Evidence for the role of SsE in evasion of bactericidal neutrophil responses.

<p>(A) Deletion of <i>sse</i> enhances neutrophil recruitment. BALB/c mice were subcutaneously inoculated on the back with 1.0×10⁸ cfu MGAS5005 or 1.1×10⁸ Δ<i>sse</i>^MGAS5005. Neutrophil numbers at 24 h post-inoculation were determined by the myeloperoxidase assay. *** (One-way ANOVA analysis): The data is significant for Δ<i>sse</i> site versus buffer control (PBS), MGAS5005 inoculation site (5005inj), MGAS5005 spread area (5005sp), and reverse-complement strain of Δ<i>sse</i> (Δ<i>sse</i>-<i>sse</i>). (B) Significant reduction in neutrophil ingress to Δ<i>sse</i> site, but not to MGAS5005 site, in PAFR^−/− mice compared with BALB/c control mice. Five PAFR^−/− (KO) or BALB/c (wt control) mice per group were subcutaneously inoculated with 0.2 ml PBS, MGAS5005, or Δ<i>sse</i>^MGAS5005 suspension at OD₆₀₀ of 0.8. The statistic analysis data (***, significant; ns, not significant) were obtained from one-way ANOVA analysis of the combined data of two experiments. (C) Efficient clearance of Δ<i>sse</i>^MGAS5005. Numbers of viable GAS at sites of MGAS5005 and Δ<i>sse</i>^MGAS5005 infection at 1, 24, and 48 h after inoculation are shown. Six mice were used for each time point and each strain. Inoculum: MGAS5005, 1.1×10⁸ cfu; Δ<i>sse</i>, 1.2×10⁸ cfu; Δ<i>sse-sse</i>, 1.0×10⁸ cfu.