TABLE 2.
Adsorption of toxin B by cell wall-displayed VHH fragments
| Strain (VHH fragment) | Protective concn (CFU/ml)a |
|---|---|
| KKA412 (VHH-G1) | 8 × 109 |
| KKA413 (VHH-B2)b | 1 × 109 |
| KKA414 (VHH-D2) | 2 × 109 |
| KKA415 (VHH-E2)b | Not protective |
| KKA416 (VHH-G3)b | 2.5 × 108 |
| KKA417 (VHH-B5)b | 1 × 109 |
| KKA418 (VHH-D8)b | 4 × 109 |
| KKA419 (VHH-G9) | Not protective |
| KKA101 (control) | Not protective |
a
Protective concentration of engineered L. paracasei BL23 displaying anti-toxin B VHH fragments on the cell wall. The bacteria were tested in 2-fold dilutions from 8 × 109 to 1.25 × 108 CFU/ml for adsorption of 5 times the lethal dose of toxin B (50 ng/ml) in the in vitro neutralization assay.
b
The VHH fragment was neutralizing as a soluble monomeric form in the in vitro cell-based assay (Table 1).