Figure 2
Virulence of pneumococcal zinc metalloproteinase mutants at different doses of intranasal challenge: Mice were infected intranasally (i.n.) with different doses: panel (A) 107 CFU/mouse, panel (B) 106 CFU/mouse, and panel (C) 105 CFU/mouse. Bacterial strains were TIGR4 (open circles, n = 12 for 106 CFU and n = 6 for 107 and 105 CFU), ΔzmpC (solid triangles, n = 12 for 106 CFU and n = 6 for 107 and 105 CFU), ΔzmpB (open diamonds, n = 6) and Δiga (crosses, n = 6) mutants. Animals were observed for 8 days. Results are expressed as percentage of mice surviving intranasal challenge and subsequent sepsis over time. Statistical analysis (Mann-Whitney-Wilcoxon U Test) was performed considering the time point when mice died (P < 0.01). For statistical purposes, animals still alive after 8 days were assigned a time to death of 192 h. The data referring to the 106 CFU inoculum of the ΔzmpC mutant were already reported in reference [5] combined to bacteremia levels.