GAS is further subdivided into strains by variations in a protein on the surface of the bacterial cell. The M-protein is a major virulence factor for GAS and 80 variations of this protein have been identified to date, through sequencing of the emm gene. (9) M-subtypes of GAS are associated with specific diseases; for example, M1 and M3 are linked with toxic shock syndrome. However, the predominant M-types responsible for ARF in North America and Europe are not the same as those isolated in Africa and the Pacific, which has affected vaccine development for GAS. (