Table 2.
Results obtained in the in vivo and ex vivo virulence assays performed with the new isolates in comparison with those of the control strains.
| Resistance to a | Virulence forb | ||||
|---|---|---|---|---|---|
| Tilapia | Mouse | ||||
| Strain | TP | HS + Fe | i.p. injection | Immersion | i.p. injection |
| Tilapia isolates | |||||
| VV3 | + (9.1 × 103%) | + (7.0 × 102%) | + (3.3 × 106) | + (3.3 × 105) | + (1.5 × 106) |
| VV4 | + (8.3 × 103%) | + (1.1 × 103%) | + (8.4 × 105) | + (8.4 × 105) | + (9.2 x 105) |
| VV5 | + (8.5 × 102%) | + (3.1 × 103%) | + (2.5 × 106) | + (4.2 × 105) | + (2.0 × 106) |
| TI417 | + (9.5 × 102%) | + (1.7 × 103%) | NT | + (1.0 × 106) | NT |
| Control strains | |||||
| CECT 4999 | + (8.5 × 102%) | + (1.9 × 103%) | - (> 107) | - (> 108) | + (1.0 × 106) |
| YJ016 | -(0%) | + (4.9 × 103%) | - (> 107) | - (> 108) | + (1.0 × 106) |
| CECT 529T | -(0%) | + (5 × 102%) | - (> 107) | - (> 108) | - (> 107) |
a
Resistance to tilapia plasma (TP) and iron-overloaded human serum (HS+ 10 μM of FeCl3 [13]) after 4 h at 28°C (tilapia) or 6 h at 37°C (human) is coded as follow: +, survival ≥100%; -, survival <100%. Data in parentheses correspond to the medium percent survival from three independent experiments.
b
The medium value of 50% lethal dose (LD50) from two different experiments is presented in parentheses as cfu/g (i.p. injection) or /ml (inmersion). Results are coded as follows: fish and mouse injection; - (≥107), + (< 107); fish immersion; - (≥108) + (< 108) [10, 24].
NT, not tested.