TABLE 3.
MLD50 assay resultsa
| Toxin concn (pg/ml) | Toxin dilution | Mouse mortality at 96 h (no. of mice that died/total) |
|---|---|---|
| 162.5 | 5 × 10−7 | 3/4 |
| 81.25 | 2.5 × 10−7 | 4/4 |
| 40.62 | 1.23 × 10−7 | 3/4 |
| 20.31 | 6.25 × 10−8 | 4/4 |
| 10.16 | 3.125 × 10−8 | 4/4 |
| 5.08 | 1.56 × 10−8 | 3/4 |
| 2.54 | 7.81 × 10−9 | 0/4 |
Evaluation of mouse mortality 4 days postinjection after intraperitoneal injection of successive dilutions of a BoNT/A (150 kDa) stock solution. Based on the toxin concentration evaluated by gel electrophoresis, the toxin concentration corresponding to each toxin dilution is also indicated. From the mouse mortality observations, the potency of the stock solution can be calculated using the formula 1/LD50 dilution/V (injected volume). If the LD50 is located at a dilution intermediary between 1.56×10−8 and 7.81×10−9, i.e., 1.17×10−8, the potency of the stock solution is 1.7×108 MLD50s/ml. Moreover, the protein concentration corresponding to the MLD50 dilution can be deduced from the data in the first column, i.e., 3.80 pg/ml, which yields an MLD50 value of 1.9 pg (injected volume = 0.5 ml).