FIG. 2.
Mean weight losses in animals 24 h after infection (s.c.) with wild-type (WT) M5 GAS parent strain Manfredo and its isogenic mutant derivatives. A control group inoculated in an identical manner with sterile PBS is also shown. Different groups of mice were inoculated with various 10-fold serial dilutions of strains in PBS; the corresponding groups (dilutions) for each strain are indicated by shading, and the approximate inoculum doses are shown at the top of the diagram. Since precise viable counts for inocula were not available until the day after infection, some variations between strains in the precise infective doses administered at comparative dilutions were unavoidable. However, these variations were small, ranging from 2.4 × 109 CFU to 3.4 × 109 CFU for the highest inoculum doses administered in the experiment depicted here. Error bars indicate standard deviations.