FIG 1.

Deletion of sda1 gene in MGAS2221. (A) Picture of agarose gel electrophoresis for PCR analysis that confirms the deletion of a 429-bp fragment of the sda1 gene in MGAS2221. (B) Picture of agarose gel electrophoresis for comparing the DNase activity in the culture supernatant of various GAS strains. The DNase activity was assayed using calf thymus DNA as the substrate. Lanes: none, THY control; 1, MGAS2221; 2, MGAS2221 Δsda1 mutant; 3, MGAS2221 Δsda1 Δspd3 Δspd mutant; 4, an SpeB^A− variant recovered from mice with MGAS221 Δsda1 mutant infection; 5, an SpeB^A+ isolate from mice with MGAS2221 Δsda1 mutant infection; and 6, GAS strain SF370. (C) Western blot detecting the M protein produced by MGAS2221 (wt) and the MGAS2221 Δsda1 and MGAS2221 Δsda1 Δspd3 Δspd mutants.