Immunization with the PP6 synthetic peptide partially protects mice from invasive GAS strains infection.

<p>The survival rates of the PP4 or PP6 synthetic peptide-immunized mice after infection with the clinically invasive A1 (A) or A20 GAS strains (B). Groups of 5 to 9 BALB/c mice were immunized with the control peptide (n = 5), synthetic peptide PP4 (n = 5) or synthetic peptide PP6 (n = 9) and inoculated via the air pouch route with 2× 10⁸ CFU of the A1 or A20 GAS strains. The survival curves were compared for significance using the log-rank test for the PP6-immunized mice versus the control group (<i>P</i>< 0.01). (C) The area of the skin lesions around the air pouch of the control (n = 5) or PP6-immunized mice (n = 9) at 48 h after A1 or A20 GAS strain infection. *<i>P</i>< 0.05, **<i>P</i>< 0.01, compared with the values determined for PP6-immunized groups.