Serotype-specific inhibition of bacterial clearance by free CPSs. (A) Schematic illustration of CPS treatment. (B–D) Blockage of TH87014 clearance and hepatic capture with CPS14. Mice were treated i.v. with PBS or purified type 14 CPS 2 min before infection with TH87014 and used to assess bacterial clearance as in Fig. 3 E, hepatic capture as in Fig. 3 F, and bacterial killing as in Fig. 3 J. n = 3–6. (E) Inhibition of pneumococcal clearance by CPS of LV but not HV serotypes. Mice pretreated with 400 μg of CPSs were infected with homologous serotypes and assessed for bacterial load in the blood at 10 min as in B. n = 3–6. (F) Visualization of inhibitory effect of CPSs on KC capture of serotype-14, -19F, and -23F pneumococci in mice pretreated with 400 μg of CPSs as in Fig. 6 A. n = 2. (G–I) Serotype-specific blocking of pneumococcal clearance in mice pretreated with one of selected LV CPSs (400 μg/mouse) and infected with serotype-14 (G), -19F (H), or -23F (I) derivatives of TH870 as in B. n = 3–6. (J) Impact of C3 deficiency on the clearance of serotype-14, -19F, or -23F pneumococci. Pneumococcal clearance in WT and C3−/− mice were evaluated as in B. n = 5–6. (K) Impact of CRIg deficiency on the clearance of serotype-14, -19F, or -23F pneumococci in CRIg−/− mice. n = 5–6. CD1 (B–E and G–I) or C57BL/6 (F, J, and K) mice were used. The data were representative results (F) or pooled (B–E and G–K) from two independent experiments. Two-way ANOVA with Tukey’s (B, left panel, and G–J) or Sidak’s (E, F, and K) multiple comparisons test, Ordinary one-way ANOVA with Tukey’s multiple comparisons test (B, right panel, and D), * P < 0.05, **, P < 0.01, ***, P < 0.001, ****, P < 0.0001.
