Figures & data
Figure 1. Construction and phenotypic characterization of the Δahn mutant and the complement strain, CΔahn. (A) Strategy for the deletion of ahn by homologous recombination. (B) Growth curves of the WT, Δahn and CΔahn strains. (C) β-Hemolytic phenotype of the strains grown on sheep's blood agar. (D) Scanning electron microscopic pictures of different strains (scale bar = 1 μm).
Figure 2. Effect of Ahn deletion as determined by bactericidal assays. (A) Percentage of CFUs following 1 h of incubation with head-kidney macrophages. (B) Percentage of CFUs following 1 h of incubation at 37°C with heparinized mouse blood. The experiments were performed 3 times independently. The data shown were obtained from a representative experiment. *P < 0.05.
Figure 3. Role of Ahn in resistance against clearance in vivo. (A) Severe accumulation of ascites in the abdomen of a blunt snout bream (Megalobrama amblycephala) infected with A. hydrophila. Scale bar = 1 cm. (B) Bacterial loads recovered from fish ascites after 24 h post-i.p. inoculation. (C) In vivo competitive indices of Δahn versus the WT strain in fish abdominal cavity and mouse air sac infection models.
Figure 4. Inactivation of ahn impairs A. hydrophila systemic dissemination. (A) Numbers of viable A. hydrophila bacteria in mouse blood at 24 h after i.p.inoculation. Numbers of viable A. hydrophila bacteria in fish kidneies (B) and livers (C) at 24 h after i.p. inoculation. (D) Pathological examination of kidneies of fish infected with the indicated A. hydrophila strains. The arrow indicates renal tubular cell swelling. Scale bar = 200 μm.
Figure 5. Ahn contributes to the virulence of A. hydrophila. (A) Survival curves for fish challenged with A. hydrophila wild-type and deletion strains. (B) Survival curves for mice challenged with A. hydrophila.
Table 1. Primers used in this study
Table 2. Calculations of the LD50 values of the WT and Δahn mutant strains