Capsule type–dependent evasion of hepatic clearance of invasive E. coli. (A and B) Survival (A) and bacteremia (B) levels of mice infected i.p. with 107 CFU of representative HV (red line) and LV (green line) invasive E. coli isolates. Capsular type of each strain is denoted with superscript characters. n = 5. (C) Schematic illustration of the experimental procedures for genetic switching of the cps genes in E. coli. The original cps locus of the host strain was deleted by Cas9-mediated genome editing with the cps gene-targeting guide RNA, followed by DNA repair through homologous recombination with the 1.5 kb up- and downstream arms of the cps locus. The recipient cps genes were introduced into the cps-negative host mutant through another cycle of Cas9-mediated genome editing and repair. See Materials and methods for more details. (D and E) Bacteremia kinetics (D) and proportional distribution (E) of isogenic E. coli strains in SPX mice during the first 30 min after infection. n = 3. (F) Clearance rates of LV E. coli strains in the presence of free homologous CPSs (400 μg) before i.v. infection with 107 CFU. n = 3–5. (G) Bacteremia kinetics of HV K1 (left) and K5 (right) E. coli in the presence of corresponding CPSs during the first 30 min after infection. n = 3. (H) Clearance rates of LV K2ab E. coli in mice pretreated with each type of free CPSs (400 μg) before i.v. infection with 107 CFU. n = 3–5. (I and J) Bacteremia kinetics of LV isogenic E. coli in C3−/− (I) and CRIg−/− (J) mice during the first 30 min after infection. n = 3. All mice were used in C57BL/6 background. Data were from one experiment (D, E, G, I, and J) or pooled (A, B, F, and H) from two independent experiments. Two-way ANOVA with Sidak’s (F) or Tukey’s (I and J) multiple comparisons test, Ordinary one-way ANOVA with Tukey’s multiple comparisons test (H), ****, P < 0.0001.
