Cellular interactions of covR/S mutant group A Streptococci.

Group A Streptococci (GAS) are responsible for a wide array of non-invasive and invasive diseases and varying immune sequelae with high rates of mortality and morbidity. GAS strains with a mutation in their covR/S regulatory system are hypervirulent with an increased capacity for causing invasive disease. covR/S mutants augment their virulence through the up-regulation of important virulence factors and target host immune surveillance primarily by inhibiting neutrophils. An in-depth understanding of the immunopathogenesis of covR/S mutants will facilitate the development of vaccine strategies and design. Ultimately, by targeting separate virulence mechanisms, multi-component vaccines may provide improved protective efficacy against hypervirulent GAS infections.