Trivalent M-related protein as a component of next generation group A streptococcal vaccines.

Purpose: There is a need to broaden protective coverage of M protein-based vaccines against group A streptococci (GAS) because coverage of the current 30-valent M protein vaccine does not extend to all types. An additional GAS antigen and virulence factor that could potentially extend vaccine coverage is M-related protein (Mrp). Previous work indicated that there are three structurally related families of Mrp (MrpI, MrpII, and MrpIII) and peptides of all three elicited bactericidal antibodies against multiple types.