Table 3.
Mutants of Hcp family genes of T6SS in E. ictaluri.
| BKA | CCO | Stress Assays | Vaccination | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Serum | BLI | Uptake | Survival | Attachment | Invasion | BHI | MM19-P | Virulence | Efficacy | |||||
| SNP | H2O2 | SNP | H2O2 | Fingerling | Fry | Fingerling | Fry | |||||||
| EiΔevpC | – | 14 d | – | + | – | – | – | – | – | – | + | + | + | + |
| EiΔhcp2 | – | 14 d | – | + | + | – | – | – | – | – | + | + | + | + |
| EiΔevpCΔhcp2 | – | 8 d | – | – | + | – | + | + | + | – | + | + | + | + |
Serum, Catfish normal serum treatment at 4 h; BLI, Real-time bioluminescent imaging (persistency of bacteria in 2-weeks); BKA, Bacterial killing assay (peritoneal macrophages), uptake at 0 h and survival at 6 h; CCO, Channel catfish ovary cells (epithelial cells); Stress Assays, Treated with stress factors at 8 h; BHI, Brain-heart infusion broth (rich medium); MM19-P, Low-phosphate minimal medium broth at pH 5.5 (minimal medium); SNP, Sodium nitroprusside (nitrosative stress); H2O2, Hydrogen peroxide (oxidative stress); Virulence, Catfish immersion challenged with mutants and EiWT for 21 days; Efficacy, Catfish immersion re-challenged with EiWT for 21 days; Fingerling, Six-month-old catfish; Fry, Two-week-old catfish. (+) shows difference and (–) shows no difference compared to EiWT (p < 0.05).