title: Multiple, heart-cross-reactive epitopes of streptococcal M proteins.
abstract: We present evidence that a highly purified pepsin extract of type 5 streptococcal M protein (pep M5) contains at least three epitopes that are cross-reactive with sarcolemmal membrane proteins of human myocardium. The tissue-cross-reactive determinants of pep M5 are also partially shared with pep M6 and pep M19. Three rabbits immunized with a single 300 micrograms dose of pep M5 developed significant levels of heart-cross-reactive antibodies, as determined by indirect immunofluorescence tests. All three sera also contained antibodies that cross-reacted with pep M6 and pep M19. The heart tissue--specific antibodies that were eluted from sarcolemmal membranes opsonized types 5, 6, and 19 streptococci, indicating that they were directed against protective M protein epitopes on the surface of virulent organisms. Immunofluorescence inhibition tests, using purified M proteins as soluble inhibitors of heart-cross-reactive antibodies, revealed the number and M protein serotype distribution of the tissue-cross-reactive epitopes. Immunoblot analyses demonstrated the sarcolemmal membrane proteins containing the various cross-reactive antigenic determinants.
authors.forename: J B
authors.initials: JB
authors.lastname: Dale
authors.forename: E H
authors.initials: EH
authors.lastname: Beachey
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis / Q000096:biosynthesis / Q000502:physiology; D000942:Antigens, Bacterial / Q000276:immunology*; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000276:immunology*; D002352:Carrier Proteins; D003429:Cross Reactions; D000939:Epitopes / Q000276:immunology*; D008565:Membrane Proteins / Q000276:immunology; D009206:Myocardium / Q000276:immunology*; D009895:Opsonin Proteins / Q000502:physiology; D010587:Phagocytosis; D011817:Rabbits; D012508:Sarcolemma / Q000276:immunology; D012703:Serotyping; D013291:Streptococcus / Q000502:physiology
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D000939:Epitopes; D008565:Membrane Proteins; D009895:Opsonin Proteins; C014689:streptococcal M protein