FIG. 2.

Competitive index analysis during primary infection (A and B) or secondary infection (C and D) in the spleen (A and C) or liver (B and D). Groups of four or five naive or immunized BALB/c mice were infected with a 1:1 mixture of the reference strain (DP-L3903) and ΔActA3, ΔActA3-GG, or ΔActA6. All mice were sacrificed 60 h postinoculation. Average fold defect was calculated by dividing the number of reference strain CFU by the number of test strain CFU for each organ. Primary infection competitive indexes of ΔActA6 and ΔActA3-GG were significantly lower in livers than spleens, with two-sided P values of 0.0004 for ΔActA6 and 0.0002 for ΔActA3-GG by the Mann-Whitney test as calculated by MiniTab (State College, Pa.) software. Liver competitive indexes of ΔActA6 and ΔActA3-GG were significantly lower during secondary infection than during primary infection, with two-sided P values of 0.037 for ΔActA6 and 0.0048 for ΔActA3-GG. Symbols: ○, outlying value as determined by KaleidaGraph (Synergy Software, Reading, Pa.); ∗, underestimated values (1 or 0 erythromycin-sensitive colonies out of approximately 200 screened). y axis, competitive index.