TABLE 4.
Virulence of V. anguillarum wild-type strains M93Sm and NB10 and empA mutants M99 and NB12 in Atlantic salmon by AIBa
| Strain | Dose/fish (CFU) | Mortality (no. dead/no. intubated) | Day of death (no. dead/no. intubated) |
|---|---|---|---|
| M93Sm | 9.15 × 105 | 3/5 | 5 (1/5), 10 (3/5) |
| 7.15 × 106 | 4/5 | 2 (1/5), 6 (2/5), 9 (3/5), 11 (4/5) | |
| 2.77 × 107 | 5/5 | 2 (2/5), 3 (3/5), 4 (4/5), 6 (5/5) | |
| NB10 | 1.42 × 106 | 4/5 | 3 (1/5), 5 (2/5), 10 (3/5), 11 (4/5) |
| 6.50 × 106 | 5/5 | 2 (2/5), 5 (3/5), 8 (4/5), 10 (5/5) | |
| 5.35 × 107 | 5/5 | 2 (1/5), 7 (2/5), 8 (3/5), 9 (5/5) | |
| M99 | 9.50 × 105 | 1/5 | 2 (1/5) |
| 3.47 × 106 | 1/5 | 2 (1/5) | |
| 1.04 × 107 | 2/5 | 4 (1/5), 6 (2/5) | |
| NB12 | 1.68 × 106 | 0/5 | NAb |
| 1.04 × 107 | 0/5 | NA | |
| 8.15 × 107 | 0/5 | NA | |
| Control (NSS) | 0/15 | NA |
a
Fish were anally intubated with 50 μl of washed cells suspended in NSS (experimental) or NSS alone (control) at the indicated dosage amount. A small amount of phenol red was added to the cell suspension to ensure there was no leakage. The experiment continued for 21 days. Death due to vibriosis was confirmed by observing clinical signs and isolation of streptomycin-resistant V. anguillarum cells.
b
NA, not applicable: no death due to vibriosis during the 21-day experiment.