Phenotypic Variation in the Group A Due to Natural Mutation of the Accessory Protein-Encoding Gene .

Populations of a bacterial pathogen, whether recovered from a single patient or from a worldwide study, are often a heterogeneous mix of genetically and phenotypically divergent strains. Such heterogeneity is of value in changing environments and arises via mechanisms such as gene gain or gene mutation. Here, we identify an isolate of serotype M12 group A (GAS) () that has a natural mutation in , which encodes an accessory protein to the virulence-regulating two-component system CovR/CovS (CovR/S).