EPITOPE ANALYSIS OF STREPTOCOCCAL M3 ANTIGEN‐SPECIFIC MONOCLONAL ANTIBODY

Abstract

ABSTRACT The binding domains of four monoclonal antibodies (mAbs) (4E10, 2C11, 1E10 and 3H9) specific for M3, the major protein surface antigen of Streptococcus pyogenes, were determined by Western blot analysis using truncated M3 polypeptides. The data indicate that epitopes for four mAbs are located within the B repeat block in M3 protein. A sandwich enzyme‐linked immunosorbent assay for detecting of M3 protein was established using these mAbs and polyclonal anti‐M3 antibody. The technique would be beneficial to our understanding of the epidemiology and to better control of streptococcal diseases. PRACTICAL APPLICATIONSSevere invasive diseases such as streptococcal toxic shock‐syndrome and necrotizing fasciitis have been mainly caused by M1 and M3 serotypes. The M types are also associated with acute rheumatic fever (ARF). Importantly, serotype M3 strains cause a higher rate of lethal infections than other group A streptococcus (GAS) M types. Since epitopes for four monoclonal antibodies (mAbs) are located within the B repeat block in M3 protein, assays for detecting of the epitopes using the mAbs could be helpful for the detection of severe invasive diseases or ARF.