title: Sequence of protective epitopes of streptococcal M proteins shared with cardiac sarcolemmal membranes.
abstract: Synthetic peptide fragments spanning the entire amino acid sequence of pep M5 were used to detect epitopes cross-reactive with heart tissue components other than myosin. Heart-cross-reactive pep M5 antibodies were affinity purified by absorption to and elution from purified sarcolemmal membranes. Only one of the synthetic peptides, SM5(164-197)C, inhibited reactivity of the affinity-purified antibodies with pep M5 by ELISA. SM5(164-197)C linked to KLH evoked both opsonic and heart-cross-reactive antibodies in rabbits. In addition to type 5, the immune sera opsonized M types 6, 18, 19, and 49 streptococci. The antisera reacted strongly with isolated cardiac sarcolemmal membranes by immunofluorescence. In Western blots of cardiac tissue, the anti-SM5(164-197)C reacted with a 40 kDa protein but not with myosin. The reaction was inhibited by pep M5 and SM5(164-197)C but not by any of the other peptides spanning pep M5. The cross-reactive anti-SM5(164-197)C affinity purified on sarcolemmal membranes opsonized types 5, 6, and 19 but not type 24 streptococci. These results indicate that SM5(164-197)C contains heart-cross-reactive, opsonic epitopes that are shared among heterologous serotypes of group A streptococci.
mesh_terms: D000595:Amino Acid Sequence; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000276:immunology*; D002352:Carrier Proteins; D003429:Cross Reactions; D000939:Epitopes; D007163:Immunosorbent Techniques; D008565:Membrane Proteins / Q000276:immunology; D009206:Myocardium / Q000276:immunology*; D009500:Neutralization Tests; D009842:Oligopeptides / Q000138:chemical synthesis / Q000276:immunology; D009895:Opsonin Proteins; D010449:Peptide Mapping; D012508:Sarcolemma / Q000276:immunology*
chemical_list: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D000939:Epitopes; D008565:Membrane Proteins; D009842:Oligopeptides; D009895:Opsonin Proteins; C014689:streptococcal M protein