 μg of cobrotoxin, delayed the time to death of mice 3.7–23.8-fold over control mice. The monoclonal antibodies that most effectively prevented in vitro binding of toxin to AchR also provided the longest delay in time to death in mice.