Serotype-related variations in the virulence level of S. pneumoniae. (A) Survival (left) and bacteremia levels (right) of mice inoculated i.p. with 10² CFU of representative HV (D39, TIGR4, and TH870) strains. n = 5–7. (B) Survival (left) and bacteremia levels (right) of mice inoculated i.p. with 10⁸ CFU of unencapsulated R6 and representative LV (G54, ST556, and TH2919) strains. n = 5–7. (C–E) Survival (left) and bacteremia (right) levels of mice were assessed by i.p. infection with 10⁴ CFU of the isogenic capsule variants generated in serotype 6A strain TH197 (C), serotype 14 strain TH2912 (D), and serotype 3 strain TH2891 (E). n = 5–6. All mice were used on a CD1 background. Data were pooled from two independent experiments.