BoNT/A1 neutralization activity of crude ascite fluids from 14 mAbs in the mouse protection assay (5 estimated MLD₅₀/mouse).

The protective titer is the highest dilution of the ascitic fluid that completely protected against 5 estimated MLD50 of BoNT/A1 in the mouse protection assay. Underline: non-neutralizing antibodies. Three ml of 10 estimated MLD50/ml BoNT/A1 were incubated with 30 µl of serial ten-fold dilutions of ascitic fluid for 30 min at room temperature. 500 µl of the mixtures were injected intraperitoneally to give final toxin challenges of approximately 5 MLD/50 into each mouse of a group of 4 for each dilution.