Contemporary M1 strains of Streptococcus pyogenes have acquired a DNase gene that improves the virulence of the bacterium, but its expression is repressed by the CovRS regulatory system. Walker et al. report that the bacteria are under selective pressure to mutate the covRS locus to maintain DNase expression for invasive infection (pages 982–986).
- Claire Turner
- Shiranee Sriskandan
