BoNT/A1 neutralization activity of four purified monoclonal antibodies.

The protective titer is the highest dilution of the purified antibody that allows the neutralization of 5 estimated MLD50 of BoNT/A1 neurotoxin in the mouse protection assay.
Ten-fold dilutions were used to generate final antibody concentrations ranging from 2.21 ng-2.21 µg/mouse for TA12, 700 ng-7 µg for TA17, 5.9 µg for TA9, and 6.1 µg for TA16. These dilutions were incubated with toxin for 30 min and 0.5 ml was injected to give final toxin challenges of approximately 5 MLD50/mouse of a group of 4 for each dilution.
*Lowest amount of antibody needed to completely protect the mice against a 5 estimated MLD50 toxin.