Protective and nonprotective epitopes from amino termini of M proteins from Australian aboriginal isolates and reference strains of group A streptococci.

Cysteine residue is added to the C-terminal of peptide for conjugation to tetanus toxoid. Cross-reactive peptides 20321-19, 20341-19, Y504S1-20 and 88/301-20 inhibitated opsonization activity of the epitope-specific antisera against the homologous isolate.