TABLE 2.

Association of BT2 plasmids with bacterial virulence in eels and mice and growth in eel and human sera and whole blood

StrainPlasmid contentLD50 ina:Fold growth (mean ± SD)b in:
EelMouseEel bloodHuman blood
WholeSerumWholeSerum
CECT4999pR994.1 × 1027.0 × 10470.00 ± 2.0081.10 ± 1.601.30 ± 0.100.20 ± 0.03
CT218None>1.0 × 107c4.3 × 1050.70 ± 0.10c0.03 ± 0.02c0.80 ± 0.100.18 ± 0.02
CT223pC4602-1>1.0 × 106cNDeND0.01 ± 0.00cNDND
CT225pC4602-1 and pC4602-23.1 × 104dNDND82.50 ± 0.70NDND
CT226pC4602-1 and pC4602-26.3 × 104dNDND79.10 ± 2.60NDND
CT227pC4602-22.3 × 104dNDND83.50 ± 0.60NDND
YJ016pYJ016>1.0 × 107c3.7 × 105ND<0.01c1.30 ± 0.150.21 ± 0.03
  • a Expressed as CFU per fish or mouse.

  • b Bacterial growth after 4 h of incubation with respect to the inoculated dose (n = 3).

  • c Significant difference from strain CECT4999 (P < 0.005).

  • d The LD50 decreased to around 102 CFU per fish after one passage through the eels.

  • e ND, not done.