Figure 3
LD50s of mice challenged intranasally with pneumococcal zinc metalloproteinase mutants: (A) Six groups of MF1 outbred mice (n = 12) were infected i.n. with different inocula (105, 106, and 107 CFU) of either TIGR4 wild type strain (open circles) or zmpC mutant (solid circles). (B) Six groups of MF1 outbred mice (n = 6) were inoculated i.n. with 105,106 and 107 CFU of TIGR4 (open circles) or zmpB mutant (solid triangles). (C) Six groups of MF1 outbred mice (n = 6) were infected with different bacterial doses (105, 106, and 107 CFU) of TIGR4 (open circles) or iga mutant (solid diamonds). LD50s are indicated by the dotted line. Differences in survival percentages between the parent strain and IgA protease mutants were statistically analyzed by Fisher's exact test (P < 0.05). LD50 calculation was performed 8 days after observation of survival. Data reported in this figure are taken from the same experiment as those in figure 2.