φb0847 harbors multiple loci that contribute to the fitness of CFT073 during systemic challenge.
(A) Equal numbers (1,000–2,000 CFU total) of wild type CFT073 and each mutant derivative indicated were inoculated into the bloodstream of embryos. Fish were sacrificed and bacterial loads enumerated at 12 hours post inoculation (hpi) by differential plating (n>28). Data are presented as competitive indices with negative values indicating a reduction in fitness of the mutant. P values were determined using two-tailed Mann-Whitney t tests; bars indicate median values. (B), (C), and (D) 1,000–2,000 CFU of wild type CFT073, the indicated mutant, or recombinant derivative were each inoculated into the blood of 48 hpf embryos. Fish were scored for death every 6 h starting at 18 hpi until 48 hpi (n = 40 or more embryos for each curve). pGEN-mcs in (D) serves as an empty vector control for pGEN-neaTPnative. Data in (B), (C), and (D) are presented as Kaplan-Meier survival plots. A log-rank (Mantel-Cox) test was used to determine p values; ns = not significant.