FIG 8.

Analysis of virulence of wild-type and ΔgldN mutant cells toward rainbow trout following challenge by injection. Kaplan-Meier survival curves of rainbow trout after intramuscular injection challenge. Four groups of 20 fish (n = 80) were challenged with each F. psychrophilum strain at doses (CFU/fish) of 2.6 × 10⁶ for the wild type, 2.7 × 10⁶ for the ΔgldN mutant, and 2.8 × 10⁶ for the ΔgldN mutant complemented with pBFp4. Survival curves for fish inoculated with PBS (Control) and for fish inoculated with the ΔgldN mutant were identical. Survival curves for fish inoculated with either the wild type or the ΔgldN mutant complemented with pBFp4 are significantly different from survival curves for the ΔgldN mutant (Mantel-Cox log rank test, P < 0.0001). The survival curve of the ΔgldN mutant complemented with pBFp4 was modestly higher than that of the wild type (P = 0.0012).