Net replication of APEC strains in LB broth, immune and non-immune turkey sera. Viable counts of χ 7122nalR(A) and its isogenic Δrfb mutant (B) were obtained over a 3 h incubation in immune, heat-inactivated immune, non-immune, heat-inactivated non-immune and LB broth. Bacterial counts were determined by sampling 20 μL of culture and performing serial 10-fold dilutions before plating on Mac + Nal agar. The data represent the mean log10 CFU ± standard error from three independent assays performed in triplicate.* = P ≤ 0.05.