Table 3.

Challenge of Atlantic salmon smolts by i.p. injection (trial 2)a

A. salmonicida strainDay 8LD50 (CFU) on day 15b
ED50 (CFU)+95% CI (CFU)−95% CI (CFU)
MT13262.63 × 1032.01 × 1041.42 × 102<102
MT1326ΔG1.08 × 1038.18 × 1032.64 × 101<102
MT1326ΔSP4.55 × 1037.13 × 1043.49 × 1016.25 × 102
  • a Groups of six fish were injected with each dose (ranging from 108 to 102 CFU) of the parent or respective mutants of A. salmonicida MT1326 or PBS, as described in Materials and Methods, and monitored for 15 days. There were no deaths among PBS controls.

  • b <102, LD50 lower than the lowest dose tested (102 CFU). The lower estimated 95% confidence interval (CI) for MT1326ΔSP was below zero; therefore, no valid statistical comparison to the parent strain can be made.