Genome-wide analysis of group A Streptococcus

The human pathogenic bacterium group A Streptococcus (GAS) is a major cause of morbidity and mortality worldwide. The genomes of seven GAS strains commonly causing pharyngitis and invasive disease have been sequenced recently. These genome sequences have yielded extensive new information important for GAS pathogenesis research, and have provided new insight into the extent of strain variation within and between serotypes. Importantly, these studies have revealed that bacteriophages are the primary source of variation in gene content between strains. Genome-wide studies also have provided important new data bearing on the molecular mechanisms underlying changes in GAS epidemic behavior. Expression microarray analyses have identified genes and gene networks used by GAS to respond and survive in various environments, including exposure to human polymorphonuclear leukocytes and whole blood. Taken together, genome-wide study of GAS is an area of intensive research that has greatly enhanced our understanding of this pathogen. Keywords: genome; group A Streptococcus; evolution; prophage; pathogenesis; microarray