Assay of type-specific M antigens on whole group A streptococci
A novel radioimmunoassay of type-specific M antigens on whole group A streptococcal cells is described. Absorbed rabbit anti-M antisera directed against M types 12 and 49 were used for determining M antigens on intact bacterial organisms. Staphylococcal protein A labelled with 125I was used as an anti-antibody reagent. The absorbed antisera were tested against ten homologous and 48 heterologous se