Table 1.
Potential virulence genes of the Shewanella oncorhynchi strains
| Function | Gene | K61 | K313 | K999 |
|---|---|---|---|---|
| Flagella protein | flgI flmH fleN/flhG motA fliG fliM fliP flhA cheW cheY | + | + | + |
| cheV | + | |||
| lfgG | + | + | ||
| Type IV pilus protein | tapC tapT tufA mshG | + | + | + |
| tapB | + | |||
| Heat-shock protein | htpB | + | + | + |
| T2 secretion system | exeF | + | ||
| epsE epsG | + | + | + | |
| T3 secretion system | vscC2 vscN2 vscR2 vscS2 vscU2 | + | + | |
| Ferric-siderophore adenosine | bauB | + | ||
| 5′-triphosphate binding cassette transporter | bauD | + | + | + |
| Immune modulation | galE pseC rpoS lpxC kdsA | + | + | + |
| rfbC rffG | + | |||
| ugd pseI | + | |||
| wbtL ACICU cap8E | + | |||
| Regulation | rpe tufA csrA fur | + | + | + |
| Stress survival | katA clpP sodB | + | + | + |
| Biofilm | adeG algU luxS | + | + | + |
| Putative carbonic anhydrase | mig-5 | + |
Fig. 1.
Lesions observed in common carp challenged with Shewanella oncorhynchi: group A (bacterium strain K999) – swollen abdomens, discolorations of the skin, lens opacity and swelling of the kidneys; group B (strain K313) – slightly swollen abdomens, discolorations of the skin, lens opacity and swelling of the kidneys; group C (strain K61) – slightly swollen abdomens, lens opacity, swelling of the kidneys, skin lesions and discolorations; group K – no lesions
Fig. 2.
Cumulative mortality in fish infected with K999, K313 and K61 strains and in uninfected fish
Fig. 3.
Cytotoxicity of Shewanella oncorhynchi to common carp epithelial cells: A – Percent of cytotoxicity of K999, K313 and K61 strains after 48 h incubation; B1 – Photomicrograph (×100) of carp epithelial cells uninfected with any strain of S. oncorhynchi (control groups cells); B2 – Photomicrograph (×100) of carp epithelial cells infected with K999 strain. Experiment I – initial 48-h experiment; Experiment II – first independent repeat; Experiment III – second independent repeat