MGA and skin infection: Isolates with restored M protein production were recovered at skin infection sites in mice with the c.1571C[7] mga variant, and the majority of these M+ revertants restored the c1571C[8] tract of mga. In addition, some M+ revertants lost another C, leading to a c.1571C[6] mga variant that codes for a Mga with additional 13 amino acid residues at the C-terminus compared with the wt Mga.