Detection of Choristoneura fumiferana brush border membrane-binding molecules specific to Bacillus thuringiensis delta-endotoxin by crossed affinity immunoelectrophoresis.

Brush border membrane vesicles (BBMVs) prepared from midguts of Choristoneura fumiferana larvae were pretreated separately with the three CryIA delta-endotoxins from Bacillus thuringiensis subsp. kurstaki HD-1. Crossed affinity immunoelectrophoresis of the solubilized toxin-BBMV complexes, using antibodies raised against the toxins, revealed at least two peaks for each toxin. All complexes (BBMV bound toxin) migrated in the opposite direction to that of the free toxins. It is concluded that the toxins form stable complexes with membrane acceptor molecules, possibly receptors, and that there are at least two types of acceptor molecules present in the midgut epithelial cells of C. fumiferana that bind to all three toxins. The relative size of one of the BBMV-toxin peaks correlates with the in vivo potency of the toxins against C. fumiferana.