Figure 5. (A andB) Pictures for colonies of MGAS2221 (A) and its MGAS2221ΔsagA-1 (B) under the reversed background. (C) Western blot for detecting the M protein for the stability of the emm-downregulating phenotype of MGAS2221ΔsagA-1. The mutant and MGAS2221 were passed on THY agar plates for 8 times. After the last passage, GAS bacteria were collected from plates and plated on THY agar plate at appropriate dilution, and 3 (lanes 3–5) and 9 (lanes 6–14) colonies were randomly picked from the MGAS2221 and MGAS2221ΔsagA-1 samples, respectively, for western blotting analyses. Lanes 1 and 2 are the starting MGAS2221 and MGAS2221ΔsagA-1, respectively.