Protective and nonprotective epitopes of chemically synthesized peptides of the NH2-terminal region of type 6 streptococcal M protein.

The paper refers to amino acid positions of the mature protein as opposed to the precursor. Antisera were tested for their ability to opsonize type 6 streptococci either by incubation of bacteria with blood containing macrophages in the presence of antisera, after which the percentage of phagocytosis was determined microscopically, or by similar incubation with limited quantities of bacteria, followed by colony counts of residual live bacteria. All three antisera were positive for opsinophagocytosis and were indirectly bacteriocidal.