Restoration of Mga Function to a Streptococcus pyogenes Strain (M Type 50) That Is Virulent in Mice

The Mga protein in B514Sm, a Streptococcus pyogenes strain isolated as a mouse pathogen, contains amino acid substitutions at conserved sites that render the protein defective. Replacement of mga50 with the functional homolog mga4.1 restored full expression of Mga-regulated proteins. Restoration of Mga function did not affect fibrinogen binding, nor did it affect virulence in several mouse models of group A streptococcus infection.