Table 2.
TcdA neutralizing potency and efficacy of VHH constructs.
| Antibody | Linker | TcdA inhibition | ||
|---|---|---|---|---|
| IC50 (nM) | IC99 (nM)a | Efficacy (%)b | ||
| A20 | na | – | – | – |
| A26 | na | 52.6 ± 3.2 | 719 | 88.1 ± 1.7 |
| A20-A20 | [GS]6 | 174.5 ± 12.5 | 2,123 | 84.9 ± 2.4 |
| A26-A26 | [GS]6 | 39.0 ± 2.9 | 1,189 | 89.1 ± 2.1 |
| A20-A26 | [GS]6 | 0.16 ± 0.01 | 0.27 | 93.8 ± 1.0 |
| A26-A20 | [GS]6 | 49.7 ± 9.1 | 7,866 | 85.3 ± 4.2 |
| CDA1 IgG | na | 30.0 ± 8.1 | 3,342 | 77.5 ± 6.2 |
| A20-A26 (G4S) | [G4S] | 0.22 ± 0.02 | 0.54 | 85.1 ± 1.2 |
| A20-A26 (G4S)2 | [G4S]2 | 0.23 ± 0.02 | 0.42 | 87.7 ± 1.1 |
| A20-A26 (G4S)3 | [G4S]3 | 0.29 ± 0.02 | 0.46 | 93.5 ± 0.8 |
Vero cell cytotoxicity assays measuring mean ± SD TcdA inhibition after 72 h, from three technical replicates, shown in Figures 3B,C. na, not applicable; −, lack of neutralization activity (at 100 nM VHH concentration). aCalculated from mean IC50 value and Hill slope. bMaximum level of TcdA inhibition.