Group A Streptococcus strains and plasmids used in this study.

<p>Group A Streptococcus strains and plasmids used in this study.</p

MGAS315 inhibits TNF-α production at skin infection sites.

<p>Presented are the levels of TNF-α (A), INF-γ (B), IL-6 (C), and IL-1β (D) at skin infection sites and levels of IL-6 and TNF-α (E) and INF-γ (F) in sera at the indicated time points after subcutaneous inoculation of 2.1 x 10⁸ cfu MGAS315 and 2.7 x 10⁸ cfu MGAS6180. Statistical analyses with the two-tailed Mann-Whitney <i>t</i> test for the cytokine levels between MGAS315 and MGAS6180 infections: ns, not significant; ***, P < 0.001; **, P < 0.01; and *, P < 0.05.</p

Comparison between MGAS315 and MGAS6180 in innate immune evasion.

<p>(A) Levels of neutrophils at skin infection sites in subcutaneous infections with 1.1 x 10⁸ cfu MGAS315 and 1.4 x 10⁸ cfu MGAS6180. (B-F) Data in the cytospin analysis of neutrophils infiltration in air sac infections with 6.6 x 10⁷ MGAS315 and 1.1 x 10⁸ cfu MGAS6180: Mean numbers ± error of viable neutrophils in the air sac lavages at the indicated times after GAS inoculation (B) and representative pictures of cytospin slides (C, no dilution of the lavage sample for cytospin; D-F, 2x dilution of the lavage samples for cytospin) comparing relative amounts of intact neutrophils versus cell debris at 4 h and 12 h in MGAS315 and MGAS6180 infections. *, P < 0.05, and **, P < 0.01, for the difference in neutrophil numbers between MGAS315 and MGAS6180 infections at 8 and 12 h, respectively.</p

Replacement of <i>covS</i>^1370T with <i>covS</i>^wt in MGAS315 reduces skin invasion and virulence and enhances neutrophil recruitment in subcutaneous infection of mice.

<p>(A) Neutrophil levels and skin lesion sizes in MGAS315 and MGAS315<i>covS</i>^wt infections. (B) Survival rates of mice infected with MGAS315 and MGAS315<i>covS</i>^wt. Inoculum: 1.3 x 10⁸ cfu MGAS315 and 1.4 x 10⁸ cfu MGAS315 <i>covS</i>^wt.</p

MGAS315 <i>covS</i>^wt and MGAS315 Δ<i>covS</i> have higher skin invasion than MGAS6180 and MGAS6180 Δ<i>covS</i>, respectively.

<p>(A) Relative levels of <i>hasA</i>, <i>spyCEP</i>, <i>sse</i>, and <i>emm</i> transcripts in MGAS315, MGAS315 Δ<i>covS</i>, MGAS6180, and MGAS6180 Δ<i>covS</i>, MGAS6180/pDCBB-<i>covS</i>^wt, and MGAS6180/pDCBB. All the mRNA levels were normalized first to that of <i>gyrA</i> and then to that of each gene transcript in MGAS315. (B) Lesion sizes in subcutaneous infections of mice at 24 h after inoculation after inoculation with 1.3 x 10⁸ cfu MGAS315 <i>covS</i>^wt, 1.2 x 10⁸ cfu MGAS315 Δ<i>covS</i>, 1.4 x 10⁸ cfu MGAS6180, and 1.3 x 10⁸ cfu MGAS6180 Δ<i>covS</i>. Statistical analysis with the One-way ANOVA Newman-Keuls Multiple Comparison Test in panel B: **, P < 0.01 and ***, P < 0.001.</p