Fig 4. Selection of CovRS mutants of emm12 GAS in subcutaneous mouse infection.

(A) The capacity of SpeB^A+ emm3, emm12, and emm28 invasive isolates to give rise to SpeB^A- variants in mice. Shown are SpeB^A−% among GAS bacteria recovered from skin infection sites of mice at day 4 after subcutaneous inoculation with ~10⁸ cfu of each of the indicated 6 emm3, 3 emm12, and 4 emm28 invasive isolates. (B) Levels of SsE platelet-activating factor acetylhydrolase activity in culture supernatant at the exponential growth phase of 6 SpeB^A- variants and their 2 emm12 SpeB^A+ parent strains listed in Table 4.